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CONTENTS

Dave’s Universe The inside

scoop from the editor.

Sky This Week

A daily digest of celestial

events.

News The latest

updates from the science

and the hobby.

Ask Astro Archives

Answers to all your cosmic questions.

4 ASTRONOMY • DECEMBER 2018

18 COVER STORYMission Moon 3-DExplore the lunar surface as the

Apollo astronauts did, in vivid

stereoscopic detail.

DAVID J. EICHER AND BRIAN MAY

28The historic flight of Apollo 8 As we celebrate the golden

anniversary of humanity’s irst

trip to the Moon, command

module pilot Jim Lovell recounts

the epic voyage. RICHARD TALCOTT

36Sky This MonthVenus shines brilliantly.

MARTIN RATCLIFFE AND

ALISTER LING

38StarDome and Path of the PlanetsRICHARD TALCOTT;

ILLUSTRATIONS BY ROEN KELLY

44Explore nearby deep-sky gems Interested in observing a red

dwarf, supernova remnant, or

galaxy cluster? We’ve got you

covered. ALAN GOLDSTEIN

48Observe shadow play on the Moon he efects of light and dark on

the lunar terminator ofer some

great observing fun.

PHIL HARRINGTON

52Meet an expert in remote astroimaging Mark Hanson admits he was

never a stellar student, but his

photography is out of this world.

58Astronomy tests Meade’s new astrograph his great-looking scope will help

you create even better-looking

images. JONATHAN TALBOT

68Ask AstroSupernova signals.

COLUMNSStrange Universe 12BOB BERMAN

Secret Sky 62STEPHEN JAMES O’MEARA

Observing Basics 64GLENN CHAPLE

Binocular Universe 66PHIL HARRINGTON

QUANTUM GRAVITYSnapshot 9

Astro News 10

IN EVERY ISSUEFrom the Editor 6

Astro Letters 8

New Products 60

Advertiser Index 65

Reader Gallery 70

Breakthrough 74

FEATURES

DECEMBER 2018VOL. 46, NO. 12

28

Astronomy (ISSN 0091-6358, USPS 531-350) is published monthly by Kalmbach Media Co., 21027 Crossroads Circle, P. O. Box 1612, Waukesha, WI 53187–1612. Periodicals postage paid at Waukesha, WI, and additional offices. POSTMASTER: Send address changes to Astronomy, P.O. Box 62320, Tampa, Fla. 33662-2320. Canada Publication Mail Agreement #40010760.

ONLINE FAVORITES

Go to www.Astronomy.com for info on the biggest news and

observing events, stunning photos, informative videos, and more.

ON THE COVER During Apollo 12, astronaut Alan Bean descends the Lunar Module ladder, imaged by Pete Conrad. NASA

Online Content Code: ASY1812Enter this code at: www.astronomy.com/code

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Published by

New from Heather Couper & Nigel Henbest

The Universe ExplainedA Cosmic Q&A

In their illustrious work in astronomy, Couper and Henbest collected hundreds of the most popular astronomy questions people have asked. Here are nearly 200, with the answers, all informative.

The topics are fascinating, the answers illuminating, � lled with historic detail, debate, changes to theories and discoveries — and packed with personalities.

14 chapters — from Space Travel to Black Holes, Alien Life to The Big Bang. There’s no question or concept too dif� cult to explain and illustrate for Couper and Henbest. A great read and an excellent gift.288 pages in brilliant color

paperback, $19.95

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With annotations and tips for best viewing

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B Y D A V I D J . E I C H E R

FROM THE EDITOR

W ith this issue,

we begin to

commemorate

one of the

greatest anni-

versaries associated with the

exploration of space.

Fifty years ago, the Apollo

program, which landed

humans on the Moon for

the first time, succeeded

with its first trans-lunar

flight, Apollo 8. That craft,

piloted by Frank Borman,

James Lovell, and Bill

Anders, swung around the

Moon and returned to Earth,

in a dress rehearsal

for the Apollo mis-

sions to come.

Over the coming

months, Astronomy

will celebrate 50th

anniversaries of the Apollo

missions with a variety of

special features and stories.

In this issue, we present

Senior Editor Rich Talcott’s

detailed interview with

Jim Lovell, now 90 years old

and as sharp as ever, center-

ing on the experience of

Apollo 8. Whether you were

alive at the time of Apollo 8

or not, you’ll think this rec-

ollection extremely special,

I’m sure.

That story is coupled with

a feature adapted from my

latest book, Mission Moon

3-D, written with Brian May,

astrophysicist and well

known as a founding mem-

ber and the guitarist of

Queen. One of Brian’s pas-

sions is stereo photography,

and he and his team have

produced a variety of stereo

photography books, mostly

focusing on Victorian

England and photography’s

early days.

Mission Moon 3-D is dif-

ferent. Our group has pro-

duced more than 150 stereo

views of the space race and

Apollo missions, most never

before seen in stereo. You can

view the images with 3D

depth, in this story and in the

book, with Brian’s OWL ste-

reoscope viewer (available at

www.MyScienceShop.com),

or by relaxing your eyes and

“free viewing” the images by

allowing them to merge

together.

The book is out now and

contains a unique perspec-

tive on those heady days 50

and more years ago. We

present numerous historic

images, a story of the space

race from both sides — the

U.S. and Soviet Union —

and new stories of the astro-

nauts and their experiences.

We also present coverage

of some of the manned and

unmanned missions since

the Apollo days, including

the International Space

Station and the New

Horizons probe to Pluto.

And we look at the cul-

tural and musical legacy of

the ’60s and the rapid era of

change, from Vietnam to

Woodstock to the growing

momentum of rock ’n’ roll,

up to the phenomenon of

Live Aid.

We’re running a

special contest for the

chance to win one of

five copies of Mission

Moon 3-D signed

by Brian May and me. Visit

astronomy.com/missionmoon

to enter.

The book contains a fore-

word by Charlie Duke, who

says this experience will give

you the “closest thing to

walking on the Moon with-

out going there,” and an

afterword by Jim Lovell.

You can order the book

here: https://myscienceshop.

com/product/book/81192

Yours truly,

David J. Eicher

Editor

Celebrating Apollo

Editor David J. EicherArt Director LuAnn Williams Belter

EDITORIAL

Senior Editors Michael E. Bakich, Richard TalcottProduction Editor Elisa R. Neckar Associate Editors Alison Klesman, Jake ParksCopy Editor Dave Lee Editorial Assistant Amber Jorgenson

ART

Graphic Designer Kelly KatlapsIllustrator Roen KellyProduction Specialist Jodi Jeranek

CONTRIBUTING EDITORS Bob Berman, Adam Block, Glenn F. Chaple, Jr., Martin George, Tony Hallas, Phil Harrington, Korey Haynes, Jeff Hester, Liz Kruesi, Ray Jayawardhana, Alister Ling, Steve Nadis, Stephen James O’Meara, Tom Polakis, Martin Ratcliffe, Mike D. Reynolds, Sheldon Reynolds, Erika Rix, Raymond Shubinski

SCIENCE GROUP General Manager Tim PaulsonExecutive Editor Becky LangDesign Director Dan Bishop

EDITORIAL ADVISORY BOARD

Buzz Aldrin, Marcia Bartusiak, Timothy Ferris, Alex Filippenko,Adam Frank, John S. Gallagher lll, Daniel W. E. Green, William K. Hartmann, Paul Hodge, Edward Kolb, Stephen P. Maran, Brian May, S. Alan Stern, James Trefil

Kalmbach MediaChief Executive Officer Dan HickeySenior Vice President, Finance Christine MetcalfVice President, Content Stephen C. GeorgeVice President, Consumer Marketing Nicole McGuireVice President, Operations Brian J. SchmidtVice President, Human Resources Sarah A. Horner

Senior Director, Advertising Sales and Events David T. Sherman Advertising Sales Director Scott RedmondCirculation Director Liz RunyonArt and Production Manager Michael SolidayNew Business Manager Cathy DanielsRetention Manager Kathy SteeleSingle Copy Specialist Kim Redmond

ADVERTISING DEPARTMENT

Phone (888) 558-1544Advertising Sales Manager Steve MeniAdvertising Sales Representative Dina Johnston, [email protected] Services Representative Christa Burbank, [email protected]

RETAIL TRADE ORDERS AND INQUIRIES Selling Astronomy magazine or products in your store: Phone (800) 558-1544Outside U.S. and Canada (262) 796-8776, ext. 818Fax (262) 798-6592Email [email protected] www.Retailers.Kalmbach.com

CUSTOMER SALES AND SERVICE Phone (877) 246-4835 Outside U.S. and Canada (813) 910-3616Customer Service [email protected] Digital [email protected] Back Issues [email protected]

CONTACT US Ad Sales [email protected] Astro [email protected] [email protected] [email protected] [email protected] Gallery [email protected] Phone (262) 796-8776

Copyright © 2018 Kalmbach Media Co., all rights reserved. This publication may not be reproduced in any form without permission. Printed in the U.S.A. Allow 6 to 8 weeks for new subscriptions and address changes. Subscription rate: single copy: $5.99; U.S.: 1 year (12 issues) $42.95; 2 years (24 issues) $79.95; 3 years (36 issues) $114.95. Canadian: Add $12.00 postage per year. Canadian price includes GST, payable in U.S. funds. All other international subscriptions: Add $16.00 postage per year, payable in U.S. funds, drawn on a U.S. bank. BN 12271 3209 RT. Not responsible for unsolicited materials.

Follow the Dave’s Universe blog: www.Astronomy.com/davesuniverse

Follow Dave Eicher on Twitter: @deicherstar

TO WIN a copy of Mission Moon 3-D, visit

astronomy.com/missionmoon

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ASTROLETTERS


Image vs. impressionIn your Snapshot article, “The first

interstellar asteroid,” in the April issue,

you commit the cardinal sin of not label-

ing an artist’s drawing as such. Neither

the caption nor the story indicates that

the picture of ‘Oumuamua is an artist’s

impression, not a real image. I’m sure you,

too, have been annoyed at mainstream,

non-scientific news sources implying that

we’ve captured actual images of objects,

like Earth-like exoplanets. Please assure

me that this was a one-time oversight.

— Ray Gedaly, The Woodlands, TX

The concept that a speed greater than the

escape velocity is needed is only valid in a

one-shot deal, after which your rocket

then coasts on its own.”

So, you are exactly right: Escape veloc-

ity is the speed needed to achieve, in one

shot, escape from the surface of a body.

Rockets keep firing over time, so they can

move slower than the escape velocity and

still break free of gravity’s pull, given

enough time. Because rockets are so famil-

iar a concept and the option we currently

use to achieve spaceflight, they seemed the

natural example in this case. Next time,

we’ll try to illustrate this concept in a way

that leaves less opportunity for confusion.

— Alison Klesman, Associate Editor

An undeniable talentPraise should be given to illustrator Roen

Kelly for organizing so much information

in an understandable and eye appealing

way. The rocket summary on page 20 of

the August issue is a work of art.

— James McLeod, Charlotte, NC

Escape velocity and accelerationI was reading an article on page 13 of

the July 2018 issue of Astronomy that’s

titled “How fast must a rocket travel to

leave each planet?” but that’s not the

same as escape velocity, which is what

the speedometer shows. A rocket doesn’t

have to travel 7 miles a second to leave

Earth because it has constant accelera-

tion to counteract the effects of gravity.

Escape velocity is the speed to leave the

atmosphere if there’s no added energy.

The title is a bit misleading since rockets

have perpetual thrust. — Alexander Zaleski,

Greenwich, CT

Astronomy respondsYour letter harks back to a statement

made by Bob Berman in his January 2018

column, “Earth’s gravity: A downer?” In

it, he writes about a debate he had with

the astrophysics chair at Columbia

University over this very point. He clari-

fies the issue succinctly by stating,

“Escape velocity simply doesn’t apply if

you’re supplying further energy to the job.

ESO

/M. K

OR

NM

ESSE

R

We welcome your comments at Astronomy Letters, P. O. Box 1612, Waukesha, WI 53187; or email to [email protected]. Please include your name, city, state, and country. Letters may be edited for space and clarity.

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W W W.ASTRONOMY.COM 9

SNAPSHOT

Rubble pileHayabusa2 arrives at Ryugu.

The Japanese Aerospace

Exploration Agency’s

Hayabusa2 spacecraft arrived

at the near-Earth asteroid

Ryugu on June 27. The craft

set off on its 3.26 billion-

mile (5.24 billion kilome-

ters) round-trip journey in

late 2014. When Hayabusa2

arrived, mission scientists used

images like this one, taken

July 20 from a distance of just

under 4 miles (6 km), to scope

out a landing site for the space-

craft’s Mobile Asteroid Surface

Scout (MASCOT).

The probe will use an array

of instruments, including the

MASCOT lander and three

small rovers, to dissect the

diamond-shaped asteroid’s

composition, study its physical

properties, and, most excit-

ingly, shoot a projectile into

the asteroid’s surface to eject

pieces small enough to bring

back to Earth. Since asteroids

have remained more or less

unchanged since their cre-

ation, their compositions allow

astronomers to determine the

time, place and conditions in

which they formed, revealing

the specific molecules that

were present in our infant solar

system. — Amber Jorgensen JAX

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LAST GASP

Astronomers found a strange double-shelled planetary nebula they believe was created by a shock wave generated late in the star’s life.

NO-GO

A NASA-sponsored study found that terraforming Mars to create an Earth-like environment for humans is not possible with current technology.

CREW SELECTION

NASA has introduced the U.S. astronauts who will crew the first flights of two commercial spacecraft, Boeing’s CST-100 Starliner and SpaceX’s Crew Dragon.

ASTRONEWS

Io

0Europa

41Ganymede

131Callisto

141


MINORITY RULES. Although protons make up only 5 percent of a neutron star, the particles are disproportionately active when they interact with the more numerous neutrons, likely determining several of the star’s key properties.

W hile the Sun might seem an easy

target for astronomers, it still har-

bors numerous mysteries. One is

the nature of its corona — the

thin, outermost layer of the Sun’s atmo-

sphere, visible from Earth only during a total

solar eclipse. Stretching millions of miles

and reaching temperatures above 2 million

degrees Fahrenheit (1 million degrees

Celsius), the corona is perplexingly 300

times hotter than the Sun’s so-called surface,

1,000 miles (1,600 kilometers) below.

Launched August 12 from Cape

Canaveral, Florida, NASA’s Parker Solar

Probe will become the first spacecraft to fly

through the blistering gas, returning mea-

surements from within this poorly under-

stood region of our star’s atmosphere. The

probe will loop the Sun more than 20 times

in seven years, approaching as close as

3.9 million miles (6.2 million km) — seven

times closer than previous spacecraft, and

about one-tenth Mercury’s distance from

the Sun.

TWO MAJOR MYSTERIESThe mechanism behind the corona’s

extreme temperatures is unknown. Leading

theories propose that either electromag-

netic waves or bomblike “nanoflares,”

smaller versions of solar flares, could be

responsible. To find a definitive answer,

astronomers need measurements that other

probes can’t record.

“All of our work over the years has

culminated to this point: We realized we

can never fully solve the coronal heating

problem until we send a probe to make

measurements in the corona itself,” said

Parker Solar Probe deputy project scientist

Nour Raouafi of the Johns Hopkins

University Applied Physics Laboratory, in a

press release.

The corona is also responsible for the

solar wind, an outflow of charged particles

accelerated by the extreme temperatures to

speeds of around 1 million mph (1.6 million

kilometers per hour). The solar wind causes,

among other effects, aurorae. Because

astronomers don’t understand what’s heat-

ing the corona, they also don’t understand

entirely how the solar wind is generated.

Solar wind disturbances can affect Earth in

many ways, from increased auroral activity

NASA PROBE WILL TOUCH THE SUN

to electrical blackouts and disruptions in

satellite function and communications.

“The Parker Solar Probe will help us do

a much better job of predicting when a dis-

turbance in the solar wind could hit Earth,”

said Justin Kasper, a professor of climate

and space sciences and engineering at the

University of Michigan.

A LONG TIME COMINGThe idea for a probe that would touch the

Sun was proposed 60 years ago, making the

Parker Solar Probe NASA’s oldest success-

fully launched mission proposal. Originally

called Solar Probe Plus, the spacecraft was

renamed in 2017 for solar astrophysicist

Eugene Parker. It is the first time the agency

has named a mission after a living person.

The car-sized probe carries four instru-

ment suites protected by a nearly 8-foot

(2.4 meters) heat shield of 4.5-inch-thick

(11 centimeters) foam and carbon compos-

ite. The shield will reach temperatures of

2,500 F (1,370 C) on its Sun-facing side,

but the instruments behind it will remain

a comfortable 85 F (30 C).

“For scientists like myself, the reward of

the long, hard work will be the unique set of

measurements returned by Parker,” said

Adam Szabo, the probe’s mission scientist at

NASA’s Goddard Space Flight Center. “The

solar corona is one of the last places in the

solar system where no spacecraft has visited

before. It gives me the sense of excitement

of an explorer.” — Alison Klesman

The Parker Solar Probe will solve some of our star’s biggest mysteries.

BEAT THE HEAT. The Parker Solar Probe’s disk-shaped heat shield will protect the probe’s instruments from the searing heat as it flies through the corona to collect data on this mysterious portion of the Sun’s atmosphere.

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HOW MANY CRATERS ON JUPITER’S MOONS?

METEORITE MARKS. The Italian astronomer Galileo Galilei discovered the four largest moons of Jupiter in 1610. As telescopes improved, we began to see features on those moons, although we couldn’t spot them clearly. Then, in 1979, the two Voyager spacecraft flew by the jovian system, and we began to map their surfaces. Subsequent spacecraft have added to the picture. — Michael E. Bakich

FAST FACT

Io has no sizable craters because its volcanoes continually

restructure the moon’s surface.

AST

RO

NO

MY

: RO

EN K

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ASTRONEWS


A supernova fades away

Sagittarius A*, the supermassive black hole that dwells in the center of the Milky Way, is about 4 million times the mass of our Sun. Astronomers have long kept their eyes on a mys-terious group of high-speed stars that circle it. On May 19, one of those stars, called S2, passed through the black hole’s gravitational field.

The event was recorded in incredi-ble detail, and it gave scientists a prime opportunity to study whether a phenomenon predicted by Einstein’s theory of general relativity, dubbed gravitational redshift, takes place under the most extreme cases. And, it turns out, it does.

Gravitational redshift happens as light travels through an intense gravi-tational field and loses some of its energy, causing it to shift toward the red, or less energetic, end of the elec-tromagnetic spectrum. As the light increasingly feels the pull of gravity, it must work harder to keep traveling at a constant speed. So rather than oscillating at its original frequency, its wavelength is stretched out, becoming longer.

Scientists have long hoped to observe how this phenomenon plays out within the realm of a black hole, but Sagittarius A* lies some 26,000 light-years away, hidden behind large clouds of dust and gas. Recently, however, the European Southern Observatory (ESO) equipped the Very Large Telescope array (VLT) with a new tool called GRAVITY. It combines

light harvested by VLT’s four tele-scopes, yielding 15 times the resolv-ing power and accuracy as just one of the telescopes. Such resolution is equivalent to being able to observe a tennis ball on the Moon from Earth.

This setup let astronomers gather hour-by-hour measurements as S2 passed by Sagittarius A*. They watched what happened as the star came within 12 billion miles (19 bil-lion kilometers) of the black hole. During this close encounter, S2 reached speeds of nearly 5,000 miles (8,000 km) per second, nearly 3 per-cent the speed of light.

The ESO team compared the new data with previously collected data of S2’s last such approach 16 years ago, to understand how the star’s dipping into the intense gravitational field altered its light. They confirmed that light emitted from the star became less energetic — drained of energy, if you will — due to the pull of the black

hole, shifting to a lower frequency.“This is the second time that we

have observed the close passage of S2 around the black hole in our galac-tic center. But this time, because of much-improved instrumentation, we were able to observe the star with unprecedented resolution,” said Reinhard Genzel of the Max Planck Institute for Extraterrestrial Physics, and co-author of a paper on the results published July 26 in Astronomy & Astrophysics, in a state-ment. “We have been preparing intensely for this event over several years, as we wanted to make the most of this unique opportunity to observe general relativistic effects.”

Moving forward, the researchers plan to monitor how this encounter may have shifted S2’s trajectory, which will yield insights into the distribution of gas and dust around Sagittarius A*. — Michelle Hampson, Jake Parks

QUICK TAKES

WATER WORLDSOne-third of known super-

Earths may be up to 50 percent water by mass. For

comparison, Earth is 0.02 percent water by mass.

•NEW SOURCES

Astronomers superimposed multiple images of the sky to

create a new catalog of almost 72,000 X-ray sources.

•SEARCHING SUBURBIA

The outskirts of galaxies are likely prime spots to look for the

black hole collisions that generate gravitational waves,

new research suggests.

•SNAIL’S PACE

A rebounded shock wave from a massive star’s supernova

explosion surprised astronomers when it caused effects lasting hours, instead

of just a few seconds.

•TERRIBLE TWOS

Meteorite crystals older than Earth show the infant Sun

bombarded the solar system with loads of energetic

particles, as is seen in other young stars.

•ALF

An international team of astronomers identified for the

first time one source of a radioactive molecule in space: 26-aluminum fluoride (26AlF),

found in the variable star CK Vulpeculae.

•VERY COOL

A space station experiment produced ultra-cold atoms,

known as Bose-Einstein condensates, with

temperatures just one ten-millionth of a kelvin

above absolute zero.

•SIT TIGHT

For the second time this year, India has delayed its next lunar spacecraft mission,

Chandrayaan-2. The new launch window begins in January 2019.

•FAR OUT

The new record-holder for most distant radio galaxy ever

discovered is TGSS J1530+1049, some 12 billion light-years away.

•HOT STUFF

For the first time, astronomers have detected titanium and iron in the atmosphere of an

alien world that just so happens to be the hottest exoplanet

ever discovered. — J.P.

DISRUPTIVE NEIGHBOR. New research suggests many strange features of the outer solar system, such as the orbits of objects beyond Neptune, are well explained by a close encounter with another star while the Sun was still forming.

Star’s black hole encounter confirms Einstein’s theory

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ZAP AND SNAP. The Very Large Telescope array uses a laser guide star and four connected infrared telescopes to help astronomers pierce the turbulent core of our galaxy and study the supermassive black hole that lurks there. G. HÜDEPOHL/ESO

OLD AND NEW. NASA’s Spitzer Space Telescope captured one of the Milky Way’s oldest and largest supernova remnants, dubbed HBH 3, in this infrared image, which combines data at 3.6 micrometers (blue) and 4.5 micrometers (red). The wispy streams of red at the center are likely molecular gas that became energized when the star exploded and created a shock wave, sometime between 80,000 and 1 million years ago. The remnant lies 6,400 light-years from Earth and is estimated to stretch 150 light-years in diameter. The image also shows a cloudlike white region (left), which represents a portion of neighboring star-forming regions known as W3, W4, and W5. — A.J.

Multiverse theories posit that our universe is one of many, in which countless possible scenarios have played out. PIXABAY


T he perennial desire

to find an answer

to the question,

“What’s going on

here?” is taking

increasingly bizarre turns. One

such turn is the recent buzz

that the cosmos is possibly an

artificial construction.

The concept has become

so widespread that it even

appeared in a movie review in

The New York Times May 10,

in which science columnist

Dennis Overbye wrote, “The

news from some physicists like

the late Stephen Hawking is

that the universe might be a

hologram, an illusion like the

three-dimensional images on a

bank card. Some cosmologists

have argued that it is not incon-

sistent — at least mathemati-

cally — to imagine that the

entire universe as we know it

could just be a computer simu-

lation, as in The Matrix.”

This is certainly an appropri-

ate creation myth for our time!

Could it be true?

It’s not inconceivable that

some aliens could be so far

ahead of us that they could

design such a computer code.

And with artificial intelligence

rapidly advancing even in our

own lifetimes, the classical

question about whether com-

puters could gain sentience, a

sense of themselves, would be

answered if we ourselves were

indeed such computer entities,

programmed to think and have

memories. Certainly, the visible

world all around us could be

replicated by computers —

we’ve all experienced 3D movies

that fully capture a sense of

STRANGEUNIVERSE

We’re now exploring a whole new kind of creation myth.

B Y B O B B E R M A N

Is the universe a hologram?

depth and yet actually occur on

a flat, two-dimensional screen.

Given another century or mil-

lennium of programming prog-

ress, why couldn’t nature be

synthetically replicated?

OK, those of you who are

quick thinkers, I can anticipate

your objection. Namely, if our

human lives and experiences

can be explained as computer

code, this still doesn’t explain

the origin of the alien life forms

that created this artificial digi-

tal realm. That remains an

enormous loose end.

But I have deeper problems

with the idea. I can’t express

them any better than did

physicist Moshe Rozali of the

University of British Columbia

in response to a March 2017

blog post by Scott Aaronson

discussing the simulation

hypothesis. Rozali wrote in a

comment: “My main problem

with the simulation story is not

(only) that it is intellectually

lazy or that it is masquerading

as some deep foundational

issue. As far as metaphysical

speculation goes it is remarkably

unromantic. I mean, your best

attempt at a creation myth

involves someone sitting in

front of a computer running

code? What else do those

omnipotent gods do, eat pizza?

Do their taxes?”

There’s another f law, too. I

think we should automatically

be chary of explanations that

align with our current technol-

ogy, because it smells like

anthropomorphism. We saw

this a few decades ago when

some popular books claimed to

explain Peru’s Nazca Lines as

runways built by ancient aliens

to land their spacecraft. This

should have aroused skepti-

cism simply because runways,

while common nowadays, are a

very transient item in Earth’s

history. Imagining any of our

current tech needs or gadgets

like cellphones or toasters as

alien devices suggests we’re

“projecting.” It would be like

explorers in the 1890s finding

a circle on a cave wall and

believing it’s a drawing of an

ancient alien in a hot-air bal-

loon. Alien gadgets resembling

whatever is humankind’s cur-

rent leading-edge stuff should

automatically be tossed into

the “most unlikely” bin.

Thus these popular holo-

gram and computer-simulation

creation myths seem worse

than unimaginative. They defi-

nitely make my mental alarm

lights flash, even if my brain is

only a simulation.

Have we got any better cos-

mic models for you?

A growing favorite is the

multiverse. But you should

know there are several compet-

ing multiverses. The first was

the quantum theory explana-

tion proposed in 1957 by Hugh

Everett. Called the Relative

State and later renamed the

Many Worlds Interpretation,

the idea was that every time

anything happens, the alterna-

tive outcome also occurs in

some parallel universe.

You were too shy to ask out

the prom queen. But since it

could have happened, it did

happen, and somewhere out

there you and she are married

and living in a parallel Peoria.

For real. Many physicists accept

that a new universe pops into

existence each time you make a

left instead of a right turn.

Why would anyone believe

this? Well, it would explain the

wave-particle duality of light,

which we see in double-slit

experiments. In such experi-

ments, photons must “choose”

whether to act as a particle or a

wave, based on whether you’re

watching them go through the

slit or not. It’s a strange con-

cept. But if the dual nature we

observe is actually due to the

“leakage” of photons from par-

allel universes into ours, inter-

fering with the results by acting

differently than the photons

that belong here, no strange

explanation is needed.

Cosmology has its own sepa-

rate set of multiverses, but

these may be physically sepa-

rated from us, beyond our own

observable universe. They’re

proposed to make the oddly

life-friendly physical constants

of our cosmos seem more plau-

sible, since there should pre-

sumably be countless other

universes that are lifeless.

Need even more universes?

String theory has its own set.

And since each version

allows an unlimited number of

universes, we’re endowed with

multiple infinities. Lucky us.

BROWSE THE “STRANGE UNIVERSE” ARCHIVE AT www.Astronomy.com/Berman.

Join me and Pulse of the Planet’s Jim Metzner in my new podcast,

Astounding Universe, at http://astoundinguniverse.com.

ASTRONEWS

FAST FACT

5°

LEO

HYDRA

CORONA BOREALIS

VIRGO

Denebola Regulus

Alphard

Venus

Earth


Excavation began August 14 on the site of the Giant Magellan Telescope (GMT) at Las Campanas Observatory in Chile’s Atacama Desert. Over the next five months, workers will remove over 140,000 cubic feet (4,000 cubic meters) of rock to prepare the site for the con-crete foundations that will underpin the tele-scope and its support facilities.

Work at the 8,200-foot (2,500 m) Las Campanas Peak is challenging, and crews must excavate 23 feet (7 m) deep before pouring the cement that will serve as the telescope’s pier. Care must be taken to prevent compromising the integrity of the bedrock, which must support the full weight of the telescope’s 1,000-ton (907,000 kilograms) steel structure. The telescope will sit inside a building 22 stories high and almost 185 feet (56 m) wide.

When the GMT is completed, its seven primary mirrors will form a telescope with a diameter of 80 feet (24.5 m). Thus far, five of these segments have been successfully cast. The GMT’s deform-able secondary mirror will counteract the effects of Earth’s atmosphere, offering astronomers the ability to see objects with 10 times the resolution, or sharpness, of the Hubble Space Telescope.

“With the start of construction of the perma-nent buildings on the site, the GMT is showing tangible progress toward completion,” said GMT Organization Project Manager James Fanson in a press release. “In total, we expect to remove 5,000 cubic meters or 13,300 tons of rock from the mountain, and will need 330 dump truck loads to remove it from the summit.”

First light for the GMT is planned for as early as 2024. — A.K.

A bizarre rogue planet without a star is roaming the Milky Way just 20 light-years from the Sun. New research published July 31 in The Astrophysical Journal shows this strange, nomadic world has an incredibly powerful magnetic field some 4 million times stronger than Earth’s, generating spectacular aurorae that would put our northern lights to shame.

The peculiar object — succinctly named SIMP J01365663+0933473 (we’ll call it SIMP for simplicity’s sake) — was first discovered in 2016. At the time, researchers thought SIMP was a brown dwarf: an object too big to be a planet but too small to be a star. However, last year another study showed that SIMP is just small enough, at 12.7 times the mass and 1.2 times the radius of Jupiter, to be con-sidered a planet, albeit a mammoth one.

Gigantic by planetary standards, SIMP also has a mighty magnetic field that produces stunning light shows. However, its aurorae are not generated in the same way as those on our planet. On Earth, the charged particles that cause aurorae primarily come from the Sun in the form of solar wind. But on Jupiter, which also experiences aurorae, the charged particles mainly come from its moon Io. Because SIMP does not have a star bombarding it with particles like Earth does, the researchers believe that SIMP’s aurorae may be produced more like Jupiter’s, which means SIMP likely has a moon.

According to the researchers, the new study, which detected radio emis-sion associated with SIMP’s aurorae, is important because it opens the door for future insights into exoplanetary mag-netic fields and aurorae. Furthermore, the team says this detection method could be used to find other exoplanets without stars, which are notoriously difficult to find. — J.P.

Giant Magellan Telescope excavation begins

Starless planet has a mighty magnetic field

SMALL PACKAGES. Astronomers discovered a black hole almost the same size as the Milky Way’s inside an ultra-compact dwarf galaxy just 300 light-years across. Such a large black hole was not expected within a galaxy of that size.

CONSTRUCTION SITE. The summit of Chile’s Las Campanas Peak, imaged by drone in May 2018, will be the home of the Giant Magellan Telescope. Excavation has begun for the telescope’s pier and support buildings.

SOLITARY SIMP. Shown here in this artist’s concept, SIMP J01365663+0933473 is a massive, starless exoplanet with a powerful aurora-generating magnetic field.

From Mars, Earth would dazzle at magnitude –3.9 and appear about twice

as bright as magnitude –3.2 Venus.

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TWIN WONDERS. As skywatchers continue to enjoy Mars shining brightly in the evening sky, have you ever imagined the view a Martian might have? The stars lie so far away that they wouldn’t look at all different, but the planets are another story. In early December, Earth would appear 44° from the Sun — near its greatest elongation — and would be a beacon in the morning sky among the background stars of Leo. And Venus, just a bit fainter than our planet, would lurk nearby in Virgo. — Richard Talcott

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RED PLANET DELIGHT

ASTRONEWS

Rain

Standing

Lightfromstars

Earth at rest

Running

Earth moving


When charged particles from the Sun slam into Earth’s atmosphere, they impart energy that is subsequently released as light, called an aurora. Although we know much about how aurorae form, this process still holds surprises — such as STEVE, a vibrant violet phenom-enon that captured the attention of the professional scientific community two years ago.

STEVE, which stands for Strong Thermal Emission Velocity Enhancement, originally was dubbed a kind of aurora. Now, a new study published August 20 in Geophysical Research Letters concludes that STEVE is not actually an aurora, after all.

“Right now, we know very little about it,” said Bea Gallardo-Lacourt of the University of Calgary in Canada, and lead author of the paper, in a press release. “And that’s the cool thing, because this has been known by photographers for decades. But for the scientists, it’s completely unknown.”

Gallardo-Lacourt’s team made the discovery using data from the National Oceanic and Atmospheric Administration’s Polar Orbiting Environmental Satellite 17, which passed over an area in eastern Canada dur-ing a STEVE event in 2008. That same event was also captured by a ground-based camera project designed to record auroral activity. By comparing the images with the satellite data, the researchers confirmed that STEVE was present. But the charged particles cascad-ing through Earth’s ionosphere, previously believed to cause STEVE and known to cause the aurora, weren’t. This means STEVE and the aurora were not caused by the same mechanism.

Gallardo-Lacourt’s team is now calling STEVE a kind of “skyglow,” a new type of phenomenon not associ-ated with aurorae. Skyglow is commonly associated with light pollution, but in this case, STEVE’s skyglow is structured and distinct. The team plans to look into whether particle activity associated with STEVE is causing the light directly, or whether the light is gen-erated elsewhere in Earth’s atmosphere.

Whatever the cause, pinning down STEVE’s true nature will ultimately improve our understanding of Earth’s atmosphere and the processes that occur within it. — A.K.

STEVE the aurora isn’t an aurora, after all

Hubble highlights solar system gems

ELUSIVE NATURE. STEVE is a purple, ribbonlike phenomenon that appears during an aurora. New research has uncovered that STEVE is not caused by the same mechanism that generates the northern lights. RYAN SAULT

WHAT IS STELLAR ABERRATION?LEANING LIGHT. Anyone who has attempted to run through a wind-free rainstorm has likely experienced a strange phenomenon known as aberration. This is where the horizontal movement of a running person causes otherwise vertical rain to appear to fall at an angle. The faster a shelter-seeking person is running, the more the rain will appear to fall horizontally. What you may not know is that the movement of Earth through space leads to a similar effect called stellar aberration. The vast majority of telescopes used by astronomers to investigate the cosmos are either on Earth or in orbit around it. Therefore, the entire time these telescopes collect light, they are also moving with respect to the distant stars. This motion causes the starlight to appear to come from a position ahead of the star’s true position. — J.P.

FIRST OF MANY. The newly operational CHIME radio telescope detected its first fast radio burst (FRB) on August 1. CHIME should spot more than a dozen FRBs per day once fully operational.

Generally, stellar aberration causes

a star to appear up to 20" ahead of its

true position.

FAST FACT

10The number of times the crew of Apollo 8 circled the Moon, beginning December 24, 1968. In total, they spent about 20 hours in lunar orbit.

DOUBLE SHOT. NASA’s Hubble Space Telescope was ready for a great photo op — two planetary oppositions — this summer. It snapped this photo of Saturn (left) a few weeks before its late June opposition, and thanks to the planet’s significant tilt toward Earth, Hubble captured Saturn’s famous features in incredible detail. The image shows the planet’s signature hexagon, caused by winds at the north pole, and its prominent rings, which span eight times the radius of the planet. Hubble also imaged Mars (right) just two weeks before opposition, but it was limited by the colossal dust storm engulfing the planet. Despite those circumstances, the telescope still managed to capture Mars’ white polar caps, its Sinus Meridiani feature, and dusty views of two massive impact craters: Schiaparelli Crater along the equator and Hellas basin in the southern hemisphere. — A.J.

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<60 110 160 230 290Location of water ice detections,Moon’s Southern Hemisphere

Location of water ice detections,Moon’s Northern Hemisphere

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Ice discovered on the Moon’s surface

COSMIC RAY GUN. The massive binary stars that make up Eta Carinae produce cosmic rays when their colliding stellar winds accelerate charged particles to nearly the speed of light.

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The Sun’s habitable zone will move outward as it ages, eventually leaving Earth and Mars

to warm Jupiter, Saturn, and Neptune.

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SOLAR SYSTEM COMPARISONSIZE IT UP. A star’s habitable zone is a band around the star in which water on the surface of an orbiting planet could remain liquid. Its size and distance depend on the star’s brightness. In our solar system, only Earth currently resides in the habitable zone. But how does our solar system measure up against others? Are there other planets circling within the habitable zones of distant stars?

The Kepler-186 system, about 500 light-years away, would fit entirely within the orbit of Mercury. Its star is smaller and cooler than the Sun, so its habitable zone is much closer as well. One of its five planets, Kepler-186f, lies within this habitable zone. It orbits every 130 days, receiving one-third the energy that Earth gets from our Sun. The planet is 10 percent larger than Earth, but its mass and composition are not yet known.

The Kepler-452 system 1,400 light-years away has a habitable zone that stretches slightly farther than our Sun’s, owing to its slightly larger, older, and brighter star. Kepler-452b is a super-Earth 60 percent larger than our planet, though its mass and composition are unknown. It orbits inside the star’s habitable zone once every 385 days, at a dis-tance 1.05 times the Earth-Sun separation. —A.K.

COLD AS ICE. A recent review of data from NASA’s Moon Mineralogy Mapper (M3), a visible and infrared spectro-meter that rode aboard India’s Chandrayaan-1 orbiter from 2008 to 2009, shows the first direct evidence of water ice in the cold, dark craters near the Moon’s poles. Scientists discovered the ice by studying scattered sunlight from permanently shaded craters, which produced a weak but detectable signature that matches pure water. This map shows exposed surface ice as orange and blue dots, and indicates the annual maximum temperature of the region. (Darker is colder, brighter is warmer.) The amount of ice on the surface is unknown, but further exploration could help us understand how it got there, as well as its role in the Moon’s formation and evolution. — A.J.

ASTRONEWS


Ultra-hot Jupiters are an odd, hellish class of exoplanets that astronomers are increasingly finding scattered throughout the cosmos. These gas giants sit much closer to their host stars than Mercury does to the Sun, often leading to tidal locking — the same side of the planet always faces the star. Their dayside temperatures can exceed 3,500 degrees Fahrenheit (1,900 degrees Celsius), while nightside temperatures hover around 1,800 F (1,000 C).

In a study accepted for publication in Astronomy and Astrophysics, researchers mod-eled the atmospheres of four known ultra-hot Jupiters that were previously investigated using the Hubble and Spitzer space telescopes. The team concluded that ultra-hot Jupiters are even more two-faced than astronomers initially thought. Specifically, the team found that the dayside temperature of these exoplanets is so intense that the heat can split most types of molecules into their basic building blocks. Since these molecules are broken apart, they remain hidden from the gaze of even our most advanced observatories. This led the research-ers to a surprising conclusion: The dayside atmosphere of an ultra-hot Jupiter more closely resembles a star than a planet.

Although this result is interesting, it also helps explain why astronomers only detect water molecules at the day-night border of ultra-hot Jupiters. The team found that as hydrogen and oxygen atoms make their way to the planet’s cooler nightside, they recombine to form water. But since the nightside is too dark to observe, astronomers can only detect these water molecules right at the border between day and night.

This new research provides a valuable framework that will help astronomers better understand the physical processes that govern these mold-breaking worlds. And with NASA’s planet-hunting TESS telescope already collect-ing data, the more we know, the better. — J.P.

Ultra-hot Jupiters have daysides like stars

MELTING POT. This illustration depicts an ultra-hot Jupiter that sits so close to its host star, its dayside atmosphere is hot enough to boil iron.

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Explore the lunar surface as the Apollo astronauts did, in vivid stereoscopic detail.by David J. Eicher

and Brian May

Astronaut Jim Irwin works at the Lunar Roving Vehicle during the first Apollo 15 moonwalk on July 31, 1971. This view aims northeast, with Mount Hadley in the background, and was taken by mission commander Dave Scott. NASA/JSC

Left: In one of history’s most famous pictures, Buzz Aldrin stands on the lunar surface, gazing at the checklist taped to his wrist. In his helmet visor we see the reflection of Neil Armstrong taking the picture, as well as the Lunar Module Eagle and Buzz’s shadow. Although many have assumed this spectacular photograph was carefully planned to capture an image of two astronauts and the LM, the moonwalkers dismissed it as a lucky shot. Few have ever seen this famous picture in 3D. The image was masterfully converted into 3D by David Burder, and re-edited here just for this project. NASA/JSC


ifty years ago, men traveled a quarter of a million miles through space, and set foot for the first time on our planet’s Moon. Today, this outrageously bold adventure seems as shiny and new as if it were yesterday. It still captures the imagination of kids of all ages — witness the ever-popular LEGO model of a Saturn rocket and the capsules that took men on an epic voyage.

In retelling the story of the space race, its tragedies and triumphs, the Moon landing in July 1969, and the missions that followed, we will take you on a journey in a way never pos-sible before. In our new book, Mission Moon 3-D, we give perspectives on both sides of that scramble to reach the Moon, including stories that could never be told until now. And for the very first time, those stories can also be told through 150 newly created Victorian-style stereo pairs of photographs, viewable in glorious 3D. You can use the OWL stereo viewer that comes with our book, or order one through www.MyScienceShop.com (where the book is also available).

Here is just a sampling of the images and a brief glimpse of the narrative text. On these pages, you will see some “mono”

photographs that need no special apparatus to view. But interspersed among them are the side-by-side pairs of photographs that will give you a uniquely powerful three-dimensional perspective — which Charlie Duke himself has described as making him feel almost as if he were back on the surface of the Moon, as he was in 1972.

The challengeThe whole enterprise began as a rare thing, when John F. Kennedy addressed a joint session of Congress on May 25, 1961. “I believe that this nation should commit itself to achieving the goal,” said the president,

Above: Astronauts acting as commu-nicators monitor the Apollo 13 emergency in Houston’s Mission Control. Seated, left to right, are Deke Slayton, director of flight crew operations; Jack Lousma, capsule communicator; and John Young, backup commander. Standing, left to right, are Ken Mattingly and Vance Brand. NASA/JSC


Apollo 8 on the pad at twilight. NASA/JSC

Left: A view of the damaged Apollo 13 Service Module taken prior to splashdown. This image is essential to understanding what happened: An entire panel was blown off by the oxygen tank explosion, and the interior damage was substantial. In this view, the S-band antenna is visible above the damaged area, and on the right side are the Service Propulsion System engine and nozzle.

NASA/JSC

Above: Commander Pete Conrad descends the ladder of the LM Intrepid, about to become the third man to walk on the Moon, on November 19, 1969, during Apollo 12. He was about to say the legendary words, “Whoopee! Man, that may have been a small one for Neil, but that’s a long one for me!”

NASA/JSC

Left: The Apollo 14 LM Antares reflects a circular flare caused by brilliant sunlight over the Fra Mauro highlands. Alan Shepard and Edgar Mitchell said the unusual ball of light had a jewel-like appearance. At far left is the lower slope of Cone Crater. NASA/JSC


“before this decade is out, of landing a man on the Moon and returning him safely to the Earth.”

This set off a race between the two superpowers, the United States and the Soviet Union, each of whom wanted to demonstrate Cold War superiority. Early in the game, the Soviet program was far ahead of the Americans, with the first satellite (Sputnik 1), the first man into space (Yuri Gagarin), the first spacewalk (Alexei Leonov), and many other firsts. And the Soviet Union had a full-blown expectation of landing explorers on the Moon before the Americans could.

The wheels began to accelerate for what would become the Apollo program, the U.S. attempt to land astronauts on the Moon, even as other preliminary programs took place. Mercury astronauts entered low-Earth orbit, circling the globe. Launch facilities and control centers were built.

Americans graduated to the Gemini program, a two-seated capsule that would allow practice maneu-vers later to be used for the Moon shot. All the while, the Soviet Union raced ahead with their accomplish-ments: the Vostok program, expansion of an enor-mous launch facility in Kazakhstan, and the ambitious Voskhod spacecraft.

Setbacks and successesBoth sides discovered that the exploration of space, the pushing of the envelope, was a dangerous and unpredictable business. Lives were lost in jet aircraft crashes, including that of Gagarin. An explosion at the Soviet Baikonur Cosmodrome killed dozens. The death of the chief Soviet rocket designer, Sergei Korolev, stalled the program, as did fatalities such as the loss of the Soyuz 1 pilot, Vladimir Komorov.

Such tragedies brought the Soviet program almost to a standstill. Meanwhile, the Americans experi-enced disaster when the Apollo 1 spacecraft, in a fully outfitted drill, caught fire, killing its three occupants:

Gus Grissom, Ed White, and Roger Chaffee.

By late 1968, however, NASA and the American program surged ahead, incorporating lessons learned from the Apollo 1 fire. At year’s end, NASA prepared for the first circumlunar test, Apollo 8, with Commander Frank Borman, Command Module Pilot Jim Lovell, and Lunar Module Pilot Bill Anders.

The mission went off successfully, with the crew getting close-up views of the lunar far side, circling our neighbor in space, and returning to Earth for a splashdown two days after Christmas 1968. Not only did the crew see — and photograph — Earth rising over the Moon, but they famously read a biblical creation story on Christmas Eve, sending chills through many of the listeners.

Two more significant tests were left before humans could set foot on the Moon. Apollo 9 would test space-craft components, the pairing of the Command/Service Module and the Lunar Module (LM), and would test engines and docking procedures. That crew consisted of Commander Jim McDivitt, Command Module Pilot Dave Scott, and Lunar Module Pilot Rusty Schweickart. In March 1969, the mission flew without a hitch.

And then came Apollo 10, in which NASA con-ducted a full dress rehearsal, set for May 1969. This mission carried Commander Tom Stafford, Command Module Pilot John Young, and Lunar Module Pilot Gene Cernan. The Apollo 10 crew flew to the Moon, sent the Lunar Module on a descent, and tested everything without actually landing. NASA was now ready for the main event.

Finally, the MoonThe crew of Apollo 11 — Commander Neil Armstrong, Command Module Pilot Michael Collins, and Lunar Module Pilot Buzz Aldrin — blasted off from the Kennedy Space Center on July 16, 1969. The

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Above left: The Apollo 12 LM Intrepid appears to float over the lunar limb as photographed by Dick Gordon inside the Command Module Yankee Clipper on November 19, 1969. The large eroded crater in the foreground is Ptolemaeus, and the second largest is Herschel, on the right. At this time, the LM was 68 miles (110 kilometers) above the Moon’s surface. NASA/JSC


world watched. After a three-day cruise to the Moon, the astronauts prepared for their historic landing.

Armstrong piloted the LM as Aldrin navigated. The two nearly ran out of fuel during their descent, leaving just enough for the return trip. Aldrin called out, “Contact light.” Moments later, Armstrong blurted out, “Houston, Tranquillity Base here. The Eagle has landed.” On the ground, gripped by sus-pense, Charlie Duke, acting as a communicator, replied, “Roger, Twan — Tranquillity, we copy you on the ground. You got a bunch of guys about to turn blue. We’re breathing again. Thanks a lot.”

Some two and a half hours later, Armstrong and Aldrin prepared for the first-ever moonwalk. Armstrong descended the LM’s ladder, stepped onto

the Moon’s powdery surface, and said, “That’s one small step for [a] man, one giant leap for mankind.” He and Aldrin planted a U.S. flag, sampled and collected Moon rocks, and explored the Sea of Tranquillity. Their time the lunar surface lasted 49 minutes. Returning to lunar orbit, and then to Earth, the Apollo 11 crew splashed down in triumph.

Six more missions followed the first Moon land-ing, all of which made for exciting adventures. Apollo 12, with its crew of Pete Conrad, Dick Gordon, and Alan Bean, lifted off near the end of 1969. On the Moon’s surface, Conrad and Bean explored the Ocean of Storms, an area visited earlier by several unmanned missions. This second lunar mission allowed the moonwalkers to explore for nearly eight hours.

Top: This stereo view of the Lunar Roving Vehicle was made by Dave Scott during the third Apollo 15 moonwalk. It appears against the desolate lunar surface at the Hadley Rille landing site, and faces north. The western edge of Mount Hadley is at upper right. NASA/JSC

Astronaut John Young gives the Lunar Roving Vehicle a high-speed workout in the “Grand Prix” run during the third Apollo 16 extravehicular activity. This view is a frame from a motion picture film exposed by a 16mm Maurer camera held by Charlie Duke. NASA/JSC


A temporary setbackBy the spring of 1970, the Apollo program was rolling ahead at full speed. Launch for Apollo 13 was set for April. This mission would set a course for exploring Fra Mauro, a geologically interesting region. The crew of Commander Jim Lovell, Command Module Pilot Jack Swigert, and Lunar Module Pilot Fred Haise launched and set off for the Moon.

Some 56 hours after blastoff, the three conducted a TV interview and then set off on tasks. Swigert stirred the oxygen tank on the Service Module, a routine job that mixed the gases and allowed the gauges to read with precision. Two minutes later, the astronauts heard a “pretty loud bang.” The spacecraft lost oxygen. The crew had to power down the Command/Service Module and use the LM as a “lifeboat,” circling around the Moon without landing, and returning to Earth.

The world watched, hoping a disaster wouldn’t happen. Lovell said the crew were aware they could become “human Popsicles in permanent orbit.” But the Apollo 13 accident was not fatal — the crew, assisted by controllers, returned safely to Earth.

So it would be Apollo 14 that would explore Fra Mauro, the intended site of the previous mission. Alan Shepard, Stuart Roosa, and Edgar Mitchell explored the area in detail, collecting samples, study-ing geology, and accomplishing what Apollo 13 had planned to do.

The final three Apollo missions, which took place in 1971 and 1972, employed one of the most creative devices yet made by humans, the Lunar Roving Vehicle. These most expensive of cars were carried, folded up, on the LM, and utilized by the astronauts on the surface, to extend their range considerably.

In the case of Apollo 15, astronauts Dave Scott, Alfred Worden, and Jim Irwin explored the area of Hadley Rille, a ridge near the edge of Mare Imbrium, and not far from the prominent craters Archimedes, Aristillus, and Autolycus. Equipped with a rover, the range was now so great that exploration and rock collecting became far more powerful. Among the samples they gathered was what they believed to be an old Moon rock they dubbed “Genesis Rock.” The Apollo 15 crew also left a memorial statue to their deceased comrades on the surface, the Fallen Astronaut Memorial.

With its crew of John Young, Ken Mattingly, and Charlie Duke, Apollo 16 conducted serious science on the lunar surface. Exploring the Descartes Highlands,

Above: This view of the Apollo 15 Command/Service Module, taken July 30, 1971, shows the craft in lunar orbit and lets you see the open bay where panoramic and mapping cameras were located in the final three Apollo mission spacecraft. These cameras provided stereo coverage of the lunar surface, whereas prior missions captured stereo images only from the Hasselblad cameras operated by astronauts through the Command or Lunar Module windows. NASA/JSC

Left: Jack Schmitt smiles inside the LM Challenger on December 13, 1972, after the third Apollo 17 moonwalk. He was photographed by Gene Cernan.

NASA/JSC

Above: Gene Cernan salutes the largest U.S. flag deployed during the Apollo missions, on December 12, 1972, at the Taurus-Littrow landing site. Behind him stands the LM Challenger and the lunar rover that traversed the greatest distance of any on the Moon‘s surface, some 22 miles (35 km). This stereo image was taken by Jack Schmitt, the only geologist to walk on the Moon. The long baseline between the two camera positions for these images produces an effect that makes the scene look a bit like a LEGO project! NASA/JSC

Below: Neil Armstrong stands beside the LM. Also visible are the U.S. flag and the solar wind experiment, which was flown on all the Apollo missions. NASA/JSC

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the mission focused on sampling older lunar material that might provide clues to the Moon’s origin.

The end of an eraSimilarly, Apollo 17 focused on an extensive science mission, this time focused on the Taurus-Littrow Valley. Its crew of Gene Cernan, Ron Evans, and Jack Schmitt included the only scientist ever to walk on the Moon (Schmitt). Extensive exploration and collecting netted a great collection of samples, and ultimately the Apollo Moon rocks enabled planetary scientists to understand that the Moon originated in a large impact between Earth and a planetesimal early in the history of the solar system.

On December 19, 1972, the crew of Apollo 17 splashed down. We have not been back to the Moon since, in nearly 50 years. Will humans someday return, and will politicians and the public return to caring more about science, and funding it?

That remains to be seen. In late 1972, the Apollo program had reached the end, and humans had traveled to the Moon, at least for a half century, for the last time.

Mission Moon 3-D: A New Perspective on the Space Race, by David J. Eicher and Brian May, foreword by Charlie Duke, afterword by Jim Lovell, presents the story of the historic lunar landings and the events that led up to them, told in text and 3D images.

Mission Moon 3-D contains new and unique stereoscopic images of the Apollo Moon landings to show what it was like to walk on the lunar surface. The triumph of the Apollo 11 Moon landing takes center stage, with detailed stories and visually stunning images from the six lunar missions that followed. In total, the book includes 150 stereo photos of the Apollo missions and space race, the largest group ever published, and presents photos never seen before in stereo.

The book also delivers a comprehensive tale of the space race. New stories appear from the astronauts, including Lovell’s anecdotes about

the perilous return of Apollo 13. Mission Moon 3-D includes a history of the social and

musical movements of the ’60s and

beyond that trans-formed the world, from Vietnam and

Woodstock to Live Aid. Don’t miss out on

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EXPLORE FROM HOME

Astronomy Editor David J. Eicher is an author of

23 books on science and history. Brian May is an

astronomer, and founding member and guitarist

of the legendary rock band Queen.

This story is adapted from Mission Moon 3-D: A

New Perspective on the Space Race by David J.

Eicher and Brian May, foreword by Charlie Duke,

afterword by Jim Lovell, published October 30, 2018,

by London Stereoscopic Co. and MIT Press, Boston.

Above: Boulders stand in the foreground of this view of the southern rim of Camelot Crater on December 12, 1972. The North Massif lies in the background. The rocks were ejected by the impact that formed Camelot Crater, and their angular shapes and relative lack of dust coating are evidence of the crater’s young age, about 70 million to 80 million years. This stereo view was assembled from images made by Cernan for his panorama at Geology Station 5. NASA/JSC

THE LONDON STEREOSCOPIC CO.

The historic flight of

Earth rises over the lunar limb as Apollo 8 comes out from behind the Moon. The lunar horizon lay about 485 miles (780 km) from the spacecraft when Bill Anders captured the iconic scene. ALL PHOTOS, UNLESS

OTHERWISE STATED: NASA


As we celebrate the golden anniversary of humanity’s first trip to the Moon, command module pilot Jim Lovell recounts the epic voyage. by Richard Talcott

APOLLO 8

Astronomy: Thank you, Captain Lovell, we really appreciate you being here today and talking with us about Apollo 8, whose 50th anniversary is coming up in just a few months. NASA’s original plans were to test the lunar module in Earth orbit on your Apollo mission, but delays in the lunar module program changed those plans. How lucky did you feel that the mission order changed and you were able to go to the Moon instead of testing the lunar module?

Lovell: I guess there’s a certain amount of luck in everybody’s

life, and we were originally going to be Earth orbital. And of course I had been Earth orbital for 14 days in Gemini VII and then Gemini XII. . . . But the change, due to some intelligence we got about the Russians and also due to the fact that Grumman could not get the lunar module ready, actually changed things completely.

I felt elated, to tell you the truth, because [otherwise] I was going to be going around the Earth several times, and so this was entirely new to me. And all admiration to NASA hierarchy that they were able to look at the

spacecraft and take the chances and to make a very successful flight.

Astronomy: Apollo 8 was the first of nine missions that went to the Moon, and there were a lot of things that no one had ever done in history. I’m curious what it felt like to be the first people to fly on the Saturn V and feel the power of that rocket underneath you.

Lovell: We were the first people, and it was the third Saturn V built. The first two were test vehicles, and both of them had problems. So one of the things that NASA

“IT WAS THE BEST OF TIMES, IT WAS THE WORST OF TIMES.” With these dozen words, Charles Dickens launched A Tale of Two Cities. Anyone who looks back to 1968, however, would have to be wearing rose-tinted glasses to see much good. A divisive war, tragic assassinations, and appalling riots rocked the United States. Even 50 years later, it’s hard to find much worth celebrating.

Until the final two weeks of the year rolled around, that is. On the morning of December 21, astronauts Frank Borman, James Lovell, and Bill Anders soared off the launchpad at Florida’s Kennedy Space Center and later that day became the first humans to slip the bonds of Earth’s gravity. Apollo 8 would go to the Moon, orbit our satellite on Christmas Eve, and return safely to Earth on December 27.

This was Lovell’s third trip into space. He had teamed with Borman on Gemini VII in December 1965, when they performed the first rendezvous with another manned spacecraft, and with Buzz Aldrin on Gemini XII in November 1966 in that program’s final mission. Anders was a rookie who would not fly again.

Recently, I had the honor to interview Captain Lovell about the Apollo 8 mission at the Lake Forest Library in Illinois. At 90, he remains as sharp and engaging as he was during the glory days of spaceflight a half-century ago.

“When the engine

stopped and we were up to

a little bit over 23,000 miles an hour, you

look back and see the Earth

shrinking.”

Jim Lovell sat down to chat with Astronomy magazine in June 2018. ASTRONOMY: DAVID J. EICHER


had to think about when they were discussing changing the mission was, “Well, is that Saturn V going to be ready? Is it going to have glitches in it?” And they went to the manufacturers and they talked to them and they said, “Yes, we’re going to be OK, we found out what’s wrong. No problem at all.” . . . In my personal case, I didn’t think too much about it. I took their word for it. We’re going. I didn’t have second thoughts about this flight whatsoever.

As a matter of fact, I was a little bit different than, espe-cially, Frank. Frank looked at it as beating the Russians; I looked at it as a mini Lewis and Clark expedition. We’re going to new territories, we’re going to do new things. You know being first before the Russians was good, but it wasn’t the main reason that I thought it would be pertinent.

Astronomy: Certainly 50 years now in the future the Lewis and Clark aspect is much bigger than the beat-ing the Russians aspect.

Lovell: That’s exactly right.

Astronomy: With all the new experiences, did it help your comfort level to be with Frank Borman on the mission since you had already flown with him on Gemini VII?

Lovell: Yeah, Frank and I knew each other. We spent two weeks in Gemini VII to see how man could live for two weeks in zero gravity. We got to know each other quite well, as you can imagine. And there’s a whole story going by that when we were on the deck of the aircraft carrier, we announced our engagement.

Astronomy: That’s good. Did it feel any different when

The crew of Apollo 8 — (left to right) James Lovell, Bill Anders, and Frank Borman — pose on a simulator at Kennedy Space Center just a month before they took off for the Moon.

“For some reason, I never worried. I took it that this was going to be

a success from the beginning.”


you left Earth’s gravity, being the first people ever to leave Earth’s gravity behind and go toward the Moon? What was that feeling like?

Lovell: Actually, we were so busy doing things, we went around the Earth first of all to test out our spacecraft, that we were concentrat-ing on how the Saturn was working and everything like that. We knew that we were going to the Moon, but it was only at the end of the Earth orbit when everything on the spacecraft was fine, when we lit . . . the third stage of our engine, and it gave us enough velocity and the proper course to coast all the way to the Moon, that I suddenly real-ized, “Hey, we’re leaving the Earth. We’re not just going to Earth orbit.”

And then looking back, right after that, when the engine stopped and we were up to a little bit over 23,000 miles an hour, you could look back and see the Earth shrinking. . . . It was sort of like if you’re in an automobile and you’re going through a tunnel, [when] you look in the rearview mirror and you can see the tunnel opening slowly

closing and closing. That’s exactly what that felt like.

Astronomy: Was it a little scary?

Lovell: No. For some reason, I never worried. I took it that this was going to be a suc-cess from the beginning and I was maybe, blasé? I didn’t tell my wife, Marilyn, “Hey, you know I only have a 50–50 chance of coming back and here are the keys to the car.”

Astronomy: You were the navigator on Apollo 8. Was it easy or difficult to actually sight the stars through the spacecraft window?

Lovell: Much easier than I thought. What I did, my job was to go to Boston, to MIT . . . and they taught me the navigation. Because we had to change the navigation all around. From Earth orbit to going to the Moon was entire-ly different. [It’s] somewhat like shipboard navigation except it is three dimensional, not two, and so I had to learn to use the sextant, and I had to learn to use the computer, and learn the stars, of course, to figure out what they were like.

And when we first got up into space, we sent back our results because most of the initial navigation . . . was done by the ground. They were tracking us, they knew where we are by my work on the computer to keep the gyros from [drift-ing]. And so they would get the information and they were very much pleased, especially MIT, with the results of their system and navigation. And they said, “Oh, Jimmy, you’re doing a good job.” I said, “Well, why not, I was up here last week to practice.”

Astronomy: I gather Frank got sick on the way to the Moon. Did that create any concerns on your part that it might be more than a 24-hour bug kind of thing?

Lovell: No. I knew what it was — he had motion sick-ness. Although he was a strong Air Force captain . . . I was with him for two weeks [on Gemini VII and he got a little queasy]. My biggest regret was not to have called Mission Control and said, “Look it, I know that Frank has only motion sickness. He’s going to join us in a lit-tle while. We are not turning back. Let there be no thought about stopping this mission now. Apollo 8 is going to go to the Moon, we’re going to do those things assigned to us, and we’re going to go with your help.” But I didn’t do that. I just let it float back and forth.

And the doctors were thinking about the return trip. Quite frankly, both my flights, 8 and 13, we had never really practiced the return flight. . . . I think I tried it once or twice on the com-puter. . . . I much rather would have gone right around the Moon and come home.

The three Apollo 8 astronauts walk through a hallway on their way to the launchpad.

Above: The Saturn V rocket that would send Apollo 8 on its way to the Moon makes the slow journey from the Vehicle Assembly Building to Launch Pad 39A.

Left: Seagulls scatter as Apollo 8 lifts into the skies above Florida’s east coast December 21, 1968.


Astronomy: That brings up another question. You mentioned your training in terms of coming back from the Moon, but did your Apollo 8 training really prepare you for the kinds of things that you did on the trip and for all the things you would see? Did you feel comfortably trained ahead of time, or was it surprising in any way?

Lovell: In the short time we had to retrain from an Earth-orbital flight, which was the original Apollo 8 [plan], everything worked. We weren’t surprised. We weren’t surprised when we got to the Moon, either. Of course, we had pictures of the farside before we got there. And so everything worked fine. And it’s amazing. I think the spacecraft, Apollo 8, was one of the few incident-free craft that ever went to the Moon, with the least amount of problems.

Astronomy: Let’s talk a little bit about your reading from the book of Genesis on Christmas Eve. How did it come about, and was it a joint decision among the three of you or was it one in particular?

Lovell: This all started when we started training [and] found out we were going to be orbiting the Moon on Christmas Eve. You know, what a coincidence. First flight to the Moon on a year that, looking back on it now, was a very poor year in the United States — the war was going on, the riots, and the assassinations.

And we said, “Well, can we change the words to ‘The Night Before Christmas’?” That didn’t sound good at all. And “Jingle Bells” was even worse. And finally, I think it was Frank [who knew a PR guy in NASA], and Frank asked him what we could say. And he didn’t quite know . . . but he had a newspaper friend . . . in Washington, D.C. He called and said, “Look it, these fellows want to say something, and we want them to say something, too, when they’re around the Moon on Christmas Eve, but we don’t know what to say. You’re a newspaperman, you’re used to writing all kinds of things like this, could you come up with some good verbiage?”

So one night he [started to think about what we could say], and nothing came out. Until his wife walked down the stairs and asked him,

“Well, what are you doing? You’re up late.” And he told her the story. And she said, “Well, that’s simple — just have them read the first 10 verses of Genesis from the Old Testament. That tells everything.” And so that’s how it came to pass.

Astronomy: You and your crew were the first people ever to see Earth rising as you were coming back from around the farside of the Moon. Could you describe how you took the photo or how the photo was taken?

Lovell: For a long time it was, “Who took that pic-ture?” But actually, the true story is that Bill Anders took the picture. We were coming around, actually it was the third orbit. Bill and Frank were looking out the right window, and we saw the Earth come up. And then the spacecraft [moved] as we were going around the Moon. And I was on the left window, and then I saw the perfect composition that you now see in the famous photograph.

So I said, “Bill, Bill, look here, take this picture.” And I gave him the color film and he said, “Now just a minute Lovell, just a minute.” And then I actually claim that I told him how to compose the picture so it would come out good. But he took the picture. And very fortunately we did that. I think that was the one iconic thing that we brought back from that flight that could tell everybody, in just a photograph, exactly their position in life.

Astronomy: Did you have a feeling that it would become as iconic as it did when you were seeing it yourself, or not until you got back?

“I think [the Earthrise

image] was the one iconic

thing that we brought

back from that flight

that could tell everybody,

in just a photograph, exactly their

position in life.”

The astronauts took this photo of the jettisoned third stage of the Saturn V rocket after it had propelled them toward the Moon.

Humanity’s first view of the whole Earth came as Apollo 8 receded from our planet. This view shows south up, with South America at top center.

LaunchDecember 21, 1968,at 7:51 A.M. EST

Paci�c splashdownDecember 27, 1968,at 9:51 A.M. EST

Lunar orbit insertionDecember 24, 1968, at 3:59 A.M. EST

Trans-Earth injectionDecember 25, 1968,at 12:10 A.M. EST

Trans-lunar injectionDecember 21, 1968,at 10:47 A.M. EST Moon at launch

Moon at splashdown

Earth parking orbit

2

5

3

4

1


Lovell: We thought it was very important. . . . We thought that it would have meaning to those back on Earth. And [we were] very fortunate. When the word came down to do the flight, the three of us were in Downey, California, going over the spacecraft. And they called Frank back [to explain the mission changes].

So Frank listened. He said, “Well, OK, we just want to go around the Moon and come back again; let’s circumnavi-gate.” “No, no, no, no. You don’t get anything out of that for the landings,” [they replied]. “Well, we’re not tak-ing anything, no photogra-phy, no TV camera, nothing like that.” And they said, “You’ve got to be crazy.”

[He saw] his job was to beat the Russians, get around [the Moon], and they said, “No, no, this is not that at all. You gotta take pictures. We want the TV camera. . . . We all want that.” And so it slowly evolved that [Frank] got to be more and more really knowing the meaning of this particular flight.

Astronomy: When you’re on the farside of the Moon and getting ready to come back, did you have any concerns about whether the rocket

would fire? Neil and Buzz said that when they were on the surface, they chose not to think about what would happen if the lunar module rocket wouldn’t fire.

Lovell: I don’t think that any flight to the Moon and back, ever, [wondered] whether the engines would light again or not. I mean, you have to take that on faith. There is no alternative, that’s what’s going to happen. And it’s kind of funny. I was running the com-puter, and so we had a count-down on the computer with the exact time to light the engine. And I had my finger

on a thing called “proceed,” and I must have hesitated just a minute. Frank said, “Push the button, push the button.” So I pushed the button, and the engine came on, very, very gently at first, and then it slowly pushed us back in our seats so we knew the engine was running. And I could see on the computer the increase in velocity as we were going along, and I knew that we had to attain a certain velocity to escape from the Moon to come back to the Earth.

Astronomy: You had men-tioned before about how in America and around the

world, 1968 was a time of great upheaval. Apollo 8 came at the end of that long year and put a much different, and more positive, spin on that year. Did you have any sense at the time about how your mission was going to change many people’s minds about what the year had been like?

Lovell: No, we didn’t. As long as we were in the spacecraft coming back we only talked to one person, and that was the CapCom [the capsule communicator]. We did start to read newspapers on the ship that had picked us up to give us a feeling of really what

The Apollo 10 command module appears to the lower right of triangular Mount Marilyn on the southeastern shore of the Sea of Tranquillity.

Tsiolkovsky Crater sticks out on the lunar farside. The Apollo 8 astronauts were the first humans to see the farside with their own eyes.

The rugged lunar farside is pockmarked with craters and sports few of the large lava-filled basins seen on the nearside.

Apollo 8’s voyage to the Moon

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all happened. When we got to Hawaii, we were getting things from our wives, our friends, and just the people there.

But the sense of Apollo 8 took a little while to sink into me. We knew it was a winner, it was a success, but then the flow of telegrams started coming [in]. And the one which was iconic — you’ve probably heard [of it] — all it said was, “You’ve made 1968.” It gave us in three words just what had hap-pened. So throughout the years, up to now, this is really the high point of my space career. Even though 13 was more of a challenge, 8 was the very first one, the first expedition going to new lands. That was the one I like the most.

Astronomy: Last year the International Astronomical Union made it official and finally named one of the lunar features you used for navigation as Mount Marilyn, after your wife. Could you tell us about the mountain’s importance during that first lunar flight?

Lovell: Well, yes, let me lead up to that. While we were

training to go to the Moon on Apollo 8, we had photographs of the Moon. . . . As we looked at the nearside — and our job was to look for suitable land-ing spots through photogra-phy and eyesight — the gen-eral consensus of the people, the geologists, and everybody [else was they] wanted the first flight to land in the Sea of Tranquillity. That looked like a pretty good area; it was on the nearside of the Moon. And as I looked around and we planned our trajectories on the photograph, we came over this little triangular mountain, and it was unusual in the fact that it sort of stood out. It was on the shoreline of the Sea of Tranquillity. And so, during one of the days, I said, “I’m naming that Mount Marilyn, after Marilyn Lovell.” No one said anything. In fact, we put it in the flight plan and all that.

And on Apollo 8 we went over Mount Marilyn, and looked at the fact that it led the way into the Sea of Tranquillity. And then Mount Marilyn stayed on the paper-work that was followed up on 10 and 11, and . . . they started looking and said that this was a good spot. And the astro-physicists, the people that

were looking at the trajectory, said yeah, because that looks like if you start at 60 miles and do the initiation there, somewhere in that vicinity, you’re separated from the command module and you fire the lunar module engine, it will take you down into the areas that we want you to land, which is basically flat areas.

And so it turned up on the paperwork of Apollo 10, and they did their descent-abort mission. In fact, there’s a pic-ture taken from the lunar module looking back at the command module just after they passed Mount Marilyn, and behind the command module is Mount Marilyn. [See the photo on p. 33.] And then of course on 11 they came by and, sure enough, that’s what they had used — it was a steppingstone, initial point, of Apollo 11.

Well, it was there for years, informally, but it got a life of its own. . . . It was in books; it was in my book, of course; and it was in the early part of the movie Apollo 13 when the two characters, Tom Hanks and [Kathleen Quinlan], were looking up and she says, “Where’s my mountain?” “It’s up there.” And so around

2014, a good friend of mine, an astrophysicist by the name of Mark Robinson out in Arizona, said, “Let’s see if we can get the International Astronomical Union [IAU] to give it an official name.” So we applied the proper way. “No, no, no. I mean, come on, we’re naming these [craters] after astronomers, physicists, people like that.” So we got a very polite denial. And mean-while I had looked up all the mountains on the nearside, how they were named, and they were mostly very famous people. There was one moun-tain named after a woman, and it was pulled from mythology: Mount Agnes. And so I thought about it for a while. Then Robinson said, “Let’s try it again. Let’s really push it, because it has certain meanings to Apollo 11.” . . . And so we did.

And funny, there was agreement because other peo-ple in the IAU also started to turn their heads, and so it turned out that they finally named it and said, “Really, you know, there ought to be a little romanticism in the spaceflights. I mean, not

A camera aboard a U.S. Air Force plane captured the fiery re-entry of Apollo 8, as the first manned mission to the Moon plummeted through Earth’s atmosphere December 27, 1968.

“So from that day on,

in perpetuity, looking

down at me long after

I’m gone, will be this little

triangular mountain

named Mount Marilyn.”


everything strictly cut and dried . . . but here is something that relates itself to the first lunar landing. It’s well promi-nent there, it’s really not named as part of the moun-tain range Secchi. . . . But then they all agreed that they should name it Mount Marilyn. So from that day on, in perpetuity, looking down at me long after I’m gone, will be this little triangular mountain named Mount Marilyn.

Astronomy: That seems appropriate. Seven months after Apollo 8 you were on the beach with Charles Lindbergh watching Apollo 11 lift off. Could you tell us what it was like to spend that time with a fellow space pioneer or avia-tion pioneer?

Lovell: Charles Lindbergh was my idol during my growing-up days in the 1930s. I wanted to be [an aviator like he was]. And so as we were getting ready for Apollo 11, I was asked as backup commander to Neil . . . to escort Charles Lindbergh out to the beach. So I did. And we were talking about the upcoming flight and I told him, “Look at that spacecraft on top of that big rocket, the Saturn V.” I said, “This is a very ostentatious moment; I mean that space-craft is going to land on the Moon.”

He looked at it, and he kind of thought for a while, and he said, “You know something? Yeah, it’s going to be quite significant. But Apollo 8, that’s the flight that I will remember.” Because I think in his mind, he was thinking about the 34 hours from New York to Paris, that long journey the first time to go there. And he said Apollo 8 was the first one to make that 240,000-mile voyage to

the Moon. Their landing there is only the last 60 miles. And so I thought that was pretty nice of him.

Astronomy: I know you’ve done thousands of interviews. Is there any question that you haven’t been asked that you’ve always wanted to answer?

Lovell: No, I think that I have a different perspective on a lot of things from Apollo 8. It’s not a question, it’s something in my own mind, because you know normally, our world is only as far as the eye can see. Out in the country, maybe mountains or hills or

trees really express how far we [can see] because we’re a small body on a huge planet. And in cities, our world is defined by buildings. When you walk down the streets of Chicago, your world is really only as far as your eyes reflect off of the buildings. And in buildings, for instance, the building we’re in right now, our world is solely within these walls.

But on Apollo 8, when I looked out at the Earth for the first time, 240,000 miles away, my world suddenly expanded to infinity. I could put my thumb up — and I say this many times and in thousands

of talks — I could put my thumb up to the window and completely hide the Earth. And I suddenly real-ized that behind my thumb, on this little planet, was about 5 billion people. Everything I ever knew was behind my thumb, and I suddenly got a different perspective of my position in life. Because when I look back at the Earth and I realize it was only a small planet, one of nine inside the solar system, it was a mere speck in the Milky Way Galaxy, and it was lost to oblivion in the universe. And so it gave me a feeling of, “How do I get here,” that God must have really given man-kind a stage upon which to perform, and how that play turns out is up to us.

Senior Editor Richard Talcott

watched with rapt attention as

Frank Borman, Jim Lovell, and

Bill Anders made humankind’s

first journey to the Moon.

Above left: The Apollo 8 command module floats in the Pacific Ocean as swimmers from the USS Yorktown ready it to be hoisted onto the ship.

Above right: The command module rests on the deck after it had been pulled from the ocean.

Left: Navy personnel greet the Apollo 8 astronauts as they step on the deck of the Yorktown after their historic mission.

Mars slides past Neptune


Visible to the naked eye

Visible with binoculars

Visible with a telescope

MARTIN RATCLIFFE and ALISTER LING describe the solar system’s changing landscape as it appears in Earth’s sky.

December 2018: Venus shines brilliantly

SKYTHISMONTH

D ecember’s night sky features several treats. Skywatchers can antici-pate two fine planetary conjunctions: Mars

and Neptune pass exception-ally close to each other in the evening sky, while Mercury and Jupiter meet in morning twilight. Meanwhile, Venus shines at its brightest for the year. But December’s most promising event has to be the prolific Geminid meteor show-er, which peaks under a largely Moon-free sky.

Let’s kick off our tour with one of the month’s more chal-lenging planets. Saturn lies low in the southwest during

December, Mars appears con-spicuous in the southern sky. The Red Planet shines at mag-nitude 0.0 and dominates the background stars of its host constellation, Aquarius. As darkness falls, the ruddy object lies halfway to the zenith — nearly double its peak altitude at opposition this past summer.

As you gaze at Mars with your naked eye, you might assume it’s the only object of interest in Aquarius. But target the planet through binoculars and you can pick up the much fainter glow of Neptune. The distant ice giant lies 3.6° east-northeast of Mars on the eve-ning of the 1st. Although both worlds move eastward relative to the starry backdrop, Mars moves much faster. The dis-tance between the two drops by about 0.6° every day.

A quick calculation shows that the two should be nearly on top of each other within a week, and mathematics once again reveals its power. On the North American evening of December 6, Neptune lies 23'

evening twilight in early December. The magnitude 0.5 world appears as a lonely point of light in the gathering darkness. On the 1st, it stands about 10° high 45 minutes after sunset. A week later, on the 8th, it’s only 7° high at the same time. But a slender, two-day-old Moon accompanies it that evening. They lie 3° apart and appear beautiful through binoculars. The ringed planet succumbs to bright twilight within a week. It will pass on the far side of the Sun from our viewpoint at the begin-ning of January.

While twilight partially obscures Saturn in early

east-northeast of Mars. The two switch positions the fol-lowing evening, with Neptune 16' southwest of Mars. (The magnitude 6.1 star 81 Aquarii stands 12' north of Mars.) Although you’ll need binocu-lars or a telescope to spot magnitude 7.9 Neptune, you’ll rarely get a better guide than you’ll have these two nights.

The actual conjunction between the two planets occurs at 9:08 a.m. EST on the 7th, when Mars passes 2.2' north of Neptune. The two then lie below the horizon from North America, but observers in Eastern Europe and the Middle East will have front-row seats to the event.

This is the second close conjunction between these planets in a couple of years. On December 31, 2016, the two appeared slightly nearer to each other, though this month’s event occurs higher in a dark sky. The future isn’t as bright, however. You’ll have to wait nearly two centuries, until October 19, 2210, for

A Geminid meteor slices between Taurus (with brilliant Jupiter intruding) and Orion at the height of the 2012 shower. Observers should get another great show this year with the Moon out of the sky. AMIRREZA KAMKAR

Skygazers enjoyed the color contrast between ruddy Mars and bluish Neptune in January 2015. The two worlds meet again December 7. ALAN DYER

Mars

Neptune

ORION

URSA MAJOR

AURIGA

GEMINI

TAURUS

LEO

ProcyonRigel

Betelgeuse

Aldebaran

Capella

RadiantCastor

Pollux

December 14, 1 A.M.Looking high in the south

10°

Regulus

Geminid meteor shower


METEORWATCH

The Geminid meteor shower peaks the night of December 13/14. The waxing crescent Moon sets by 11 P.M. local time on the 13th, and you should have excellent views from then until twilight starts to paint the sky. The meteors appear to radiate from a point in northern Gemini. This region stands more than halfway to the zenith at 11 P.M. and passes nearly overhead between 1 and 2 A.M.

The Geminid shower ranks as one of the three richest showers of the year. But it benefits from the fact that its radiant climbs over-head from mid-northern latitudes, so observers under dark skies have a chance to see the maximum pos-sible rate of 120 meteors per hour.

Don’t stare at the radiant, how-ever. Any meteors you see there

Luna leaves the Geminids alone

— Continued on page 42

Geminid meteorsActive dates: Dec. 4–17

Peak: December 14

Moon at peak: Waxing crescent

Maximum rate at peak: 120 meteors/hour

Mars and Neptune to pass closer under a dark sky.

Although the worlds appear together these December evenings, Neptune lies 28 times farther from Earth. The ice giant’s large size only partially compen-sates for its greater distance. When viewed through a tele-scope, Neptune appears 2.3" across while Mars spans 9".

You won’t see any detail on Neptune beyond its blue-gray color. Mars is a different story. Sunlight illuminates 86 percent of its Earth-facing hemisphere, so its disk appears distinctly gibbous. And most scopes should reveal one or two dark markings.

Following the conjunction, Mars’ eastward motion carries it within 0.3° of 4th-magnitude Phi (ϕ) Aqr on December 12. A First Quarter Moon passes 4° south of the planet on the 14th. Mars crosses the invisible border between Aquarius and Pisces on the 21st and ends the year a few degrees southeast of

Marius Hills

RISINGMOON

It’s easy to see evidence of volca-nic activity on the Moon: Simply look at the large dark “seas” that populate the nearside. These maria are huge expanses of now-solidified lava that erupted from beneath the surface more than 3 billion years ago.

Besides the maria, Luna’s best volcanic features may be a field of domes known as the Marius Hills. This coarse, sandpaper-like terrain lies near the craters Marius and Reiner in the vast Oceanus Procellarum of the Moon’s western hemisphere. The hills see first light the eve-ning of December 19, about three days before Full phase.

You can’t help but notice Tycho’s spectacular ray system

and brilliant Aristarchus at this phase. Take some time to enjoy these features, but then boost your telescope’s magnification and shift your concentration to the far west. The Marius Hills lie just north of the equator along the terminator — the line that divides lunar day from night. Although prominent on the 19th, the hills become harder to see on the 20th. And by the 21st, the Sun’s higher elevation has wiped out the shadows necessary to observe this textured terrain.

How did these hills develop? Astronomers think the structures formed through multiple epi-sodes of volcanic activity. A few hundred steep-sided cone volca-noes first erupted on the scene

A land where volcanoes once ruled

when a huge bubble of magma welled up from below. Less-violent eruptions then built the dome structures. Finally, huge volumes of lava oozed out of

cracks and vents, filling much of the surrounding basin. NASA selected the Marius Hills as a tar-get during the Apollo program, but that mission was canceled.

N

E

Marius

Marius Hills

Reiner

Oceanus Procellarum

will have short trails because you’re seeing them coming almost head-on. Instead,

look for the longer trails you’ll see roughly 30° to 60° away from Gemini.

After the Moon sets the evening of December 13, observers under a dark sky could see up to two meteors per minute. ALL ILLUSTRATIONS:

ASTRONOMY: ROEN KELLY

Mars passes 2.2' from Neptune on December 7. The two won’t appear closer in a dark sky until the 23rd century.

OBSERVING HIGHLIGHT

This large area of volcanic hills stands out as the Sun rises over Oceanus Procellarum on December 19. CONSOLIDATED LUNAR ATLAS/UA/LPL; INSET: NASA/GSFC/ASU

CAMELO

PARDALIS

URSAMINOR

CASSIOPEIA

PERSEUS

URSA MAJOR

CEPHEUS

O

AQ

U

P I S C E S

TR

IAN

GU

LU

MAR

I E S

OR

IO

N

MO

NO

CE

RO

S

CA

NI

S M

IN

OR

LE

PU

S

TA

UR

US

E R I DA N U S

AN

DR

OM

ED

A

LYN

X

AU

RIG

A

GE

MIN

I

S C U L P T

P H O E N I X

C E T U S

F O R NA X

Polaris

NCP

M82 M81

M33

M31

M3

7M

1

M3

5

M42

M3

6

M38

Ald

ebaran

Pleiad

es

Rigel

Be

telg

eu

se

Hyades

Mira

Po

llux

Castor

Algo

l

SGP

Capella

NGC 253

NGC 869

NGC 884Uranus


STARDOME

Sirius

0.0

1.0

2.0

E

N

S

NE

SE

3.04.05.0

STARMAGNITUDES

STAR COLORSA star’s color depends

on its surface temperature.

• The hottest stars shine blue

• Slightly cooler stars appear white

• Intermediate stars (like the Sun) glow yellow

• Lower-temperature stars appear orange

• The coolest stars glow red

• Fainter stars can’t excite our eyes’ color

receptors, so they appear white unless you

use optical aid to gather more light

How to use this map: This map portrays the

sky as seen near 35° north latitude. Located

inside the border are the cardinal directions

and their intermediate points. To find

stars, hold the map overhead and

orient it so one of the labels matches

the direction you’re facing. The

stars above the map’s horizon

now match what’s in the sky.

The all-sky map shows

how the sky looks at:

9 P.M. December 1

8 P.M. December 15

7 P.M. December 31

Planets are shown

at midmonth

1

2 3 4 5 6 7 8

9 10 11 12 13 14 15

16 17 18 19 20 21 22

23 24 25 26 27 28 29

30 31

SUN. MON. TUES. WED. THURS. FRI. SAT.

LA

CE

RT

A

DRACO

LYR

A

SA

GI

TT

A

VU

LP

EC

UL

A

DE

LP

HI

NU

S

EQ

UU

LE

US

UA

RI U

S

CY

GN

US

P I S CI S

AU

STR

I NU

S

PE

GA

SU

S

T O R

AQ

UI

LA

CA

PR

IC

OR

NU

S

M57

Vega

M2

7

M1

5E

nif

Deneb

Fom

alhaut

Alt

air

Path of the Sun (ecliptic)

Mars


Open cluster

Globular cluster

Diffuse nebula

Planetary nebula

Galaxy

W

NW

SW

MAP SYMBOLS

Note: Moon phases in the calendar vary in size due to the distance from Earth and are shown at 0h Universal Time.DECEMBER 2018

Calendar of events

1 Venus is at greatest brilliancy (magnitude –4.9), 11 P.M. EST

3 The Moon passes 4° north of Venus, 2 P.M. EST

5 The Moon passes 1.9° north of Mercury, 4 P.M. EST

6 Mercury is stationary, 3 P.M. EST

7 New Moon occurs at 2:20 A.M. EST

Mars passes 0.04° north of Neptune, 10 A.M. EST

Asteroid Eros is at opposition, noon EST

8 Asteroid Harmonia is at opposition, 2 P.M. EST

The Moon passes 1.1° north of Saturn, midnight EST

9 The Moon passes 0.7° north of Pluto, 11 P.M. EST

12 The Moon is at apogee (251,765 miles from Earth), 7:25 A.M. EST

SPECIAL OBSERVING DATE

14 The annual Geminid meteor shower peaks before dawn under a Moon-free sky.

14 The Moon passes 3° south of Neptune, 9 A.M. EST

The Moon passes 4° south of Mars, 6 P.M. EST

15 First Quarter Moon occurs at 6:49 A.M. EST

Mercury is at greatest western elongation (21°), 7 A.M. EST

17 The Moon passes 5° south of Uranus, 11 P.M. EST

19 Jupiter passes 5° north of Antares, 9 P.M. EST

21 Mercury passes 6° north of Antares, 3 A.M. EST

Mercury passes 0.9° north of Jupiter, 10 A.M. EST

Winter solstice occurs at 5:23 P.M. EST

22 Full Moon occurs at 12:49 P.M. EST

24 The Moon is at perigee (224,353 miles from Earth), 4:49 A.M. EST

27 Asteroid Hebe is at opposition, 9 P.M. EST

29 Last Quarter Moon occurs at 4:34 A.M. EST

ILLU

ST

RA

TIO

NS

BY

AST

RO

NO

MY

: RO

EN

KE

LLY

BEGINNERS: WATCH A VIDEO ABOUT HOW TO READ A STAR CHART AT www.Astronomy.com/starchart.

PATHOF THE

PLANETS The planets in December 2018

PERAUR

TAU

ORI

CAE

C OL

ERI

LEP

LYN

GEM

CNC

MON

PUP

PYX

VEL

ANT

CRTHYA

SEX

LEO

OPH

HER

DR A

LYR

CEN

CRV

C OM

BO Ö

SER

VIR

LIB

SC OTEL

SCT

SER

LUP

C rB

CVnLMi

UM a

CMi

CM a

Objects visible before dawn

Celestial equator



Dawn MidnightMoon phases

Sun

Jupiter

Asteroid Harmonia reachesopposition December 8

Venus shines at its brightest before dawn in early December

Mercury shines brightly in the morning sky in mid-December Ceres

Pallas

Herculina

Comet 38P

Asteroid Hebe reaches opposition December 27

Juno

123456789

202122232425262728293031

Venus

MarsMercury

Ceres

Uranus

SaturnNeptune

Pluto

10"

S

W E

N

Jupiter

The planets in the sky

These illustrations show the size, phase, and orientation of each planet and the two brightest dwarf planets at 0h UT

for the dates in the data table at bottom. South is at the top to match the view through a telescope.


Planets MERCURY VENUS MARS CERES JUPITER SATURN URANUS NEPTUNE PLUTO

Date Dec. 15 Dec. 15 Dec. 15 Dec. 15 Dec. 31 Dec. 1 Dec. 15 Dec. 15 Dec. 15

Magnitude –0.5 –4.8 0.2 8.9 –1.8 0.5 5.7 7.9 14.3

Angular size 6.7" 32.9" 8.4" 0.4" 31.8" 15.2" 3.7" 2.3" 0.1"

Illumination 62% 37% 86% 99% 100% 100% 100% 100% 100%

Distance (AU) from Earth 1.003 0.508 1.120 3.329 6.201 10.912 19.271 30.080 34.574

Distance (AU) from Sun 0.367 0.719 1.434 2.641 5.350 10.061 19.864 29.939 33.701

Right ascension (2000.0) 15h59.7m 14h26.4m 23h18.3m 14h53.7m 16h39.4m 18h32.8m 1h46.9m 23h00.9m 19h25.7m

Declination (2000.0) –18°13' –11°31' –5°17' –9°51' –21°31' –22°42' 10°27' –7°22' –22°03'

This map unfolds the entire night sky from sunset (at right) until sunrise (at left).

Arrows and colored dots show motions and locations of solar system objects during the month.

Jupiter’s moonsIo

Europa

S

W E

N

Ganymede

Callisto

ILLU

ST

RA

TIO

NS

BY

AST

RO

NO

MY

: RO

EN

KE

LLY

SGR

SCT

SEROPH

AQL

HER

DR A

LYR

CYG

VUL

SGE

EQU

L AC

AQR

CAP

MIC

CAS

ARIPEG

PSC

CET

SCL

PHE

FOR

GRUSC O

TEL

PsA

C rA

Objects visible in the evening

Path of the Moon

Early evening

Sun

Uranus

Pluto

Saturn

Neptune

Mars

Asteroid Eros reaches opposition December 7

Mars passes 0.04° north of Neptune on December 7

Vesta

Comet 46P/Wirtanen should appear brightest in mid-December

78910111213141516171819

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

Callisto

Europa Io

Ganymede

Jupiter

Ceres

Mars

Uranus

Neptune

Saturn

Pluto

Venus

Jupiter

Jupiter

MercuryGreatest western

elongation isDecember 15

EarthWinter solstice is December 21


Dots display positions

of Galilean satellites at

7 A.M. EST on the date

shown. South is at the

top to match

the view

through a

telescope.

To locate the Moon in the sky, draw a line from the phase shown for the day straight up to the curved blue line.

Note: Moons vary in size due to the distance from Earth and are shown at 0h Universal Time.

The planets in their orbitsArrows show the inner

planets’ monthly motions

and dots depict the outer

planets’ positions at mid-

month from high above

their orbits.

ORION

PERSEUS

AURIGA

TAURUS Pleiades

Algol

Aldebaran

Path of Comet 46P/Wirtanen

Dec 11

13

15

17

19

21

N

E

5°

Comet 46P/Wirtanen

December 3, 1 hour before sunriseLooking southeast

C ORVUS

BO ÖTES

VIRGO

Arcturus

Spica

Moon

Venus

10°

Brilliant Venus meets the Moon


COMETSEARCH

Comet observers haven’t had it this good for a couple of years. Comet 46P/Wirtanen is a rela-tively active comet that makes its closest approach to the Sun this month just outside Earth’s orbit. And to top things off, we hit the timing almost perfectly: On December 16, Wirtanen swoops within 7.2 million miles of Earth, just 30 times the Moon’s average distance.

The comet’s peak brightness remains the key unknown. Conservatively, it will glow around 7th magnitude and be a decent binocular object. But some astronomers estimate it might reach 4th magnitude, which would make it visible to the naked eye under a dark sky. Either way, you should be able to follow changes to the dusty inner coma through a 4-inch telescope from the suburbs.

The comet also rides high in December’s sky. It resides

among the background stars of Taurus at closest approach, between the magnificent Pleiades star cluster (M45) and the 1st-magnitude star Aldebaran. Although this area remains visible nearly all night, it climbs highest in late evening.

Leading up to 16th, we are looking slightly down on the comet’s stubby, fan-shaped dust tail. If it also sports a tail of ion-ized gas, it should appear as a short spike of green or blue angled to the northeast as the solar wind carries the ions directly away from the Sun.

Significant changes occur in short order. Earth passes through Wirtanen’s orbit on the night of December 15/16. That means we see the tails edge-on and con-fined to a short, straight line. The best views come after 12:30 A.M. local time when the Moon sets.

Comet observers may also want to track 9th-magnitude

The year’s brightest comet stays up all night

EVENING SKY MIDNIGHT MORNING SKY

Mars (south) Uranus (west) Mercury (southeast)

Saturn (southwest) Venus (southeast)

Uranus (southeast) Jupiter (southeast)

Neptune (south)

WHEN TO VIEW THE PLANETS

— Continued from page 37

the latter constellation’s Circlet asterism. The Red Planet then glows at magnitude 0.5 and sets shortly before midnight local time.

Slow-moving Neptune remains in Aquarius through the end of the year. On Christmas Eve, it passes 15' due south of 81 Aqr. This star serves as a useful guide in the second half of December after Mars has moved on.

You can find Uranus on the opposite side of Pisces. This world actually begins December in the southwestern corner of Aries the Ram, but it

stands 1.6° north-northeast of this star in early December and moves to a point 1.3° almost due north by month’s end.

A telescope reveals the planet’s 3.7"-diameter disk and striking blue-green color. You

crosses into the Fish on the 3rd. Uranus glows at magni-tude 5.7, so technically it’s vis-ible with the naked eye from a dark-sky site, but your best bet is to search for it through bin-oculars or a telescope.

The challenge comes in finding the right area — there are no bright stars nearby to guide you. Start at 3rd-magnitude Beta (β) Arietis, which lies near the center of the Star Dome map on p. 38–39. Then move 12° due south and slightly west to locate 4th-magnitude Omicron (ο) Piscium. Uranus

can be forgiven for thinking Uranus has gained a moon the night of December 24/25 when a 9th-magnitude field star slides 1' to its south. Try to view the ice giant during the early evening hours when

Comet 38P/Stephan-Oterma. Our best views of this periodic visitor come in the morning sky during December’s first half,

when it lies roughly 10° from Gemini’s twin stars, Castor and Pollux. It makes its closest approach to Earth on the 17th.

This periodic visitor might reach naked-eye visibility near the Pleiades star cluster when it passes closest to Earth in mid-December.

Earth’s planetary “twin” shines brightest before dawn in early December, but it looks most spectacular when the crescent Moon passes by on the 3rd.

10°

December 15, 45 minutes before sunriseLooking southeast

VIRGO

LIBR A

OPHIUCHUS

SC ORPIUS

Spica

Venus

Mercury

Jupiter

Path of Juno

Dec 16

11

16

21

26

31

ERIDANUS

17

24

22

21

N

E

0.5°

Catch Juno near its historic best

Mercury puts on a predawn show

GET DAILY UPDATES ON YOUR NIGHT SKY AT www.Astronomy.com/skythisweek.


Minor planet 3 Juno continues its brief reign as the brightest asteroid. Glowing at magni-tude 7.6 in early December, the 170-mile-wide, potato-shaped space rock dims to magnitude 8.2 at month’s end. That makes it bright enough to see with binoculars from the suburbs and an easy target through even the smallest telescope.

Juno reached opposition and peak visibility in mid-November. As Earth sprints ahead of it on the solar system’s orbital race track, Juno climbs higher in the southeastern sky after darkness falls. The major-ity of main belt asteroids orbit the Sun in roughly the same plane as the planets, known as the ecliptic, but Juno tilts 13° to

this plane. That places it well south of the ecliptic this month, plying the relatively star-poor waters of the great celestial river Eridanus, located to the west of Orion.

Use the star chart below to get to the right vicinity. (Or, if you use an equatorial mount, simply slew 28° south of the Pleiades star cluster.) Once you arrive, Juno will be one of the brightest points of light in the field of view. Unlike the crowded, uniform star fields you find closer to the Milky Way, here the uneven background with its wide range of star brightnesses proves useful. You should be able to track Juno’s night-to-night motion with a modest magnification of 50x.

LOCATINGASTEROIDS

Juno fords a cosmic stream

it peaks some 60° above the southern horizon.

Although the evening sky has its charms, the morning sky offers December’s three brightest planets. Even in this dazzling company, Venus stands out. The inner planet peaks at magnitude –4.9 December 1 and fades only slightly (to magnitude –4.6) by month’s end. It dominates the southeastern sky from the time it rises before 4 a.m. until shortly before sunrise more than three hours later.

Be sure to catch this bea-con when a slender crescent Moon hangs 5° above it the morning of December 3. First-magnitude Spica — Virgo the Maiden’s brightest star —appears 7° to the right of this pair. Venus crosses from Virgo into Libra on December 13 and remains there until the end of 2018.

Viewing Venus through a telescope against a dark sky can be dazzling, so experi-enced observers often wait for the onset of twilight. The planet won’t disappoint. Its disk spans 40" and appears one-quarter lit December 1; by month’s end, the planet’s diameter has shrunk to 26" while its phase has fattened to nearly half-lit.

Mercury joins Venus in the morning sky. The inner-most planet reaches greatest elongation December 15, when it lies 21° west of the Sun and climbs 10° above the southeastern horizon 45 min-utes before sunrise. Mercury then shines at magnitude –0.4 some 24° to Venus’ lower left.

Mercury sinks deeper into twilight during December’s second half. As it descends, Jupiter rises to meet it. On December 21, they stand 0.9° apart. At magnitude –1.8, Jupiter appears more obvious than magnitude –0.5 Mercury. Enjoy this pretty conjunction starting about 45 minutes before sunup, when the pair lies 8° above the horizon. Those with eagle eyes, or bin-oculars, may notice the 1st-magnitude star Antares 5° to Jupiter’s lower right.

Like Venus, Mercury tran-sitions through a variety of phases — it just does so more quickly. On December 5, Mercury spans 9" and is one-quarter lit. It appears exactly half-lit on the 11th, although its diameter has shrunk to 7". Its phase waxes to gibbous after this, reaching 63 percent illumination at greatest

elongation. And by the time Mercury passes Jupiter on the 21st, it sports a 6"-diameter disk that’s 77 percent lit.

Jupiter shows none of the dramatic changes the two inner planets do. Its disk spans 31" at the time of its conjunc-tion with Mercury and grows barely 1 percent by month’s end. Although the giant

Martin Ratcliffe provides plane-

tarium development for Sky-Skan,

Inc., from his home in Wichita,

Kansas. Meteorologist Alister

Ling works for Environment

Canada in Edmonton, Alberta.

planet’s low altitude washes out atmospheric detail, conditions will improve dramatically in January.

The innermost planet rises nearly two hours before the Sun at its peak December 15 and stands out in the twilight glow. Six days later, the small world has a spectacular conjunction with giant Jupiter.

December’s brightest asteroid takes a sharp turn northward in December as it navigates the shoals of northern Eridanus the River.


Interested in observing a red dwarf, supernova remnant, or galaxy cluster? We’ve got you covered. by Alan Goldstein

Explore nearbyDEEP-SKY GEMS

Red dwarf Barnard’s Star (6 light-years)The most common stars in the Milky Way are not visible to the naked eye. Red dwarfs are inherently dim, and only those located near us are bright enough to be seen through the typi-cal hobbyist telescope. The closest is Proxima Centauri, just 4.2 light-years from Earth. At 11th magnitude, it is 100 times fainter than the naked eye can see. It is also deep in the southern sky, below the horizon for most U.S. observers.

The next closest red dwarf, at 6 light-years away, is Barnard’s Star, discovered by Edward Emerson Barnard in 1916. It has the distinction of being the fastest star (known as “proper motion”) in the sky relative to the Sun. Since Barnard’s Star was discovered, it has moved 17.7'. That’s slightly more than half the Moon’s appar-ent diameter. That may not sound like much, but compared to the other stars, it’s haulin’ hydrogen!

Observing tip: Use a star chart to pick this 9.5-magnitude star out of a rich star field.

he deep-sky observer’s neighborhood is kind of like yours. You know the house, grocery store, movie theater, beach, and mountain closest to your home. Deep-sky

observers know the closest stars, nebulae, clusters, and galaxies in their solar neigh-

borhood. But travelers can’t drive to visit these objects; instead, the light comes to them. Some are visible to the naked eye, others require binoculars, and a few necessitate a telescope — though none requires large optics.

You might think the closest deep-sky objects are dis-tributed randomly across the sky, but that’s not the case. They are scattered in right ascension — some are “up” at any given time of the year. But oddly enough, there is a strong bias in declination. Of the nearest celestial objects featured here (see table on page 46), only two — the Hyades cluster and Andromeda — are north of the celes-tial equator. Three on the list — a red dwarf star, a mul-tiple star, and a supernova remnant — are deep in the southern sky, beyond the range of U.S. observers. For those, the selection chooses the nearest suitable targets for mid-northern latitude observers. The remainder lie slightly south of the celestial equator.

T

Barnard’s Star: Note the red dwarf’s change in position between 1950 (right) and 2010 (left).

OBSERVING TARGETS

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White dwarf Sirius B (8.6 light-years)Imagine a hot star the size of Earth, but with the mass of the Sun. The transition begins as a Sun-like star becomes a red giant, like Aldebaran (Alpha [α] Tauri). It then ejects its outer layers to form a planetary nebula, and eventually settles down as a white dwarf. Our Sun is destined to become a white dwarf in about 5 billion years.

In the meantime, the closest white dwarf, Sirius B (Alpha Canis Majoris B), is only 8.6 light-years away. It is the companion of Sirius A, the brightest star in the night sky. Originally, Sirius B was brighter and more massive than Sirius A, but it aged faster and evolved into a white dwarf around the time the Cretaceous raptor Deinonychus prowled North America. Although it is brighter than Barnard’s Star, the glare of its luminous companion makes it a challenge to see. It’s currently about 10" east of the primary,

approaching the most distant part of its 50-year orbit. That means it is easier to see now than it will be in 25 years.

Observing tip: Let Sirius drift through your eyepiece’s field of view; the companion lies to the east and will follow. High magnification and a steady sky are your friends. And light pollution won’t have much effect on your view.

Double star 61 Cygni (11.4 light-years)Double stars orbit around a gravitational center called the barycenter. Such systems may have similar stars — or different, if one has greater mass and evolves more quickly than the other.

61 Cygni is an example of a system with two similar stars. It’s not the closest binary to the Sun (Alpha Centauri and Sirius are closer) but is the nearest one north of the

celestial equator. This system’s claim to fame is being the first to have its distance measured with a fair degree of accuracy. In 1838, using the stellar parallax method, Friedrich Wilhelm Bessel came up with 10.3 light-years — though today’s research shows it to be 1.1 light-years more distant. This is a pair of K-type dwarf stars that complete an orbit in 659 years. Like

Sketch of 61 Cygni

Hyades cluster

JEREMY P

EREZ


Barnard’s Star, it’s a “fast” mover — the fastest visible to the naked eye. With a pri-mary of magnitude 5.2 and a secondary that glows at magnitude 6.0, it’s hard to pick out with the naked eye under an urban sky.

Observing tip: The stars are separated by a generous 28", so it’s easy to resolve them through a small telescope and distinguish their orange hue.

Open cluster Hyades (153 light-years)The famous saying about “not seeing the trees for the forest” can also apply to groups of stars called open clusters. Just as a foreground tree can blend into a forest when viewed from afar, a foreground star can blend into a open cluster when they are both viewed along the same line of sight. Such is the case for the Hyades.

The Hyades, which forms the head of Taurus the Bull, is the nearest open cluster. Because it’s only 153 light-years from us, it has an apparent diameter greater than 5°. Its true diameter exceeds 20 light-years. Even after an estimated 625 million years, the stars are still moving together. Aldebaran, the brightest star in Taurus, is only 65 light-years away. However, its apparent association with the Hyades is simply a coincidence.

Observing tip: The best views of the Hyades usually come through binoculars or a small rich-field telescope.

Planetary nebula Helix Nebula (690 light-years)In about 5 billion years, the Sun will shed its outer layers of gas to become a planetary nebula, leaving behind a white dwarf in the center. Through the same process, an ancient star expelled varying densities of ionized gas — especially oxygen — to give this next nebula its name.

The Helix Nebula (NGC 7293) is an older planetary, so the gas has traveled far enough to appear as a ring (because the greatest density of gas in the sphere we see is along the edge) about 2.5 light-years in diameter. Its name comes from the irregu-lar brightness that gives it the appearance of a helix (like a spring) when viewed from the end. With a telescope, it appears as a ghostly smoke ring in Aquarius.

Observing tip: The Helix Nebula has a low surface brightness, so a dark sky is essential. This is a rather large object (slightly smaller than the Full Moon), visible through binoculars, where it looks like a disk. The darker interior is visible with small telescopes.

Emission nebula Orion Nebula (1,300 light-years)Spiral galaxies like the Milky Way are full of light-emitting gas clouds, called emis-sion nebulae, that eventually condense to form clusters of stars. These swirls of ion-ized hydrogen, other elements, and dust are stellar nurseries, resembling the Sun’s

birthplace some 4.5 billion years ago.We see the nearest emission nebula, the

Orion Nebula (M42), because it’s illumi-nated by the Trapezium, a tight group of luminous, hot stars that have formed within it. Their intense radiation makes the gas glow, like a fluorescent lightbulb.

Observing tip: M42, located in the sword of Orion, is visible to the naked eye. If you view through a large telescope, the nebula may appear greenish. The vibrant colors in beautiful photos of this object are too faint for the human eye to register.

Type Object Distance

Red dwarf Barnard’s Star 6 light-years1

White dwarf Sirius B 8.6 light-years

Double star 61 Cygni 11.4 light-years2

Open cluster Hyades 153 light-years

Planetary nebula Helix Nebula 690 light-years

Emission nebula Orion Nebula 1,300 light-years

Supernova remnant Veil Nebula 1,470 light-years3

Globular cluster M4 7,000 light-years

Large galaxy Andromeda 2.5 million light-years

The table above lists the nearest object that is visible from mid-northern lati-tudes for each type of object; however, some types of objects have closer counterparts deep in the southern sky. For those, see the footnotes below.

1Proxima Centauri (4.2 light-years)2Alpha Centauri (4.2 light-years)3Vela supernova remnant (815 light-years)

NORTHERN NEIGHBORS

Helix Nebula (NGC 7293)

Orion Nebula (M42)

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Supernova remnant Veil Nebula (1,470 light-years)The Veil Nebula has many names and several NGC numbers because it takes up nearly 3° of the sky. (By comparison, a Full Moon takes up 0.5°.) It forms a partial ring of ionized gas in Cygnus that shows incredible detail with modest to large apertures under dark skies. The progenitor was a massive star that lit up the night sky when it exploded some 3,000 to 8,000 years ago.

Observing tip: Under a dark sky, the Veil Nebula may be glimpsed with high-quality binoculars. It looks impressive through a wide-field telescope with enough contrast to bear magnification well.

Globular cluster M4 (7,000 light-years)Scattered around the Milky Way like mosquitos around a skygazer are spheri-cal groups of stars called globular clusters. Their origin is far different from open clus-ters, forming at the same time as the galaxy. Some are associated with the cores of dwarf galaxies ripped apart as they collided with the Milky Way. The distance between stars in the cluster may average about 1 light-year, but near the core, they may be only billions of miles apart. (A light-year is about 5.9 trillion miles, or 9.5 trillion kilometers.)

M4, located close to Antares (Alpha Scorpii), is a favorite of many amateur astronomers for several reasons: It’s easy to find, it’s bright, and its stars can be resolved in telescopes with apertures as small as 6 inches. This ball of stars is 75 light-years in diameter with an estimated age of 12.2 billion years. You are looking at stars nearly three times older than the Sun!

Observing tip: This is one of the easiest globular clusters in the sky to resolve. To spot it, look for a bright bar of stars bisecting the cluster.

Large galaxy Andromeda Galaxy (2.5 million light-years)The Milky Way is the second-largest member of the Local Group, a cluster con-sisting of nearly 60 galaxies. Only three galaxies — the Andromeda Galaxy (M31), the Pinwheel Galaxy (M33), and the Milky

Way — are large; the rest appear as mere wisps by comparison.

The Andromeda Galaxy is the closest large galaxy. Somewhat bigger than our home galaxy, it spans 220,000 light-years and contains an estimated 1 trillion stars. (For comparison, our galaxy contains 200 to 400 billion stars.) M31 is inclined 18° from edge-on, which intensifies its bright-ness, just like the Helix Nebula is brightest where we look through its edge. At magni-tude 3.5, it can be seen with the naked eye in suburban skies. Under dark skies, Andromeda spans a whopping 3.1°, or roughly the width of six Full Moons.

Observing tip: M31’s dwarf elliptical companions, M32 and NGC 205, are visible in the same field of view through a small telescope.

If you like creating themed observing lists, this is a place to start. Use the next cloudy night as an opportunity to research other targets. What is the closest red giant? The nearest O-type star? Dark neb-ula? Peculiar galaxy? Dwarf elliptical? Your choices are vast because the universe has incredible diversity with options for every observer — from those using their naked eyes to those viewing through behemoth telescopes. Start with the objects in this list, and then take it to the next level.

Alan Goldstein has been observing deep-sky

objects for 40 years and writing about them

for nearly as long.

Andromeda Galaxy (M31)

Veil Nebula

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The effects of light and dark on the lunar terminator offer some great observing fun. by Phil Harrington

Observe shadow playObserve shadow playp yp y on the on the MoonMoon

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T he Moon’s terminator — the line that divides the dark part from the sunlit area — is a fas-cinating sight through all tele-scopes. Here, along the lunar

sunrise/sunset line, lighting can transform familiar features into strange shapes that disappear when the Sun climbs higher in the Moon’s sky.

Some observers refer to such strange lighting phenomena as clair-obscur effects. The term is adopted from an oil painting technique developed during the Renaissance that uses varying shades of colors and contrasts to create dramatic, three-dimensional effects. The Italian term chiaroscuro (translated as “light-dark”) is also used often to describe the same technique.

I have collected a baker’s dozen lunar clair-obscur effects to whet your appetite. To help zero in on when to look, each description includes the prime time of vis-ibility in terms of days after New Moon (often called the Moon’s age). Be aware, however, that some are more challenging than others. A few remain visible for sev-eral nights in a row, while others disappear after a few hours because the Sun’s chang-ing angle wipes them from view.

Another factor that makes viewing some of these features trickier than others is that they require knowing more than just lunar age. You also need to know the colongitude of the Sun. Colongitude is the exact selenographic (lunar) longitude of the “morning” terminator, the line of sunrise on the Moon. Like longitude on Earth, colongitude is measured in degrees.

By definition, the colongitude equals 0° when the Sun stands exactly above lunar longitude 90°. That alignment occurs approximately at First Quarter, but can

actually take place several hours before or after that moment due to libration — the Moon’s slow back-and-forth wobble as it orbits Earth.

Fortunately, you can use a freeware pro-gram to find the Sun’s colongitude at any given time: www.internetsv.info/MoonCalc.html. The only data you’ll need to enter is the date and the Universal Time.

LUNAR X(Lunar Day 6.9) Let’s begin our hunt with the one clair-obscur effect that has prob-ably garnered more attention in online discussion forums than any other. First noticed in August 2004 by Canadian amateur astronomer David Chapman, the Lunar X — also known to some as the Werner X or the Purbach Cross — is easy to see if you look in the right place at the right time. The shape is formed by the confluence of four lunar craters: Purbach, La Caille, Regiomontanus, and Blanchinus. Purbach forms the eastern side of the X, while Blanchinus creates the western side. La Caille forms its northern boundary, and Regiomontanus marks the southern section. One of the X’s namesakes, the 43-mile-wide (70 kilometers) Werner crater, does not contribute to the feature directly. Instead, as Chapman suggests, “Werner is the closest well-lit crater and makes an obvious beacon for observers.”

If the timing is right, it’s fascinating to watch the Sun rise over the X, slowly unveiling its ragged form over the course of an hour or so. The first rays catch the

southeastern wall of Purbach. As the Sun climbs higher in the lunar sky, the X grows as Purbach’s northeastern wall is lit, even-tually merging with the southeastern rim to form one side of the X. The southwest-ern side of Blanchinus next sees the light, followed finally by La Caille to complete the X. If you are even a few hours late, the shadowing effect is lost and the X-cellent illusion disappears.

High magnification is not required to see this effect. In fact, you can even spot it through steadily held binoculars.

LUNAR V(Lunar Day 6.9) While you’re enjoying the X, be sure to catch the V, which lies nearby. That’s right, we have another letter of the alphabet visible at the same time just north of the X. The V is sandwiched between Mare Vaporum to its north and Sinus Medii to its south. This puts it smack dab in the center of the Moon’s disk.

The so-called Lunar V is formed by low-angled sunlight spangled across several small craters. The largest, 14-mile-wide (23 km) Ukert, forms a portion of the V’s western edge, while a pair of intersecting ridges create the rest of this edge as well as the eastern edge. Although the Lunar V is every bit as obvious as the Lunar X, it hasn’t quite attracted the same level of attention among devout luna-tics.

ARIES’ HOOFPRINT(Lunar Day 6.9) As the X and V draw your attention, shift your concentration just


east of the V and Ukert Crater to a shadow feature nicknamed Aries’ Hoofprint. First mentioned by name a decade ago in an edition of Astronomy’s email newsletter, Aries’ Hoofprint is formed from an intri-cate combination of brightly lit mountains and dark lava channels. Some call this striking chiaroscuro the Horseshoe, while others prefer the Lunar Lips. If we want to assign a letter to it, I suppose the Lunar U might be the closest approximation. But I favor the hoofprint analogy. On older lunar maps, you may find the area labeled Mount Schneckenberg, which translates to “Snail Mountain.” That odd name, bestowed by the International Astronomical Union, has since been retired.

LUNAR L(Lunar Day 7.3) Continuing our game of lunar alphabet soup, return to our satellite about an hour past the X’s peak time and scan southward along the terminator. Can you spot a slanted L just beyond Stofler Crater? The Lunar L was first noticed — to my knowledge anyway — by Steve Bellavia of Mattituck, New York. The L is formed from a combination of the eastern walls of craters Deluc, Deluc H, and Deluc D combined with a ridge to their south, all just coming into light.

NESSIE(Lunar Day 7.3) You’re familiar with the Loch Ness monster and the infamous

This image of the First Quarter Moon shows the positions of the Lunar V

(top), the Lunar X (center), and the Lunar L. The best time to

observe these three clair-obscur effects is when

the Moon is seven days old (that is,

seven days past New Moon).

STEVEN BELLAVIA

This shadow falling on the floor of Ptolemaeus Crater may not have come from the Loch Ness monster, but that didn’t stop this photographer from dubbing it “Nessie.” JOE ADLHOCH


photo purporting to show the creature’s silhouetted head and neck rising out of the loch’s waters, right? While that photo has been discredited, we can find Nessie’s shadow extending onto the northeastern side of the crater Ptolemaeus’ floor as the Sun rises higher in its sky. Named by Colorado amateur Joe Adlhoch, the effect is due to the combined shadow of the crater’s jumbled rim and the small interior crater Ammonius. Try

a magnification of 150x or higher for the best views.

LUNAR CITY(Lunar Day 8) On July 12, 1822, German physician and astronomer Baron Franz von Gruithuisen was observing through his 2.4-inch refractor when he thought he saw something unusual north of the partially flooded crater Schröter. The area is com-posed of a series of ridges emerging from

the surrounding Mare Insularum. A cen-tral ridge combines several parallel ridges spread diagonally to either side to create a unique herringbone pattern. As the low angle of the Sun lit the region, Gruithuisen interpreted what he saw as a city, complete with buildings, streets, walls, and a temple. He christened his discovery Wallwerk. Take a look the next time the Sun is rising over this area and see if you can imagine Gruithuisen’s “city.”

HESIODUS SUNRISE RAY(Lunar Day 8.3) Look along the terminator the night after First Quarter for the craters Pitatus and Hesiodus, which touch one another. As the Sun just rises in their sky, a gap in the adjoining walls casts a long sun-rise ray that looks like a searchlight beam across the otherwise shadowed crater floor. Crank up the magnification past 100x to examine the ray’s appearance.

EYES OF CLAVIUS(Lunar Day 8.5) Clavius is the third-largest lunar crater visible from Earth. You’ll also find several craters on its floor, which spans 136 miles (225 km). When light from the rising Sun first strikes the rims of two of these, known as Clavius C and Clavius D, it looks as though there are two hollow eyes staring up from Clavius’ shadowed floor. Binoculars are enough to see Clavius looking intently back at you.

QUINCUNX(Lunar Day 8.7) If you’re familiar with dice, then you’ve seen a quincunx even if you didn’t know it by name. A quincunx is an arrangement of five objects, with four at the corners of a square or rectangle and the fifth at its center. The best example of a quincunx is the five on a die. For the pur-poses of this story, the Moon rolls the dice every time the Sun rises over the mighty crater Copernicus. Just to its north, several peaks in Montes Carpatus poke up from the surrounding plain. As sunlight begins to slip down the wall of Copernicus, it also just strikes the five highest mountain peaks, lighting them up in an almost per-fect quincunx pattern. The Quincunx was first spotted, and subsequently christened, by Michael Rowles of Crofton, Maryland, on the evening of May 11, 2011.

EIN MOUNTAINS(Lunar Day 9) In case you missed the Quincunx, those same Montes Carpatus morph into a pattern resembling the let-ters E-i-N as the Sun continues to rise in

When the Moon is 8½ days past New, sunrise above Clavius Crater causes its two largest craterlets, Clavius D (the larger one) and Clavius C, to form the Eyes of Clavius. This image was taken March 13, 2011, at 19h44m UT. DAMIAN PEACH

The larger Moon image locates Hesiodus Crater, and the smaller image zooms in to reveal the well-defined Hesiodus Sunrise Ray (in the smaller crater to the left of Pitatus Crater at center). STEFAN SEIP/ASTROMEETING.DE

The Lunar City

MoonMaiden

Quincunx

Sinus Iridum

Lunar V

Ptolemaeus

Mare Nubium

HesiodusSunrise Ray

Eyes of Clavius Lunar L

Lunar X

Straight Wall and Huygens’ Sword

EiN Mountains

Aries’ Hoofprint

Nessie


their sky. The “E” is actually formed by the shadows of three peaks cast onto the adja-cent valley, while the “i” and “N” are cre-ated by light striking the sides of adjacent mountains. As its discoverer Joe Adlhoch points out, the E-i-N effect is most obvious in the inverted view of a reflector.

MOON MAIDEN(Lunar Day 11) One of the most striking lunar features visible between the waxing gibbous phases right through the wan-ing crescent is Sinus Iridum, the Bay of Rainbows. The bay is actually the remains of a large impact crater that was partially submerged after molten lava from Mare Imbrium breached its southern wall about 3.8 billion years ago.

The southwest end of the bay, where the crater rim sinks below the now-solidified mare, is named Promontorium Heraclides. Astronomers call the northeastern tip Promontorium Laplace.

When he gazed toward Promontorium Heraclides in the late 1670s, the renowned Italian astronomer Giovanni Cassini imag-ined a Moon Maiden: the profile of a wom-an’s head with hair flowing behind her as she looked across the bay toward Plato Crater. Can you see her, too? There’s a twist. Unlike some of the other clair-obscur effects that take exceptional condi-tions to be seen, the Moon Maiden is at her best when viewed through a small tele-scope and seeing (atmospheric steadiness) is poor. That will soften the surface enough to let you see her overall form. With optics that are too sharp or seeing that is too good, her form resolves into its individual components, and her appearance is lost.

Come back to this spot during the wan-ing crescent phase, and the Moon Maiden

will be gone. But in her place, the shadow created by the jagged profile of the Juras Mountains, which mark the perimeter of Sinus Iridum, falls onto the smooth floor of the bay to create what some call the Lunar Buzz Saw (Lunar Day 24.6).

STRAIGHT WALL AND HUYGENS’ SWORD(Lunar Day 21) One of my favorite lunar targets is the Straight Wall, known more properly by its official name Rupes Recta. While fault lines on Earth are most often

associated with plate tectonics, Rupes Recta was formed when a portion of Mare Nubium succumbed to subterranean pres-sures and buckled. The area to the west of Rupes Recta sheared off and dropped more than 1,000 feet (300 meters) along the fault line that extends for 70 miles (113 km) from tip to tip. On Lunar Day 8, the “wall” is in shadow, turning it into a black line that looks almost too straight to be natural. On Lunar Day 21, however, sunlight fully illu-minates the fault’s face, causing it to gleam.

Just south of Rupes Recta lies a small clump of jumbled terrain and a half-buried crater. The 17th-century astronomer Christiaan Huygens, credited with discov-ering Rupes Recta, likened the jumble and half-crater to the handle of a sword, with Rupes Recta forming the blade. Although a better allusion is that of a fencer’s foil, we know the combined appearance today as Huygens’ Sword. The sword is most strik-ing at lunar sunset.

Seeing these clair-obscur features will take some persistence and favorable sky conditions. For these challenges, though, you won’t have to travel to a dark site. Good luck!

Phil Harrington is a contributing editor

of Astronomy who loves to point different

telescopes at the Moon.

Use this guide to locate the general area of all the targets in this story. CONSOLIDATED LUNAR ATLAS

Rupes Recta, commonly called the Straight Wall, stretches for 70 miles (113 km) just to the east (right in this image) of the double crater Birt and Birt A. West (left) of Birt is a 30-mile-long (50 km) rille known as Rima Birt. Just below the Straight Wall is the jumbled terrain and half crater the author described, which form the handle and guard (with Rupes Recta being the blade) of Huygens’ Sword. BRIAN FORD

Birt


Mark Hanson admits he was never a stellar student, but his photography is out of this world.

Meet an expert in remote astroimaging

My fascination with space started in high school, when I “borrowed” the Astronomy magazines from my science classroom to look at the amaz-

ing pictures. (Sorry, Ms. Z., that you never saw those magazines again.) I remember having so many questions about how the pictures were taken. What type of tele-scope was used? How deep into space were those objects? How do you take such spec-tacular pictures of something so far away?

I wasn’t a horrible student, but I excelled only at the subjects that interested me — like space science. Looking back, I guess this makes a lot of sense, as I still dive into my passions fully, with little help from more formal academic settings.

First stepsFifteen years after high school, in the late 1990s, I toyed with the idea of taking my own pictures of space, albeit with limited funds. With what little I knew at the time, I started taking pictures of aurorae with a film camera. Then I took pictures of the Milky Way. Later, I graduated to my backyard setup: a homemade equatorial platform with my film camera duct-taped to the eyepiece of a Dobsonian telescope. It did the trick at the time. I still remember seeing the first image of the bands of color in Jupiter’s atmosphere. Next were the rings of Saturn. I was hooked.

Around that time, I learned about our local astronomy club, the Madison Astronomical Society (MAS). MAS had a dark-sky site — Yanna Research Station (YRS) — and permanent telescopes. There I met the late Richard A. Greiner (“Doc”),

and my life changed. Doc was a retired engineering professor from the University of Wisconsin-Madison and already well known in the astronomy community. He saw my passion for learning and began to teach me the mechanics of telescopes, mounts, cameras, and roof controllers. There were many nights when I served as his telescope mechanic out at YRS while he gave me instructions over the phone.

My passion became an obsession under Doc’s guidance. As a beginner, there was so much to learn. In 2003, I took my first trip to New Mexico Skies in Mayhill, New Mexico, where I met Mike and Lynn Rice. I was so excited about having the site’s 6-inch refractor all to myself, and Mike let

1. The author poses near London’s Royal Observatory in Greenwich during a visit to accept first place in the robotic telescope category of the 2014 Astronomy Photographer of the Year competition.

2. M27, or the Dumbbell Nebula, is shown here imaged with a 14.5-inch RCOS telescope on a Paramount ME II Mount and an SBIG STX 16803 camera. The author also recently added data from a 24-inch PlaneWave telescope. This Hα/OIII/S2/LRGB image has exposures of 6, 10, 6, 4, 2.7, 2.7, and 2.7 hours, respectively. Unless noted, all data were calibrated, aligned, and combined in CCDStack, with all other processing done using CC Photoshop and PixInsight.

3. Mark frequently uses the 24-inch telescope at Stellar Winds Observatory in New Mexico to take his stunning images.

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me put my DSLR on it. While I was on the trip, Lynn showed me my own photograph of the Witch Head Nebula (IC 2118) in the August 2003 issue of Astronomy. I couldn’t believe it.

Going remoteAlso around this time, Doc, MAS mem-bers Greg Sellek and Matt Mills, and I were setting up the Doc Greiner Research

Observatory (DGRO) to run remotely. This was a pretty big deal in 2005. I col-lected data for processing, while Matt and Greg looked for asteroids. The DGRO has moved a few times over the years, finally settling in what is now Dark Sky New Mexico (DSNM) near Animas. Once we had our setup at DSNM running smoothly, I began helping others set up their obser-vatories, and I have become knowledgeable

4. This obscure part of the Veil Nebula is sometimes called the Leaping Leopard Nebula. Simeis 3-210 is a long, thin filament at the extreme southern end of the Veil Nebula and is virtually unknown. To the author’s knowledge, it has never before been imaged at this resolution, which was achieved with a 24-inch PlaneWave telescope on a PlaneWave Ascension 200HR German Equatorial Mount, using an SBIG STX 16803 camera. This Hα/OIII/LRGB image contains exposures of 10, 11, 3.75, 3.75, 3.75, and 3.75 hours, respectively.

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about performing maintenance on a vari-ety of scopes. Through doing this, I’ve met some remarkable people.

One of these people is Stan Watson from Stellar Winds Observatory (SWO) at DSNM. We became friends while I was doing some maintenance at his facility. Now I’m also a part of the team there. These days, I do most of my imaging using SWO’s 24- and 17-inch scopes. Recently, three images I took with these scopes were short-listed in the Insight Astronomy Photographer of the Year contest in London.

Science, too?Amateur astronomers can definitely con-tribute to science. After all, you never know what will end up in your images.

In 2014, I was approached by David Martinez-Delgado, a Spanish astrophysicist working on the Stellar Tidal Stream Survey at the Max Planck Institute for Astronomy in Heidelberg, Germany. He saw some-thing in my data that he hadn’t seen before and asked if I would share it with him. It was a newly discovered stellar stream in a nearby spiral galaxy, NGC 3628. Now I

collaborate with him regularly by receiving specific targets to image so that data can be included in his group’s research papers.

I have really started to enjoy this aspect of imaging. Whenever I image a new stream target, I have a hard time sleeping until I get those first 10 frames back and can take a peek at them.

While I image from DSNM, I am also a part of Sierra Remote Observatories in San Jose, California, and Star Shadows Remote Observatory in Chile. You can never have too much data, and imaging

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5. These galaxies, NGC 4438 and NGC 4435, are nicknamed The Eyes. This is an LGRB image with exposures of 8, 4, 4, and 4 hours, respectively.

6. The Crescent Nebula (NGC 6888) is a popular astroimaging target. To make this photo unique, Mark went as deep as possible with the Oxygen-III filter, using a series of one-hour exposures with a 14.5-inch RCOS f/8 telescope and Apogee Alta U16M camera running at –31 degrees Fahrenheit (–35 degrees Celsius). The final Hα/OIII/RGB image has exposures of 6, 10, 4.25, 2.75, and 3.5 hours, respectively.

7. A seldom-imaged area in Orion, this region features a beautiful full field of wispy blues and dynamic reds. The LGRB image contains exposures of 3.75, 2.5, 2.5, and 2.5 hours, respectively.

8. NGC 4725 is a spiral galaxy much like our Milky Way. Mark captured this image, which has been inverted for added contrast, using Stellar Winds Observatory’s 24-inch PlaneWave CDK24. He used an SBIG STX 16803 camera with an SBIG AOx adaptive optics unit and an Astrodon filter wheel. This LGRB image has exposures of 5.75, 3.25, 3.25, and 3.5 hours, respectively.

9. The western part of the Veil Nebula is often called the Witch’s Broom (NGC 6960). Mark worked on this particular image, taken with an SBIG STX 16803 camera and a PlaneWave 17-inch f/6.7 on a PlaneWave Ascension 200HR German Equatorial Mount, for several months. He notes that it was quite a challenge to produce, as the bright magnitude 4.2 star fell very close to the edge of the frames. The Hα/OIII/LRGB image has exposures of 7.5, 9, 3, 3, 3, and 3 hours, respectively, for each panel of the mosaic.

10. NGC 1275 (also known as Perseus A or Caldwell 24), visible at center, houses an actively feeding central supermassive black hole. This shot of the active galaxy was taken with a PlaneWave 24-inch f/6.7 telescope on a PlaneWave Ascension 200HR German Equatorial Mount, using an SBIG STX 16803 camera. It is an LGRB image with exposures of 8.3, 3.25, 3.25, and 3.25 hours, respectively.

Amateur astronomers can definitely contribute to science.

After all, you never know what will end up in your images.

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new targets from the Southern Hemisphere has been fascinating.

I’ve embraced the constant change and growth in this field and try to keep cur-rent with videos, books, online informa-tion, and trial and error. My current programs of choice for processing are CCDStack, Photoshop, and, more recently, PixInsight. For many years, I’ve used CCDStack to do my image calibration. For research purposes, the images are com-plete at this point, but for me this is just the beginning. Adding my own creative take on the final product is what I love the most, and I can spend tens of hours

working on one image to get it just right. My goal is to keep the images as real as possible, while adding my own artistic influence along the way.

Coming full circleOne spring day last year, I received a package in the mail from a class of fourth-graders at a local elementary school. Each student had picked an object from my website (www.hansonastronomy.com) and had written a poem and drawn a pic-ture about the object. My heart melted. These kids were looking at my pictures! How many of them were curious and had

questions they wanted answered? Would one of them grow up to be an amateur astronomer, scientist, or astrophotogra-pher? Would I play the “Doc” role to one of these curious kids in the future? What will their contributions reveal that they never imagined? I recalled my time in Ms. Z.’s space science class. Hopefully, this is my way of knowing that my Astronomy magazine loans have been forgiven.

Mark Hanson, who has been an amateur

astrophotographer for about 25 years, regularly

contributes to Astronomy and works as a

part-time installer for PlaneWave Instruments.

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11. This two-panel mosaic shows the well-known Whirlpool Galaxy (M51a or NGC 5194) and its companion (M51b or NGC 5195) at the top, with the rarely imaged NGC 5198 south of the pair. Mark took this photo using a PlaneWave 17-inch f/6.7 on a PlaneWave Ascension 200HR German Equatorial Mount, with an SBIG STX 16803 camera. The Hα/LRGB image has exposures of 7, 16.7, 5, 5, and 5 hours, respectively, for M51, and LRGB exposures of 7.5, 4, 4, and 4 hours, respectively, for NGC 5198.

12. This exceptionally deep color view of the Cocoon Nebula (IC 5146) traces tantalizing features within and surrounding the dusty stellar nursery. It was taken with a 20-inch Officina Stellare Pro RC telescope on a Paramount ME II Mount.

13. NGC 2023 in Orion is an emission and reflection nebula. In this image, Mark and his colleagues bring it out of “the shadow of the Horsehead” using an FLI 16803 camera on a 16-inch RCOS telescope and PlaneWave Ascension 200HR German Equatorial Mount.

14. Spiral galaxy NGC 4151 in Canes Venatici hosts one of the brightest active galactic nuclei known at X-ray wavelengths. The small spiral galaxy visible to the bottom right of NGC 4151 is NGC 4156. Mark captured them with a PlaneWave 24-inch f/6.7 telescope on a PlaneWave Ascension 200HR German Equatorial Mount, using an SBIG STX 16803 camera. His LGRB image has exposures of 7.5, 4, 4, and 4 hours, respectively.

15. Near the Crescent Nebula lies PN G75.5+1.7, also called the Soap Bubble Nebula. Mark captured it with a PlaneWave 24-inch f/6.7 telescope, using an SBIG 16803 camera. This Hα/OIII/LRGB image contains exposures of 10.5, 12, 3.5, 3.5, 3.5, and 3.5 hours, respectively.

16. As one of the more dynamic and colorful areas in the southern sky, this beautiful star-forming region in the constellation Corona Australis has much to offer. This image was taken using an FLI 16803 camera on a 16-inch RCOS telescope with a PlaneWave Ascension 200HR German Equatorial Mount. It is an LGRB image with exposures of 21, 14.5, 13.5, and 13.5 hours, respectively.

17. NGC 3718 is an interesting galaxy with a warped structure; NGC 3729 is the smaller spiral galaxy in this image, showing remarkable detail as well. Mark shot the pair over two nights with excellent transparency and seeing, using a 14.5-inch RCOS f/8 telescope and an Apogee Alta U16M camera running at –31 F (–35 C). He spent several weeks processing this deep LGRB image, which contains exposures of 8, 4.3, 3.3, and 4.3 hours, respectively.

18. IC 10 is a starburst galaxy within the northern constellation Cassiopeia. Mark took this image using a 20-inch Officina Stellare Pro RC telescope and an Apogee Alta U16M camera.

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IC 4812

HS 176270

Bernes 157

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HD 176386

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NGC 6729

T Coronae Australis

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Do you like to take images of large star fields or pictures of extended nebulous objects using an astronomical CCD, cooled CMOS, or DSLR camera? If the

answer is yes, you’ll want to take a hard look at Meade’s new 70mm Astrograph Quadruplet APO Refractor. Sporting well-corrected optics, a smooth 2.5" focuser, and a 42-millimeter corrected image circle, this scope can handle cameras with full-frame chips. It’s also lightweight, so it rides easily on just about any mount.

When I take wide-field shots, I enjoy the simplicity of unguided imaging that short-focal-length instruments allow. So, I jumped at the opportunity to put this scope through its paces in my backyard observatory.

UnpackingThe scope arrived in a nice aluminum carrying case packed in cutout foam. It included attached rings with a short, blue-anodized Vixen-style dovetail plate bolted to them. Also mounted to the tube was an adapter for a red-dot finder or other pointing device.

The scope is quite light, weighing in at just 4.5 pounds (2 kilograms). It has a white finish and comes with a sliding dew

shield with a light-blue-anodized push-on lens cover. The 2.5" focuser features a standard coarse-focus knob on one side and a 10-to-1 blue-anodized fine-focus knob on the other. The range of the focuser is 30 mm with an engraved scale on top. Racking it in and out felt buttery smooth.

The back end of the drawtube includes a screw-on cover and terminates with a 48-mm rotatable threaded opening, which is also smooth. Meade doesn’t include a star diagonal because the scope is an astro-graph and not a visual instrument.

Optically, the 70mm Astrograph is a Petzval design with a doublet lens up front and two more corrective elements farther back within the tube assembly. Each of the four elements is made from extra-low-dispersion glass, and all are fully multicoated.

MountingWhen I tried to mount the scope on my Paramount MyT, I noticed a problem. I wanted to use a Losmandy-style dovetail plate and slide it onto my mount’s plate. However, that wasn’t possible because of the low-profile rings. There was barely any room between the bottom of the scope and dovetail plate, so it was impossible to attach a camera. The camera would hit

the dovetail plate, and there was no way to move the scope forward to balance.

The only solution would be to attach a set of risers to the rings. These would raise the scope enough to allow me to attach a camera. I didn’t have any risers that would fit the rings, so I mounted a different scope on the MyT and bolted the Meade to a short dovetail plate that rode on top of the other scope’s rings. This provided me with enough room to attach the camera to the scope and still slide it forward or backward to balance the setup.

The critical focus zone of an f/5 tele-scope like this one is tiny, on the order of 22 micrometers through a green filter, so I also wanted to hook up a motorized focuser to achieve best focus using automa-tion. Luckily I had one designed for 2.5" and 3" focusers. I easily adapted it to the Meade focuser, mounting it on the fine-focuser knob’s side. I used a few shims to allow the unit to tighten around the plan-etary gear housing, and it fit nicely.

Under the starsWith the scope mounted, the first camera I decided to use was the SBIG STL-11000. I wanted to see how the scope handled a full-frame chip and to see if the focuser would handle the weight of this large

Meade’s 70mm Astrograph Quadruplet APO Refractor is for astroimaging only. The optics sport a four-element Petzval design with a focal ratio of f/5. IMAGE COURTESY OF MEADE


camera. This camera’s detector is a stan-dard 36x24 mm chip with 9-micrometer pixels. It provided an image scale of 5.35" per pixel, which yielded a huge field of view of 6° by 4°.

This setup can take in sweeping views of large objects. The scope’s advertised image circle is 42 mm, and the full-frame camera worked well with it. Once in focus, I used CCD Inspector to measure the col-limation and curvature.

Collimation was spot on (within 1 pixel). Curvature measured 10 to 11 percent, a quite respectable number. My flat-field analysis shows light loss to be 8 to 9 percent in one corner and less in others. This means vignetting is minimal and probably due to a bit of tilt in the system with the large chip.

When I zoomed in to a full-size image, I noticed that the stars in the extreme corners of the chip were not perfectly round but slightly elongated. It wasn’t objectionable, however. Being right at the edge of the image circle, the optics did a decent job of providing good correction out to the edge of the field.

Also, as far as I could tell, the focuser did a good job holding this nearly 5-pound camera without sagging. With an adapter and a spacer on the camera, it threaded right onto the rear of the focuser. The camera-scope combination came to focus about 15 mm out from the fully racked-in point. The camera was easy to rotate to any desired angle. Because the focuser held this large camera well, it will have no issue holding other CCD cameras and DSLRs.

I also tested the scope with my QSI 583 camera, which uses an APS-C Kodak 8300 chip with a diameter of 22.5 mm and 5.4-micrometer pixels. This camera resulted in a image scale of 3.21" per pixel and a large field of view of 3° by 2°. With just the adapter threaded into the camera, this setup came to focus about 9 mm out.

The first test images showed excellent cor-rection all the way into the corners.

Curvature measured again around 10 to 11 percent, and a flat-field analysis showed light loss in the corners to be only around 4 percent. I saw no vignetting. With either camera, the focal length measured out at 349 mm, which is right on the money with the advertised 350 mm focal length.

From these initial tests, I concluded that excellent images are possible with either a full-frame or APS-C camera.

ImagingAfter waiting a week for the weather to improve (including a near miss by a tropi-cal storm), I finally got some clear nights to put the scope through its paces. With the SBIG camera, I targeted the globular cluster M53 and its companion NGC 5053. With the QSI camera, I imaged the globu-lar cluster M5 and later at night the region of the Lagoon and Trifid nebulae (M8 and M20) in Sagittarius.

The extremely wide field afforded by the latter instrument allowed me to cover a huge portion of the sky. This scope’s fast (f/5) focal ratio made acquiring the data quick. After processing the images, I was happy to see that there were no optical issues whatsoever.

Final thoughtsThe 70mm Astrograph Quadruplet APO Refractor is an excellent scope for imag-ing. The optics are tack-sharp, and I didn’t notice any chromatic aberration, telling me that the lens elements are matched well. The scope produces little vignetting using 48 mm adapters. Its ability to bring all the colors to focus at nearly the same point was excellent.

Meade’s focuser is also well made and smooth. I had no issues with sagging, even when I used a heavy camera. It comes with a manual rotator, which makes it easy to set your camera to any angle. The focuser also can accept focus motors from several different suppliers.

The rings supplied with the scope could use some help. You’ll need risers to be able to set up the scope with a camera on a Losmandy-style dovetail plate. If you use it on a mount with a Vixen-style plate, you may be able to use your camera without risers. In either case, risers will definitely come in handy. When I tightened the rings, the two halves bottomed out, so I wasn’t sure if the scope was secure within them. Using a bit of tape as a shim will help tighten the ring connection.

All in all, Meade’s Astrograph is an extremely capable and well-corrected telescope that should let you capture some spectacular wide-field images.

Meade 70mm Astrograph Quadruplet APO RefractorOptical design: Petzval system

Focal length: 350 millimeters

Focal ratio: f/5

Focuser: 2.5" two-speed rack-and-pinion

Dimensions: 12¼" by 4½" by 5½" (311 by

114 by 140 millimeters)

Weight: 4.5 pounds (2 kilograms)

Includes: Aluminum carry case

Price: $1,199

Contact: Meade Instruments

27 Hubble

Irvine, CA 92618

949.451.1450

www.meade.com

PRODUCT INFORMATION

Jonathan Talbot is a longtime imager and

equipment tester who lives in Ocean Springs,

Mississippi.

The author attached his QSI 583 camera to the Meade and combined 96 minutes of exposures through R, G, and B filters to create this wide-field image of the Lagoon and Trifid nebulae (M8 and M20). JONATHAN TALBOT

The author captured this image of globular clusters M53 and its fainter companion NGC 5053. He used an SBIG STL-11000 CCD camera and captured RGB exposures totaling 80, 80, and 65 minutes. JONATHAN TALBOT


Astroimaging coursePixInsight Instructional Videos and TutorialsTucson, ArizonaAstronomy Contributing Editor

Adam Block offers a series of

video courses on PixInsight. He

has created more than 33 hours

of in-depth instruction, and he’s

adding more. Block will help you

create beautiful images of the

universe through technical profi-

ciency and thoughtful artistry.

$180–$250www.AdamBlockStudios.com

12-inch scopeOmegonLandsberg, GermanyOmegon’s Ritchey-Chrétien Pro

RC 304/2432 Truss OTA is an

optical tube assembly made of

carbon fiber. The mirrors are

hyperbolic and made of quartz,

a material that has virtually no

thermal expansion. The tube is

33.7 inches (855 mm) long and

weighs 53 pounds (24 kilograms).

$3,690+44 203 8688042www.omegon.eu

Solar scopeOrion Telescopes & BinocularsWatsonville, CaliforniaOrion’s 70mm White-Light Solar

Refractor Telescope features a

built-in solar filter, 2.75 inches of

aperture, and a 500-millimeter

focal length. The included

20mm and 10mm 1¼" eyepieces

provide magnifications of 25x

and 50x, respectively. Orion

includes a 1¼" star diagonal.

$149.99800.447.1001www.telescope.com

Eclipse mapGreat American EclipseSanta Fe, New MexicoThis map of the total solar

eclipse on July 2, 2019, over

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important details and times,

and even mountain shadows

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The map, printed on glossy

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11 by 17 inches (28 by 43 centi-

meters) and is shipped in a

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NEWPRODUCTS

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Attention, manufacturers: To submit a product for this page, email [email protected].

Lite OWL 3-D Viewer

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Made by the London Stereoscopic Company, the Lite OWL can be

used to view stereo cards (both modern and vintage) and stereoscopic

photos and illustrations in books or magazines. You can also use

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Also Available: OWL 3-D Stereo Cards Astro Series 1 & 2


he Moon, the

brightest object in

the night sky, has a

naked-eye secret: its

limb. The illumi-

nated edge of the Moon’s vis-

ible surface has a remarkable

nature that’s easy to overlook.

What you experience, however,

depends on how carefully you

examine it.

Note: When I write, “illumi-

nated edge,” I’m not talking

about the bright side of the

terminator (the line dividing

day and night, where shadows

highlight the view). I’m refer-

ring to the rounded bright edge

of the Moon that’s not the ter-

minator. At Full Moon, the

illuminated edge goes all the

way around.

Padraig Houlahan of

Flagstaff, Arizona, recently

noticed one peculiarity:

“Regularly when I look at the

Full Moon, I see an effect that

I have not seen documented

anywhere, and I was wonder-

ing if you knew of it.”

Namely, Houlahan noticed

that the edge of the Full Moon

appears “disproportionately

washed out,” meaning it looks

“featureless and brighter” than

the rest of the disk. Houlahan

doubted the phenomenon is

due to contrast effects alone

— and he’s right.

It’s a wonderHoulahan’s observation of

lunar limb brightening is

worthy of praise because little

naked-eye attention is given

to it during each lunar month,

and some books on the Moon

overlook it altogether. On top

of all that, what one sees along

the limb is not consistent.

If the Moon were a uniform

(smooth) sphere, its edge would

reflect no sunlight toward

Earth, making the limb appear

dark to us. But the Moon has

great surface irregularities —

rocks, mountains, and other

topographical features — that

effectively scatter sunlight

toward our eyes at optical

wavelengths. (The lunar limb is

dark at radio wavelengths.)

Speaking generally, then, we

say that during the waxing and

waning phases, the Moon’s

circular edge has a bright limb

facing the Sun and a dark limb

shadowed from it.

A casual glance at the illu-

minated edge will show it

brighter than areas closer to

the Moon’s terminator. But if

you take time to study the

limb — running your gaze

along the edge and making

SECRETSKY

Lunar limb magic Explore often-overlooked features of the Moon’s edge.

mental notes — you will see

that the limb is irregularly

bright with darker segments.

What you see at any given

time depends on many factors,

including phase angle effects,

variations in the scattering of

sunlight, and lunar librations

— slight axial nods (in latitude)

and swivels (in longitude) that

swing features gently in and

out of view along the Moon’s

limb as our neighbor in space

orbits Earth.

It’s best to look for the limb

effects in twilight, when the

contrast between the Moon’s

edge and the sky is lowest. I

suggest starting with a young

waxing crescent because there

often are great variations along

that slender arc of illumination.

First compare the general

appearance of the limb to fea-

tures closer to the terminator.

Then go in for the detailed

study using direct vision.

Use the extra magnification

of binoculars if you need to

confirm any uncertain naked-

eye views. Sketch and record

what you see each night, and

compare these views during

another lunation, when the

librations are different.

Lunar highlands will create

the brightest effects, but even

these regions vary in surface

irregularities and extent. Look

also for contrast effects within

the highlands, especially

between craters of high reflec-

tivity (caused by blankets of

ejecta surrounding them) near

the limb.

And, as always, let me know

what you see or don’t see at

[email protected].

B Y S T E P H E N J A M E S O ’ M E A R A

T

BROWSE THE “SECRET SKY” ARCHIVE AT www.Astronomy.com/OMeara.

The lunar limb is bright, but with a watchful eye, a skilled observer can make out subtle (and not so subtle) differences in its intensity. BOTH IMAGES: STEPHEN JAMES O’MEARA

Darkening the image to the left using software like Photoshop reveals the lunar limb’s intensity variations more clearly.

Stephen James O’Meara is a globe-trotting observer

who is always looking for the next great celestial event.

It’s best to look for the limb effects in twilight, when the contrast between the Moon’s edge

and the sky is lowest.


Journey from Peru’s Sacred Valley of the Incas to the ancient mountaintop city of

Machu Picchu — and enjoy an unforgettable view of the July 2 total solar eclipse!

Join us for a once-in-a-lifetime South American odyssey with a dramatic focal point: a total solar eclipse.

Our itinerary weaves together two dimensions of this fascinating continent: spectacular landscapes with

unmatched views in remote areas of Chile and Peru; and a legacy of engineering, architecture, art, and

philosophy that includes a tradition of astronomical observation dating back two millennia.

RESERVE YOUR SPOT TODAY! Astronomy.com/magazine/trips-tours/2019-chile-northbound

TOTAL SOLAR ECLIPSE: Ancient Paths to the Present

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TRIANGULUM

ARIES

ANDROMEDA

M33

7 Trianguli

15Trianguli

14 Trianguli

R Trianguli

5°


s an avid angler, I

prefer small ponds

over large lakes and

reservoirs. Fishing

a large body of

water can be a daunting task.

With hundreds of acres to

explore, I could never cover all

the hot spots in a day’s time. A

5- to 10-acre pond, on the other

hand, can be easily covered in a

matter of hours.

It’s the same situation when I

switch from fishing to observ-

ing. I prefer to “paddle around”

a small constellation like

Delphinus or Lyra, rather than

ride the high seas in a vast stellar

aggregation like Virgo or

Ophiuchus. With that in mind,

let me invite you to one of the

night sky’s smallest “ponds,”

Triangulum, whose 132-square-

degree area is one-tenth that of

the largest constellation, Hydra.

If you’re not sure of

Triangulum’s location in the

night sky, refer to the StarDome

map in the center of this maga-

zine. From mid-northern lati-

tudes, Triangulum appears high

in the December evening sky

between Aries and Andromeda.

Punctuated by three stars

arranged in the form of a long,

narrow triangle, this constella-

tion is aptly named. It is made

up of Alpha (α) at magnitude

3.4, Beta (β) at magnitude 3.0,

and Gamma (γ), which shines at

magnitude 4.0. Gamma is

attended by the 5th-magnitude

stars Delta (δ) and 7 Trianguli.

This optical triplet can be

glimpsed with the naked eye

under a dark sky, and it is an

OBSERVINGBASICS B Y G L E N N C H A P L E

Treasures in Triangulum The Triangle constellation may be small, but it’s packed with a wealth of worthwhile targets.

Iota (ι) Trianguli — also

known by the Flamsteed desig-

nation 6 Trianguli and the

Struve double star designation

Struve 227 (STF 227 or Σ227)

— is a neat double star whose

magnitude 5.3 and 6.7 compo-

nents are separated by 3.7". One

of the 110 entries on my Double

Star Marathon list, it’s rapidly

disappearing in the west during

the March/April time slot when

the Marathon is being con-

ducted. Catch it now while it’s

more conveniently placed. I

recommend a magnification of

at least 75x for a clean split.

While Iota is still in the eye-

piece field, look about a half-

degree eastward. You should

spot a stellar pair that only a

seasoned double star observer

can see. This is Struve 232 (STF

232 or Σ232), a near-twin sys-

tem (magnitudes 7.8 and 7.9)

with a 6.5" separation. How

unfortunate that hundreds of

eye-pleasing pairs like this go

unobserved because of their

relative faintness. A bright

showpiece double like Albireo

(Beta Cygni) has the in-the-

face visual impact of a snow-

capped mountain peak; STF

232 possesses the delicate

beauty of a single snowflake.

Triangulum’s key center of

attraction is the Pinwheel

Galaxy (M33). Notorious for its

elusiveness, M33 spreads the

light of a 6th-magnitude star

over an oval-shaped area that

exceeds that of a gibbous Moon.

Surprisingly, M33 is faintly vis-

ible with the unaided eye and

relatively easy to spot through

binoculars, provided you view it

from an area free of light pollu-

tion and atmospheric haze. The

problem occurs if you try to

view M33 with a telescope and

high-power eyepiece. Instead,

work with a telescope and eye-

piece combination that pro-

duces a field of view 2° or more

across. My best view of M33

came with a 4-inch rich-field

scope and magnification of 30x.

Does my penchant for small

constellations mean that I avoid

the large ones? Hardly! In a few

months, I’ll take you to Hydra

to demonstrate how to break

down an expansive constella-

tion the way an angler dissects

a large body of water.

Questions, comments, or

suggestions? Email me at

[email protected]. Next

month: It’s a bird! It’s a plane!

It’s Super Moon! Clear skies!

eye-catching sight through 7x

binoculars or finder scopes.

Some 15° east of Delta is

another triangle formed by the

5th-magnitude stars 14 and 15

Trianguli and 6th-magnitude

HD 15755 (shown in orange).

Their spectral classes are K5,

M4, and G5, respectively, so

you’ll want to compare their

colors through binoculars or a

telescope. 15 Trianguli is a dou-

ble star with a wide separation

of 142". Its companion is a mag-

nitude 6.8 A-type star, produc-

ing a striking color contrast.

Slightly east and 0.5° south of

15 Trianguli is the long-period

variable R Trianguli. Over an

average of nine months, this

pulsating red giant’s magnitude

ranges from a maximum of 5.5

to a minimum of 12.5 and back.

According to “Bulletin #81” of

the American Association of

Variable Star Observers

(AAVSO), R Trianguli is cur-

rently brightening to an early

February maximum.

If you’ve never watched a star

undergo a dramatic change in

brightness, give R Trianguli a

look-see once a week. You can

create your own chart showing

R Trianguli and the magnitudes

of nearby comparison stars

by logging on to the AAVSO

website (aavso.org), or you

can email me for a chart that

I’ve put together.

A

BROWSE THE “OBSERVING BASICS” ARCHIVE AT www.Astronomy.com/Chaple.

Triangulum is one of the smallest constellations in the night sky. But despite its modest size, it affords informed observers many rewarding sights. ASTRONOMY: ROEN KELLY

Glenn Chaple has been an avid observer since a friend

showed him Saturn through a small backyard scope in 1963.

Let me invite you to one of the night sky’s smallest “ponds,” Triangulum.

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Cassiopeia the Queen

is one of the most

distinctive constel-

lations in the sky. Its

five brightest stars

form a W pattern that is easily

recognizable by even the most

casual stargazer.

In Greek mythology,

Cassiopeia was the wife of King

Cepheus, monarch in ancient

Ethiopia. Nearby in our sky is

their only child, Princess

Andromeda, whom we visited

in my last column. Cassiopeia

was banished to the sky after

boasting that Andromeda was

more beautiful than the

Nereids, the female water spir-

its who accompanied Poseidon,

Greek god of the seas.

Cassiopeia forever wheels

around the North Celestial Pole

sitting on her throne, spending

half of her time clinging to it to

keep from falling off.

For most of us, Cassiopeia is

a circumpolar constellation,

and so it graces our skies at

all hours all year long. But

this time of year, she appears

highest in the evening sky.

November is an ideal time to

marvel at the many wonderful

binocular targets that lie

within. There are too many to

visit in a single column, but

here are a few of my favorites.

Let’s begin by centering

on Delta (δ) and Epsilon (ε)

Cassiopeiae in the constellation’s

W. Since these 3rd-magnitude

stars are separated by just

under 5°, they should squeeze

into the same field through

most binoculars.

Just 1° northeast of Delta, we

find open cluster M103, the

final entry in Messier’s catalog

when it was published in 1781

in the Connaissance des temps

for 1784. M104 through M109

were added by 20th-century

astronomical historians after

examining Messier’s unpub-

lished notes.

Messier did not discover

M103, however. Like many ear-

lier entries in the catalog, his

contemporary, Pierre Méchain,

first uncovered it. In this case,

he bumped into it just before

Messier’s catalog was published.

Messier actually never saw it

before his catalog went to press.

Had he the opportunity,

Messier would have seen a spar-

kling collection of stardust set

in an arrowhead pattern mea-

suring about 6' across. Marking

the tip of the arrowhead is the

pretty telescopic multiple star

Struve 131. Most studies con-

clude, however, that the star’s

association with the cluster is

just a chance line-of-sight

alignment. M103 is estimated to

be 8,500 light-years away, more

than four times farther than

Struve 131. Through giant bin-

oculars and telescopes, those

stars look like blue-white sap-

phires surrounding a lone red

stellar ruby near the middle.

If Méchain and Messier had

more time, they undoubtedly

also would have found our next

target. Can you spy another

faint fuzz 2° northeast of M103?

That’s NGC 663, a striking

assembly of about 80 faint stars.

Those stars shine collectively

at 7th magnitude, but remain

unresolvable individually

through 7x to 10x binoculars.

The brightest just peek out

from the glow in my 16x70s.

Even larger binoculars reveal

that the stars appear bunched

into two asymmetric clumps.

NGC 663 actually stands out

better than M103 through bin-

oculars, so be careful not to

confuse one for the other.

Our last stop this month is

NGC 457, set about 2° southwest

of Delta. More than 80 stars call

this cluster home, with many

visible through steadily braced

10x binoculars if you look care-

fully. Viewing through 70mm

and larger binoculars will reveal

that the stars in NGC 457 create

a distinctive pattern. Some

observers imagine a dragonfly;

others a Hopi kachina doll; or

even Hollywood’s E.T., the

Extraterrestrial. I prefer its com-

mon nickname, the Owl Cluster.

The owl’s body is drawn from

about a dozen stars that shine

between magnitudes 9 and 11,

with two 10th-magnitude suns

marking the tail feathers. Two

arcs, each containing about half

a dozen suns, form the wings.

The east wing is highlighted by

a distinctive 8th-magnitude

orange star, the brightest mem-

ber of the cluster. The owl’s

dazzling “eyes,” marked by

5th-magnitude Phi1 (ϕ1) and

7th-magnitude Phi2 (ϕ2), are

attention-getters. But don’t

be fooled. Both are probably

foreground stars. NGC 457 is

estimated to be about 7,900

light-years away, while Phi1 may

lie anywhere from 2,300 to

4,500 light-years away. While

that’s a high potential error, it

still puts them between us and

the cluster. Probably. Still other

data suggest that they could

actually be at the same distance

as the cluster.

Of Cassiopeia, author

Garrett Serviss wrote in his

1888 book Astronomy with an

Opera-Glass, “Here the Milky

Way is so rich that the observer

hardly needs any guidance.”

This still rings true 130 years

later. These three clusters are

just the beginning. By sweeping

the Cassiopeia “W” with your

binoculars, you’ll find treasures

in nearly every field.

Until we meet again next

month, as autumn fades into

winter, remember that when it

comes to stargazing, two eyes

are better than one.

Sighting the Queen

Cassiopeia offers sparkling binocular treasures.

The Owl Cluster, NGC 457, is a bright star group shaped in a birdlike form. It features the bright foreground stars Phi1 and Phi2 Cassiopeiae.

The rich open cluster M103 appears as a striking arrowhead-shaped cluster of glistening stars. ANTHONY AYIOMAMITIS

Some 80 faint stars make up NGC 663, a cluster that stands out well from the Milky Way as seen in binoculars.

Phil Harrington is a longtime contributor to Astronomy and

the author of many books.

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for nine days of incredible stargazing and breathtaking

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• Enjoy the expanse of stars over the Sonoran Desert during specially

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8


A: When a massive star runs

out of nuclear fuel at the end of

its life, it collapses — the star’s

dense core falls in on itself,

squeezing protons and elec-

trons together to make the

neutrons that form an ultra-

dense neutron star remnant.

The implosion is arrested

when the core reaches the

extreme density of nuclear

matter (i.e., the density found

inside an atom’s nucleus). A

violent rebound follows, eject-

ing matter outward in a super-

nova explosion, which, for

a short while, can shine as

brightly in photons (light)

as an entire galaxy.

The explosion drama starts

in the murky midst of the stel-

lar envelope surrounding the

core. It can take some time

Astronomy’s experts from around the globe answer your cosmic questions.

SUPERNOVA SIGNALS

through matter like phantoms

through walls, they can escape

the star within a few tens of

seconds. On Earth, we can

capture a burst of them (which

is only a tiny fraction of the

total produced) in huge under-

ground neutrino detectors,

before the supernova’s light

shows up.

You can sign up with the

Supernova Early Warning

System network (https://snews.

bnl.gov) to get an alert when

this happens from the neutrino

detector network.

Kate Scholberg

Professor of Physics, Duke University,

Durham, North Carolina

ASKASTR0

Q: IN A SUPERNOVA, WHY DO WE DETECT NEUTRINOS BEFORE LIGHT?

Charles Johnson, Lake Geneva, Wisconsin

— hours or even a good frac-

tion of a day — for a shock

wave to burst out of the dead

star’s corpse and start the

shining of the supernova. Long

before the visible fireworks,

nearly all the energy of the

star’s inward tumble has

already escaped, in the form of

nearly invisible neutrinos.

Neutrinos are elementary

particles that are famously

“ghostly” — they only rarely

bump into matter, so they’re

difficult to detect. On average,

a neutrino will travel through

a light-year of matter before

colliding with an atom! In the

ferociously hot and dense mat-

ter at the heart of the star’s

collapse, neutrinos are pro-

duced in huge quantities.

Because neutrinos just slip

Q: WHAT’S THE DIAMETER

OF THE LARGEST

EXOPLANET FOUND SO FAR?

Terrence Gollata

Manitowoc, Wisconsin

A: The largest planet discov-

ered to date, that astronomers

are sure is a planet and has an

accurately measured diameter,

is HAT-P-67 b. This planet is a

“hot Jupiter” — a gas giant

similar to Jupiter or Saturn, but

orbiting so close to its star that

it takes only a few days (4.8

days in this case) for the planet

to orbit once around its sun.

HAT-P-67 b is 2.08 times

the diameter of Jupiter (which

has an average diameter of

about 88,850 miles [143,000

kilometers]), but HAT-P-67 b is

less than 60 percent of Jupiter’s

mass. This makes it the least

dense planet discovered so far.

The large diameter is likely due

to the planet’s proximity to its

star. Gas giant planets like

HAT-P-67 b experience

extreme levels of radiation.

High-energy X-rays and ultra-

violet light from the star ionize

the outer gaseous atmosphere

of the planet, stripping it of

electrons and causing it to heat

up and expand. The heated

outer atmosphere also begins

to escape. This hot, escaping

gas is called the exoatmosphere.

HAT-P-67 b was discovered

in 2017, so measurements of

the hot, ionized exoatmosphere The widest known exoplanet, HAT-P-67 b, is a gas giant spanning twice the diameter of Jupiter, but it orbits so closely to its star that its year lasts less than five Earth days. KEVIN GILL

Cassiopeia A (left) is the remnant of a star whose supernova light reached Earth about 300 years ago. Today, huge detectors, such as the one at the Daya Bay Reactor Neutrino Experiment (right), can capture a small fraction of the neutrinos produced by supernovae. NASA/JPL-CALTECH; ROY KALTSCHMIDT, LBNL


have not yet been attempted.

However, the size of the exoat-

mosphere of other hot Jupiter

planets like HD 209458 b (the

first transiting planet ever dis-

covered) can be 10 times larger

than the already inflated atmo-

sphere. HAT-P-67 b’s star is

evolving into a red giant, so it

is brighter than it was in the

past. Its increasing radiation

will cause more heating and

more expansion of the planet’s

atmosphere in the future.

Leslie Hebb

Assistant Professor, Department of

Physics, Hobart and William Smith

Colleges, Geneva, New York

Q: HOW FAR FROM EARTH

WOULD A SPACE CAMERA

HAVE TO BE TO OBTAIN A

FULL IMAGE OF OUR OWN

MILKY WAY GALAXY?

Alan B. Thomas

Warrington, England

A: The specific answer to this

question depends on the type

of camera you’re talking about.

Objects appear smaller with

greater distance, so a camera

with a smaller field of view

(that can image less of the

space in front of it in one shot)

must be farther from an object

than a camera with a large

field of view to take an image.

So, let’s assume a few things:

First, let’s consider a camera

like JunoCam on the Juno

orbiter currently circling

Jupiter. JunoCam has a pretty

large field of view for a space-

craft camera: 58° across. (For

comparison, a 35mm lens on

a DSLR has a field of view of

63°.) So, to capture the Milky

Way in one shot, JunoCam

would have to be at a distance

such that the entire disk of our

galaxy takes up 58° (or less).

Second, let’s assume the visible

disk of the Milky Way, which

is a spiral galaxy, is 100,000

light-years in diameter; this is

a pretty good estimate, though

it’s continually being refined

based on new, more accurate

measurements. Third, while

we know that the solar system

is nowhere near the center of

our galaxy, and is instead

about 26,000 light-years from

the center, let’s assume we’re

sending JunoCam straight up

from the center of the galaxy,

for simplicity.

Calculating an object’s

angular size — how large it

appears on the sky — is pretty

straightforward for small

angles, but gets a little more

complicated as you approach

larger ones (up to sizes of 180°).

Still, it’s possible, and regard-

less of the formula, the angular

size (here, we’re assuming 58°

to fit in JunoCam’s field of

view) depends on the object’s

physical size (in this case,

100,000 light-years) and the

distance to the object (what we

want to know). It turns out that

a spacecraft carrying JunoCam

would have to be launched to a

position about 90,000 light-

years above the plane of the

Milky Way to be able to look

back down and just barely fit

the entire disk of the galaxy in

its field of view.

Alison Klesman

Associate Editor

Q: DO CONSTELLATIONS

LOOK THE SAME FROM

THE OTHER PLANETS

IN THE SOLAR SYSTEM?

Ronald Hellman

New York, New York

A: When you look at the sky,

you’re seeing a two-dimensional

projection of three-dimensional

space — the stars are spread

out in all directions, including

distance, but we don’t get that

distance information when we

look up (or when we take a

photograph). The constella-

tions are simply specific pat-

terns picked out on the sky;

they don’t take distance into

account. Some stars in a con-

stellation may be close, while

others are not. For example,

Sirius (Alpha [α] Canis

Majoris) is 8.6 light-years away,

but Aludra (Eta [η] CMa) is

about 2,000 light-years distant.

Though these two stars are in

the same constellation and

appear near each other on the

sky, in reality they are thou-

sands of light-years apart.

If you were to travel far

enough away from Earth (we’re

talking light-years), the pat-

terns would certainly start to

change. But because the stars

are so distant compared with

the size of our solar system

(which is just light-hours

across), the projection effect

— the patterns of stars we see

— from Earth holds true on

the other planets circling the

Sun. From any planet in the

solar system, the same constel-

lations we see here on Earth

are visible and recognizable.

The biggest difference you’d

notice is their orientation

in the sky (whether they’re

high or low compared to the

horizon and zenith), which

depends on the orientation of

a planet’s poles, as well as your

location on the planet. Polaris

(Alpha [α] Ursae Minoris) is

the North Star when viewed

from Earth because of the tilt

of its poles, but this is not true

from the other planets.

Alison Klesman

Associate Editor

Send us your questionsSend your astronomy

questions via email to

[email protected],

or write to Ask Astro,

P. O. Box 1612, Waukesha,

WI 53187. Be sure to tell us

your full name and where

you live. Unfortunately, we

cannot answer all questions

submitted.

On March 11, 2004, NASA’s Mars Exploration Rover Spirit snapped an eight-second exposure to test its abilities to study the night sky from the martian surface. A portion of the stars in Orion the Hunter, including the three belt stars and bright Betelgeuse, are visible in their familiar configuration at the bottom and right of the image. NASA/JPL/CORNELL


1. SCOPE UNDER THE STARS

This two-image panorama shows part of the Observatorio del Roque de los Muchachos, which lies 7,875 feet (2,400 meters) above sea level on the island of La Palma in the Spanish Canary Islands. This dome houses the Telescopio Nazionale Galileo, which has a 141-inch (3.58 meters) primary mirror. • Chirag Upreti

2. OUTBURST!

Comet PANSTARRS (C/2017 S3) underwent what astronomers term an outburst (a major brightening) on July 20, 2018. The image on the left shows the comet with a 3°-long tail. Only 23 hours later (right), the comet was a full magnitude fainter, and no hint of the tail could be seen. • Gerald Rhemann

READERGALLERY

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3. GALACTIC

SPLENDOR

The Antlia Cluster (Abell S0636), which contains more than 230 galaxies, lies 135 million light-years away, making it the third-nearest galaxy cluster. This group is part of the Hydra-Centaurus Supercluster. The reddish nebula at left, plus all the single stars, belong to our galaxy. • Kfir Simon

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Send your images to: Astronomy Reader Gallery, P. O. Box

1612, Waukesha, WI 53187. Please

include the date and location of the

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exposures. Submit images by email

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4. ONE RING

Astronomy columnist Glenn Chaple discovered Chaple’s Arc in the mid-1970s while looking for the double star HJ 1470 in Cygnus. Also known as the Cygnus Fairy Ring, this ring of suns has a diameter of 22'. • Derek Santiago

5. RISING SUN

The Sun is hidden by a cloud bank, but impressive crepuscular rays still fill the eastern sky July 20, 2018. The Yangtze River flows in the foreground in Shanghai’s Wusong Paotaiwan Wetland Forest Park. • David Xu

6. GATHERING

Mars (the brightest object), Saturn (top), and globular cluster M22 in Sagittarius group together March 31, 2018. Close inspection of the image reveals Titan just below Saturn.• Damian Peach

7. AND IN THE DARKNESS . . .

Dark nebulae Barnard 8, B9, and B11 are rarely imaged. They lie in the constellation Camelopardalis the Giraffe at the edge of the Milky Way.• Patrick Winkler

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Hunting for cluster pairsHundreds of galaxies populate the northeastern corner of Canes Venatici the Hunting Dogs. These island universes make up the massive galaxy cluster Abell 1758, which lies some 3.2 billion light-years from Earth. About 20 years ago, astronomers learned that this throng consists of two subclusters, separated by 2.4 million light-years yet still bound together by gravity. But more recent observations reveal that the northern subcluster seen in this Hubble Space Telescope image also splits into two segments. Disturbances within these sections suggest that they formed as smaller clusters collided and merged. NASA/ESA/HUBBLE

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SOUTHERNSKY MARTIN GEORGE describes the solar system’s changing landscape

as it appears in Earth’s southern sky.

February 2019: Bright planets at dawnOnly one bright planet manag-

es to grace this month’s early

evening sky. Mars stands out

well, however, because it shines

brightly and occupies a region

of sky devoid of conspicuous

stars. On February 1, the Red

Planet glows at magnitude 0.9

against the backdrop of eastern

Pisces. By month’s end, you can

find the magnitude 1.2 world in

southern Aries.

Mars appears about 20° high

in the northwest as darkness

falls. This relatively low altitude

arises because Southern

Hemisphere observers face a

disadvantage at this time of

year. The ecliptic — the Sun’s

apparent path across our sky

that the planets follow closely

— makes a shallow angle to the

western horizon after sunset.

Thus, Mars’ elongation from

the Sun translates more into

distance along the horizon and

not into altitude above it. From

mid-northern latitudes, Mars

appears twice as high at the

same time.

Unfortunately, the Red

Planet proves disappointing

when viewed through a tele-

scope. Although the dust storm

that enveloped the world at its

peak last year has long since

abated, Mars appears only 6" in

diameter. Its low altitude and

tiny size combine to render

Mars a featureless disk.

Mercury reaches greatest

elongation February 26/27,

when it lies 18° east of the Sun.

But it suffers from the ecliptic’s

low angle as well. The planet

climbs just 3° high a half-hour

after sunset and remains lost in

bright twilight.

No other naked-eye planet

appears until after midnight,

but the wait is well worth it.

Jupiter rises first, poking

above the eastern horizon

around 1 a.m. local time in

mid-February. The giant planet

shines at magnitude –2.0, far

brighter than any of the stars

in its host constellation,

Ophiuchus the Serpent-bearer.

Jupiter moves slowly eastward

relative to this starry backdrop

during February.

This gas giant world makes

a wonderful target for telescope

users on any clear morning. Its

large disk — 35" across the

equator and 2" less through

the poles — features plenty of

atmospheric details. And the

planet’s four bright moons typi-

cally change positions notice-

ably in just a few hours.

Although Jupiter is bright, it

pales in comparison to Venus.

You can judge the two easily

February 1, when Venus lies 9°

east of Jupiter and rises less

than an hour after its neighbor.

Venus then shines at magnitude

–4.3, nearly 10 times brighter

than its neighbor. That same

morning, a beautiful crescent

Moon lies just below Venus.

The planet traverses the breadth

of Sagittarius from west to east

during February and leaves

Jupiter far behind. On the 28th,

36° separate the two worlds.

As Venus heads east, it also

moves away from Earth. For

telescope owners, this means

the inner world shrinks while

its phase waxes. On February 1,

Venus shows a disk 19" across

and 62 percent lit. On the 28th,

the planet spans 16" and the

Sun illuminates 72 percent of

its Earth-facing hemisphere.

As Venus races across

Sagittarius, it meets up with the

slowest of the bright planets:

Saturn. On the mornings of

February 18 and 19, the two

make an attractive pair despite

magnitude 0.6 Saturn shining

nearly 100 times fainter.

The ringed planet appears

fairly high in the predawn

darkness this month because

the ecliptic angles steeply to the

eastern horizon on February

mornings. Spend some time

viewing magnificent Saturn

through your telescope. You’ll

see a globe measuring 15"

across surrounded by a dra-

matic ring system that spans

35" and tilts 24° to our line

of sight.

The starry skyFrom the Southern

Hemisphere, many ancient

constellations appear upside

down. Leo the Lion and Taurus

the Bull bear at least some

resemblance to the creatures

they were named after when

viewed right-side up, but that’s

lost when they are reversed.

Probably the most prominent

example is Orion the Hunter.

He stands on his rather small

head, his shoulders hang below

his knees, and his sword seems

to defy gravity. February eve-

nings provide observers with

an excellent view of Orion’s

topsy-turvy world.

When gazing at Orion, peo-

ple often confine their thoughts

to the area enclosed by the four

bright stars marking his knees

and shoulders. But take a few

minutes and look to the west

for the Hunter’s Shield, held up

to defend against the Bull.

Most of the bright stars in a

given constellation have Greek

letters associated with them.

Johann Bayer introduced this

system in his Uranometria

atlas, published in 1603. In gen-

eral, Alpha marks a constella-

tion’s brightest star, Beta the

next brightest, and so on.

Many exceptions to this sys-

tem exist, however. One of the

oddest is that, in some cases,

more than one star has the

same Greek letter. In Orion, all

six stars in the shield have the

Greek letter Pi (π)!

How can this be? Well,

Bayer sometimes assigned a

single Greek letter to multiple

stars that appeared close

together, such as Omega1 (ω1)

and Omega2 (ω2) Scorpii. But in

Orion’s Shield, the Pi designa-

tion covers a string of stars that

spans nearly 10°. Modern star

charts show each star with a

superscript — Pi1, Pi2, and so

on — running from north to

south. Astronomers added the

numbers after Bayer labeled

them all as Pi.

An even more extreme

example lurks in Orion’s neigh-

boring constellation, Eridanus

the River, which meanders

through much of the southern

sky. In that star group, no fewer

than nine stars go by the name

Tau (τ). They span nearly 20°,

all between –18° and –25° decli-

nation. Take a look at magni-

tude 3.7 Tau4, the brightest in

this collection. It is one of the

reddest naked-eye stars in our

night sky, and is the most

strongly colored of Eridanus’

Tau stars. It makes a fine exam-

ple of the admittedly subtle

variations in star colors.

STARDOME


α

α

β

αα

β

ε

ζ

γ

α

β

γ

β

δ

α

α

γ

β

α

β

β

β

ο

β

α

α

α

α ζ

α

α

β

P E R S E U S

AR

IES

PI

SC

ES

CE

TU

S

ER

ID

AN

US

FO

RN

AX

SC

UL

PT

OR

GRU

S

PH

OE

NIX

TUCANAOCTANS

MUSCA

CRUX

NTAURUS

CARINA

VE

LA

AN

TL

IA

PY

XI

S

LE

PU

S

PUPPIS

APUS

TRIANGULUM AUSTRALE

CIRCINUS

CHAMAELEONHYDRUS

HOROLO

GIUM

RETICULUM

CA

EL

UM

CO

LUM

BA

DORADO PICTOR

VOLANS

MENSA

AU R I G ALY N X

CA

NC

E R

M O N O C E R O S

CA

NI S

MA

JOR

O R I O NTAU

RU

S

G E M I N I

C A N I S M I N O R

M1

M35

M44

M47

M42

M41

NG

C 2

47

7

NGC 4755NGC 104

NG

C 2

53

SGP

SCP

M36 M37

M38

Capella

Algol

Castor

Pollux

Procyon

Alp

ha

rd

Mira

Aldebaran

Pleiades

Betelgeuse

Rigel

Sirius

NGC 3372

NGC 2070LMC

SMC

NGC 2561

Canopus

Achernar

Ma

rsU

ranu

s

S

W

N

MAGNITUDES

Sirius

0.0

1.0

2.0

3.04.05.0

Open cluster

Globular cluster

Diffuse nebula

Planetary nebula

Galaxy

THE ALL-SKY MAP

SHOWS HOW THE

SKY LOOKS AT:

10 P.M. February 1

9 P.M. February 15

8 P.M. February 28

Planets are shown

at midmonth

γ

α

CENT

HY

DR

A

CR

AT

ER

SE

XT

AN

S

CO

RV

US

LE

O

LEO

MIN

OR

M6

5

M6

6

NGC 5139

NGC 5

128

Reg

ulus

M1

04

E

FEBRUARY 2019

Calendar of events 2 The Moon passes 0.6° north of

Saturn, 7h UT

The Moon passes 0.6° north of Pluto, 20h UT

4 New Moon occurs at 21h04m UT

5 The Moon is at apogee (406,555 kilometers from Earth), 9h29m UT

6 Asteroid Herculina is at opposition, 3h UT

The Moon passes 1.1° north of asteroid Vesta, 8h UT

7 The Moon passes 3° south of Neptune, 6h UT

10 The Moon passes 6° south of Mars, 16h UT

The Moon passes 5° south of Uranus, 20h UT

12 First Quarter Moon occurs at 22h26m UT

13 Mars passes 1.1° north of Uranus, 20h UT

18 Venus passes 1.1° north of Saturn, 14h UT

19 The Moon is at perigee (356,761 kilometers from Earth), 9h03m UT

Full Moon occurs at 15h54m UT

26 Last Quarter Moon occurs at 11h28m UT

27 Mercury is at greatest eastern elongation (18°), 1h UT

The Moon passes 2° north of Jupiter, 14h UT

STAR COLORS:

Stars’ true colors

depend on surface

temperature. Hot

stars glow blue; slight-

ly cooler ones, white;

intermediate stars (like

the Sun), yellow; followed

by orange and, ulti mately, red.

Fainter stars can’t excite our eyes’

color receptors, and so appear white

without optical aid.

Illustrations by Astronomy: Roen Kelly

HOW TO USE THIS MAP: This map portrays

the sky as seen near 30° south latitude.

Located inside the border are the four

directions: north, south, east, and

west. To find stars, hold the map

overhead and orient it so a

direction label matches the

direction you’re facing.

The stars above the

map’s horizon now

match what’s

in the sky.

BEGINNERS: WATCH A VIDEO ABOUT HOW TO READ A STAR CHART AT www.Astronomy.com/starchart.

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