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Celestial Motion

Chapter 21, pages 597-606Chapter 22, pages 615-619

Lab starts this week—NS 017

Peer Led Instruction

• Library—Wednesday 6:30 to 8:30 PM• Kristin Mooney—Science Education Major• Add ES104X—CRN 11017

• Can add before Oct. 3 session– Do review questions to see if you think it help– Sit in to see if it is for you

Get your lab manual

• Do Prelab 1 and bring to lab class• Lab starts with activities this week• Make-ups are difficult to accomplish, so be

sure to attend your lab regularly• Must pass lab to pass class

Tycho Brahe

• Detailed observations of movement of planets

http://www.hao.ucar.edu/public/education/sp/images/tycho.html

Tycho Brahe in his

observatory• His careful

observations and records are his most important legacy

http://www.hao.ucar.edu/public/education/sp/images/tycho.3.html

Tycho’s 1572 Nova

observations

http://www.hao.ucar.edu/public/education/sp/images/tycho.1.html

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Tycho’s comet of 1577

http://www.hao.ucar.edu/public/education/sp/images/tycho.2.html

Tycho’smodel of

solar system

• Discounted Copernicus model because he could not discern stellar parallax

• It does exist, he didn’t have tools to see it

http://www.hao.ucar.edu/public/education/sp/images/tycho.4.html

Johannes Kepler

• Tycho’s assistant and successor

• Used Tycho’s data to determine planetary orbits are elliptical

http://en.wikipedia.org/wiki/Image:Johannes_Kepler.jpg

First Law of Planetary Motion

• Orbit of planet is ellipse

• Sun at one Focus

Kepler’s 2nd Law

• Equal areas in equal time intervals accounts for the uneven speeds

Kepler’s third law of planetary motion

• p2=d3

p=Period (time to orbit Sun) in Earth yearsd=Distance in Astronomical Units:

1 A.U.=distance from Earth to Sun

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Galileo Galilei• Strong supporter of

Copernican model of planetary movement

• Built 30x telescopes (from descriptions of the devices) and looked at planets and Moon starting in 1609

http://en.wikipedia.org/wiki/Galileo_Galilei#Technology

Galileo’s notes on Jupiter’s moons

• Telescope used to see that another body in solar system is a center of orbital movement

• These moons are not left behind, and Earth’s Moon is not either

Ptolemaic version of Venus Phases of Venus

Galileo’s explanation of Venus’phases Moon’s surface has texture

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Galileo’s Astronomical Discoveries

• When viewed by telescope, planets look like discs, not points of light as stars do

• Jupiter has moons• Venus has phases• Moon’s surface has texture• Sun rotates on an axis

Foucault’s Pendulum

• 1851• Proved Earth does rotate on

its axis—Copernicus’hypothesis

Isaac Newton

• Invented the calculus to simplify calculations

• Explained the orbital motion of planets as the interaction of inertia and gravity

Orbital motion of planets

Brief Review

• Sun is at the center of the solar system• Published by Copernicus

– Supported by Galileo’s telescopic observations of Jupiter and Venus

• Kepler determined orbits are ellipses• Newton determined orbits created by

interaction of inertia and gravity

Constellations

• Star groups• 88 recognized• Stars names by brightness in them

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Orion

• Southern Sky• Hunter• White Tiger

• http://lithops.as.arizona.edu/~jill/EPO/Posters/Orion/protoplanets.html

Star names in Orion

• http://borghetto.astrofili.org/costellazioni/costellazioni.htm

Orion’s place in the sky

• Bright star to lower left of Orion is Sirius

• http://www.windows.ucar.edu/the_universe/images/starmaps/map_orion.jpg

Sirius

• “The Dog Star”• Brightest star in sky• In Canis Major

• http://www.windows.ucar.edu/cgi-bin/tour_def/the_universe/images/starmaps/map_canis_major_jpg_image.html

Arcturus• Second brightest

in northern sky• Very large• Rather cool

• http://www.windows.ucar.edu/cgi-bin/tour_def/the_universe/Arcturus.html

• http://en.wikipedia.org/wiki/Arcturus

Celestial position

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Earth turns pointed at Polaris Polaris and Big Dipper

Polaris and Big Dipper Polaris and Big Dipper

Polaris and Big Dipper—each 8 hours What is a ‘day’?

• Mean Solar Day

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What is a ‘day’?

• Sidereal Day

• Incredibly distant stars—closest is 60,000+ times further than Sun

What is a ‘day’?

• Mean Solar Day—24 hours• Sidereal Day—23 hours, 56 minutes

Plane of the eclipticAnimation of equinox and

solstice

Equinox and solstice related to the plane of the ecliptic Constellations on the ecliptic

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Axial wobble--precession

• http://video.google.com/videoplay?docid=4242610371139275474&q=precession+of+equinox&total=54&start=10&num=10&so=0&type=search&plindex=4

Lab Starts this Week

• Room NS 017• Down the south stairs• Do not miss class the first week• Buy your lab manual and read the first lab• Do the prelab questions, because your lab

instructor may want you to hand them in

Animation link -- http://www.astro.virginia.edu/class/oconnell/astr121/im/lunation-anim.gif

Moon’s Motion

• Rotates on axis once each 27 1/3 days• Same side always faces Earth• No atmosphere—extreme temperature

variation: 127o to -173o C

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Moon

• 3475 km diameter

• Density ~ Earth’s mantle

http://www.astrosurf.com/cidadao/moon_99_03_01.jpg

Meteor Impact Compression Wave

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Ejecta Rim Euler Crater

Lunar Features Maria Formation

Flood Basalt Lunar Exploration

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Footprint in lunar regolith

Moon formation

http://www.psi.edu/hartmann/pic-cat/

Impact of asteroid

http://www.psi.edu/hartmann/pic-cat/

Ejecta from impact

http://www.psi.edu/hartmann/pic-cat/

Coalesced to form Moon

http://www.psi.edu/hartmann/pic-cat/

Moon was initially hot

http://www.psi.edu/hartmann/pic-cat/

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Moon by Apollo

17 CrewRight part of

photo is ‘dark side’that cannot be seen from Earth

http://spacekids.hq.nasa.gov/osskids/animate/moon.html

Rayed Crater

http://cnr2.kent.edu/~manley/copernicus_crater_area.jpg

Lab Starts this Week

• Room NS 017• Down the south stairs• Do not miss class the first week• Buy your lab manual and read the first lab• Do the prelab questions, because your lab

instructor may want you to hand them in