Chapter 3 Lesson 2

The Terrestrial Planets

A. Expert - I have done a lot of reading in this area already.

B. Above Average - I have learned some information about this topic.

C. Moderate - I know a little about this topic.

D. Rookie - I already forgot what we talked about last week

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Chapter 3, Lesson 2

Lesson Overview

Know About

Earth

Mercury

Venus

Mars

Chapter 3 Lesson 2

Who discovered the Terrestrial Planets?

Chinese, Greeks, Romans…no one knows

Noticed bright lights “wandered” differently than

stars

So far no human has set foot on any other planet

But we have probes sent back photos/data

that greatly improve our understanding

The word Planet is Greek

for “wandering star” https://airandspace.si.edu

Chapter 3, Lesson 2

The View of Mercury

from Earth

Because Mercury is closest to the Sun you

can only see it shortly before dawn or after

dusk when the Sun is below the horizon

Chapter 3, Lesson 2

Mercury’s Rotation and Orbit

Around the Sun

Smallest planet roughly the size of the Atlantic Ocean

Mercury has the quickest orbit, circles the Sun quickly (88 days)

Mercury rotates on its axis once every 59 Earth day

The planet rotates one and a half times for every time it goes around the Sun

Strong gravity results in smaller craters and less debris spread from meteorites

Mercury is the fastest planet

traveling at 107,000 MPH

Chapter 3 Lesson 2

Mercury

Chapter 3, Lesson

The View of Venus from

Earth

The second closest planet to the Sun

Except for the Sun and Moon, it’s the brightest planet in the sky During WWII fighter pilots

sometimes shot a Venus confusing it with enemy planes

It is visible only in the evening after sunset and in the morning sky before sunrise

Courtesy of NASA/JPL

Chapter 3, Lesson 2

Venus’s Density and

Magnetic Field

Venus is often called Earth’s sister planet

Diameter is 95 percent of Earth’s

Mass is 82 percent of Earth’s

Its orbit is located closest to the Earth

Density 5.24 times that of water

• Similar density as Earth-5.52)

Slow rotation of 243 days

Orbits sun in 225 days

Chapter 3, Lesson 2

Venus’s Rotation and

Orbit Around the Sun

More circular orbit than any other planet

Venus rotates backwards

While all eight planets revolve around

the Sun in a counterclockwise fashion,

Venus and Uranus are the only two that

rotate in a clockwise fashion

Chapter 3, Lesson 2

Venus’s Surface and

Atmosphere

All of Venus is drier than the driest desert on Earth

Venus has about a thousand craters

Venus has an atmosphere made up of about 96 percent carbon dioxide, 3.5 percent nitrogen and small amounts of water and sulfuric acid

Atmosphere is full of corrosive substances that can dissolve lead

Courtesy of NASA/JPL

Venus

Chapter 3 Lesson 2

Chapter 3, Lesson 2

Mars…the Red Planet

Opposition—when a

planet is directly opposite

the Sun in the sky (from

earth’s perspective)

The best time to look at

Mars

Mars is in opposition about

every 2.2 years 13 Oct 2020

07 Dec 2022

15 Jan 2025

19 Feb 2027

Courtesy of NASA/ESA/The

Hubble Heritage Team,

STScI/AURA/J. Bell, Cornell

University/M. Wolff, Space

Science Institute

Courtesy of NASA

Courtesy of

inthesky.org

Opposition

Chapter 3 Lesson 2

Courtesy of NASA

https://www.universetoday.com/wp-

content/uploads/2016/05/Mars-at-opposition.jpg

Chapter 3, Lesson 2

Mars’ Density and Magnetic Field

Diameter about half of the Earth’s

Mass is only one-tenth that of Earth

Scientists calculate that Mars’ density is

3.93 times that of water, about 0.7 of

Earth’s density

Mars rotates almost as quickly as Earth

Chapter 3, Lesson 2

Mars’ Density and Magnetic

Field, cont.

Mars doesn’t have a magnetic field

Mars probably lost its magnetic field about 4 billion years ago

The Sun’s solar wind erodes Mars’ atmosphere and contributes to its loss of water Courtesy of ESA/DRL/FU Berlin

(G. Neukum)

Water/ice near Mar’s North Pole

Chapter 3, Lesson 2

Mars’ Surface and

Atmosphere

Olympus Mons is the largest known mountain

in the Solar System

15 miles high

Liquid water played an important role in

shaping the planet’s surface

Thin atmosphere reason for extreme difference

in temperature

Courtesy of NASA/JPL-Caltech

Dry Riverbed on mars

Mars

Chapter 3 Lesson 2

A. Mars

B. Mercury

C. Earth

D. Venus

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A. Mars

B. Mercury

C. Moon

D. Venus

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A. During Earth’s winter solstice

B. When Mars is in opposition

C. At the beginning of Earth’s fall equinox

D. During Mars’s summer

A. Earth

B. Mars

C. Mercury

D. Venus

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A. Solar winds

B. Sulfuric acid

C. Iron and sulfur

D. Gravitational pull

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What drives people to explore?

If you got the chance to visit space, where would you want to go and

why?

Note to Instructors: Click the Show/Hide Response Display Button

Summary

Mercury

Venus

Mars

Chapter 3, Lesson 2

Next…

Done – The

Terrestrial Planets

Next – The Outer

Planets

Chapter 3, Lesson 2 Courtesy of Amy Simon (Cornell U.),

Reta Beebe (NMSU), Heidi Hammel

(Space Science Institute, MIT)

Chapter 3, Lesson 2

Activity 2: Comparing Earth to

the Terrestrial Planets

Using your text (pages 95-112), complete

the table comparing Earth to the

Terrestrial planets

Then answer the reflection questions

Be prepared to share your answers