Download The Inner Planets

Name ____________________________ Date ____________________ Class ____________
The Solar System
■
Guided Reading and Study
The Inner Planets
This section describes the main characteristics of the four planets closest to the sun.
Use Target Reading Skills
As you come to each major head in the section, stop and write what you know about
that topic. As you read the passage, write what you learn.
What You Know
1. Most of Earth is covered with water.
2.
3.
4.
What You Learned
1.
2.
3.
4.
Introduction
1.
Which planets are often called the terrestrial planets?
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________________________________________________________________________
2.
What are three similarities among the inner planets?
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Name ____________________________ Date ____________________ Class ____________
The Solar System
■
Guided Reading and Study
Use the table “The Inner Planets” in your textbook to answer questions 3 and 4.
3.
Rank the inner planets according to diameter. Rank the planet with the
greatest diameter as 1.
________ Mercury
________ Venus ________ Earth
________ Mars
4.
Which planet rotates on its axis in about the same amount of time that
Earth does? ________________________
5.
The drawing below shows the sun and the four inner planets. Label the
inner planets according to their place in the solar system.
Sun
6.
Circle the letter of each sentence that is true about Earth.
a. About 70 percent of its surface is covered with water.
b. Its atmosphere extends about 1 kilometer above its surface.
c. Most of the atmosphere is composed of oxygen gas.
d. No other planet in the solar system has oceans like Earth’s.
7.
What are the three main layers of Earth?
a. ________________________
b. ________________________
c. ________________________
8.
What is Earth’s dense inner core made of? ________________________
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The Solar System
Earth
Name ____________________________ Date ____________________ Class ____________
The Solar System
■
Guided Reading and Study
The Inner Planets
(continued)
Mercury
9. Circle the letter of each sentence that is true about Mercury.
a. Mercury’s surface has many craters.
b. Mercury has no moons.
c. The interior of Mercury is composed mostly of the element mercury.
d. Mercury is the planet closest to the sun.
10. Why does Mercury have a greater range of temperatures than any other
planet?
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
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Venus
11. Because Venus is often a bright object in the west after sunset, it is
sometimes called the ________________________.
12. Why is Venus sometimes called “Earth’s twin”?
________________________________________________________________________
________________________________________________________________________
13. Circle the letter of the gas that makes up most of the atmosphere of the
planet Venus.
a. oxygen
b. nitrogen
c. sulfuric acid
d. carbon dioxide
14. How is the rotation of Venus different from that of most other planets
and moons?
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15. Is the following sentence true or false? The atmosphere of Venus is so
thick that there is never a sunny day on its surface.
________________________
16. The trapping of heat by the atmosphere of Venus is called the
________________________.
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Name ____________________________ Date ____________________ Class ____________
The Solar System
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Guided Reading and Study
Mars
17. Why is Mars called the “red planet”?
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
18. The atmosphere on Mars is composed mostly of
________________________.
19. Is the following sentence true or false? There are no canals on Mars.
________________________
20. Why do some regions on Mars look darker than others?
________________________________________________________________________
________________________________________________________________________
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21. Circle the letter of each sentence that is true about Mars.
a. The rocks on Mars are covered with a rusty dust.
b. Mars has seasons because it is tilted on its axis.
c. Mars has many large oceans on its surface.
d. Mars has giant volcanoes on its surface.
22. What are the two moons of Mars?
a. ________________________
b. ________________________
Characteristics of Earth and Mars
Characteristic
Earth
Mars
Atmosphere
Mostly nitrogen and oxygen
a.
Moons
One
b.
Seasons
c.
Yes
Surface
Solid and rocky
d.
Water
e.
At poles and possibly
underground
f. Use the table to identify which characteristics of Mars make it difficult or
impossible for humans to live there without life support.
________________________________________________________________________
________________________________________________________________________
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The Solar System
23. Complete the table to compare and contrast characteristics of Earth
and Mars.
Name ____________________________ Date ____________________ Class ____________
The Solar System
■
Section Summary
The Inner Planets
Guide for Reading
■ What characteristics do the inner planets have in common?
■
What are the main characteristics that distinguish each of the
inner planets?
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The Solar System
Mercury, Venus, Earth, and Mars are more similar to one other than they are
to the five outer planets. The four inner planets are small and dense and
have rocky surfaces. These planets are often called the terrestrial planets,
from the Latin word terra, or “earth.”
Earth is unique in our solar system in having liquid water at its
surface. Earth has a suitable atmosphere and temperature range for water to
exist as liquid, gas, or solid. Earth has an atmosphere that is rich in oxygen.
Nearly all of the remaining atmosphere consists of nitrogen, along with
small amounts of other gases such as argon and carbon dioxide. The
atmosphere also includes water vapor.
Mercury is the smallest terrestrial planet and the planet closest to the
sun. Mercury is smaller than Earth’s moon and has no moons of its own. The
planet’s interior is probably made of iron, and its surface has many plains
and craters. Because the planet is so close to the sun, the side facing the sun
reaches temperatures of 430°C. However, the temperature drops to –170°C
at night.
Venus is similar in size and mass to Earth. Venus’ density and internal
structure are similar to Earth’s. But in other ways, Venus and Earth are very
different. Venus rotates from east to west, the opposite direction from most
other planets and moons. The pressure of Venus’s atmosphere is 90 times
greater than the pressure of Earth’s atmosphere. The atmosphere is mostly
carbon dioxide, with clouds partly made up of sulfuric acid. The carbon
dioxide in the planet’s atmosphere traps the sun’s heat, causing the surface
temperature of Venus to be about 460°C. This trapping of heat by the
atmosphere is called the greenhouse effect. Venus is covered with rock,
similar to many rocky areas on Earth. Venus also has many volcanoes and
broad plains formed by lava flows.
Mars is called the “red planet.” Its surface is covered with red dust. The
planet Mars has a very thin atmosphere that is mostly carbon dioxide.
Temperatures on the surface range from –140ºC to 20ºC. Images of Mars
show a variety of features that look as if they were made by ancient streams,
lakes, or floods. Scientists think that a large amount of liquid water flowed
on Mars’s surface in the distant past. At present, liquid water cannot exist
for long on Mars’s surface. However, some water is frozen in the planet’s
two polar ice caps. A large amount of water may be frozen underground.
Like Earth, Mars is tilted on its axis, so its seasons change. Some regions of
Mars have giant volcanoes. Mars has two very small moons, Phobos and
Deimos.
Name ____________________________ Date ____________________ Class ____________
The Solar System
■
Review and Reinforce
The Inner Planets
Understanding Main Ideas
Label the diagram with the names of the inner planets.
1.
2.
3.
4.
Sun
Write the inner planet or planets that the statement describes.
________________________
5. has a rocky surface
________________________
6. 70 percent is covered with water
________________________
7. rotates in the opposite direction from
most other planets and moons
________________________
8. called the “red planet” because of the
color of the dust
________________________
9. has at least one moon
________________________ 10. similar to each other in size, density, and
internal structure
________________________ 11. has almost no atmosphere
________________________ 12. atmosphere is so heavy and thick that it
would crush a human
________________________ 13. has a tilted axis that causes seasons
________________________ 14. atmosphere has low air pressure and is
mostly carbon dioxide
Building Vocabulary
Write a definition for each of the following terms.
15. terrestrial planets
________________________________________________________________________
16. greenhouse effect
________________________________________________________________________
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Name ____________________________ Date ____________________ Class ____________
The Solar System
■
Enrich
Atmospheres of Earth and Venus
Earth and Venus are about the same size. Still, it is hard to imagine how the
conditions on the surfaces of Earth and Venus could be more different.
Earth’s surface is cool, while that of Venus is 460°C. You have learned that
this is because Venus is closer to the sun than Earth and because of the
greenhouse effect caused by the carbon dioxide gas in Venus’s atmosphere.
Earth has a smaller greenhouse effect because there is much less carbon
dioxide in its atmosphere. Why is this so, if the two planets are so similar in
other ways?
Both Earth and Venus get much of their carbon dioxide from the same
source: erupting volcanoes. Unlike on Venus, Earth’s carbon dioxide is
constantly removed from the atmosphere by two things that Venus lacks:
liquid water and green plants. Carbon dioxide dissolves easily in water.
Once it is there, it joins with other chemicals to form solid substances that
become part of sea-floor rocks. This carbon dioxide is trapped unless the
rock melts. As a result, much of Earth’s carbon dioxide is “locked up” in
these rocks. Plants also absorb carbon dioxide and lock up some of the gas.
On Venus, carbon dioxide simply builds up in the atmosphere.
Atmosphere:
0.0035%
ur
S
Oceans:
0.189%
fac
eo
Plants:
0.0069%
Atmosphere:
100%
f Venus
Rocks:
99.8%
Location and pathway of carbon dioxide
at or near the surface of Venus
Figure 1
Figure 2
Use the diagrams to answer the questions below on a separate sheet of paper.
1. Figure 1 shows, in very simple terms, the pathways taken by carbon
dioxide on Earth. According to the diagram, where does carbon dioxide
go when it leaves Earth’s atmosphere?
2. On Earth, where is most of the carbon dioxide located at any one time?
On Venus, where is most of the carbon dioxide located at any one time?
3. On Earth, how does carbon dioxide move from the atmosphere into
rocks? Why does this movement not occur on Venus?
4. If the temperature of Earth’s surface were to increase by 100°C, what
would happen to the amount of carbon dioxide in the atmosphere? Why?
5. If all carbon dioxide coming out of volcanoes were to remain in the
atmosphere, what further effect would this have on Earth’s temperature?
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The Solar System
Location and pathway of carbon dioxide
at or near Earth's surface