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Inquiry Master 8
Sun-Earth-Moon System Review (Anticipated Responses)
1. Why do we experience day and night?
(Half of Earth is always illuminated by the Sun,
while the other half of Earth is in its own shadow, and is dark. As an area on Earth rotates into
the Sun’s light, that area experiences daylight.
As an area on Earth rotates away from the Sun’s
light, that area experiences night. The length of
day and night for an area changes depending on
Earth’s position relative to the Sun during
Earth’s revolution. During the equinoxes, all
areas on Earth experience 12 hours of daylight
and 12 hours of nighttime.)
2. Define the terms “rotation” and “revolution”
as they relate to space science. (Rotation
defines a planet’s or moon’s spin on its axis.
Revolution defines a planet’s or moon’s orbit
around another solar system body.)
3. Describe the Moon’s period of rotation and
revolution. (The Moon’s period of rotation on
its spin axis is 27.3 days. This is equal to its
period of revolution around Earth [27.3 days];
therefore, only one side of the Moon faces Earth
[the “near side”].)
4. Describe the relative size and distance relationships among the Sun, Earth, and Moon.
(The Moon is 384,000 km away from Earth, or
30 Earth-diameters away. The Earth is 150
million km away from the Sun. The Sun is
1,392,000 km in diameter, which is 400 times
greater than the Moon’s diameter of 3,500 km.
The Sun is also 400 times larger in diameter
than the Moon. The Moon is approximately
one-fourth [0.27] the size of Earth, whose
equatorial diameter is 12,756 km. Nearly 109
Earth-diameters would fit across the diameter
of the Sun.)
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5. Why can the Moon appear as large as the
Sun even though we know the Moon is much
smaller than the Sun? (The Sun is 400 times
farther away from Earth than the Moon, and the
Sun is also 400 times larger in diameter than
the Moon. This causes the two bodies to appear
to be the same size.)
6. Why do shadows change during the day?
You may draw a picture to show changes in
shadow length relative to the Sun’s position in
the sky. (As Earth rotates on its axis, the Sun
appears to move across the sky. Shadow lengths
depend on the apparent position of the Sun in
the sky. When the Sun’s apparent position in
the sky is high [solar noon], shadows are short.
When the Sun’s apparent position in the sky is
lower, shadows are longer.)
7. Explain why shadow lengths change
throughout the year. (Shadow lengths change
throughout the year as Earth orbits the Sun
and Earth’s position on its tilted axis changes
relative to the Sun. When an area on Earth is
tilted toward the Sun [summer in that hemisphere], the apparent position of the Sun is
highest in the sky and solar-noon shadows are
shortest. When an area on Earth is tilted away
from the Sun [winter in that hemisphere], the
apparent position of the Sun is lowest and
shadows are longest.)
8. What causes seasons? (Seasons occur due
to the tilt of Earth’s axis relative to the Sun. As
Earth orbits the Sun, different parts of Earth get
more or less direct sunlight.)
(continued)
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LESSON 8
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Inquiry Master 8 (continued)
9. What factors (other than the one you listed
in Question 8) affect how hot or cold it is in
any one place on Earth? (The atmosphere and
its weather, angle of sunlight, length of day, surface composition, and oceans all play a key role
in daily temperatures.)
10. Looking at the Moon from space, how much
of the Moon always receives light from the
Sun? Explain your answer. (Looking at the
Moon from space, half of the Moon is always
illuminated by the Sun, unless there is a lunar
eclipse. Students may draw a picture of this as
well. See Figure 5.3 and the inner circles of
Inquiry Master 5.2 for an example.)
11. Sketch and label the phases of the Moon.
Waning
Crescent
Third
Quarter
Waning
Gibbous
New
Moon
SUN
EARTH
Waxing
Crescent
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First
Quarter
Full
Moon
Waxing
Gibbous
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LESSON 8
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Inquiry Master 8 (continued)
12. Draw a diagram of each eclipse listed below. Make certain to show the lighter and darker
portions of the eclipse shadow. Label the Moon, Sun, and Earth, umbra and penumbra, and
indicate where there is a partial or total eclipse.
Partial
solar
eclipse
Total
solar
eclipse
Earth
Penumbra
Umbra
Moon
Sun
Solar eclipse
Penumbra
Umbra
Earth
Moon (in total lunar eclipse)
Sun
Lunar eclipse
(continued)
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Inquiry Master 8 (continued)
13. Why do solar and lunar eclipses occur?
(Although the Moon’s orbit is tilted, two to five
times a year the Moon crosses over Earth’s
orbital plane at the same time that the Moon,
Earth, and Sun align. During this alignment, the
Moon’s shadow falls on Earth and causes a solar
eclipse, or the Moon passes into Earth’s shadow
and a lunar eclipse results. The type of eclipse
that occurs depends upon the position of the
Moon or Earth within the umbra and penumbra
of the shadow.)
14. During which phase of the Moon does a
solar eclipse occur? During which phase of
the Moon does a lunar eclipse occur? (A solar
eclipse occurs during a new moon. A lunar
eclipse occurs during a full moon.)
15. Why don’t we have eclipses every month?
(The Moon’s orbital plane is tilted. This means
that when the Moon passes between the Sun
and Earth, its shadow normally falls into space
below or above Earth. The same occurs when
the Earth is between the Moon and Sun; the
Moon normally passes above or below Earth’s
shadow.)
16. What is the source of energy for the Earth?
(The Sun provides the primary source of energy
for Earth.)
18. What can you conclude from your observations of sunspots? (Sunspots are part of the
Sun’s surface and move across the Sun’s surface
from west to east, which indicates that the Sun
rotates on its axis counterclockwise relative to
its northern pole. Sunspot groups can be tracked
over days. The number of sunspots changes from
day to day and from year to year. Sunspot maximums and minimums occur on 11-year cycles.)
19. What is space weather? How does it affect
Earth, including its space environment?
(The term “space weather” includes conditions
on the Sun and in the Sun’s extended atmosphere. Space weather affects our atmosphere,
equipment, and space operations. The particles
energized by the solar winds affect spacecraft,
humans in space, and occasionally human
activities on Earth. They even cause changes
in the space environment, which we see as
auroras.)
20. What are auroras and how do they form?
(If you haven’t done so already, read ahead to
“Auroras” in Lesson 8 to answer this question.)
(Auroras are light displays that occur mostly
near the poles when gases in Earth’s atmosphere
glow when hit by charged particles carried by
solar winds.)
17. How is Earth protected from receiving too
much solar radiation? (Earth’s atmosphere
absorbs, reflects, and scatters the Sun’s incoming
radiation.)
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LESSON 20
E X P L O R I N G S PA C E T E C H N O L O G Y
Inquiry Master 20
Solar System Review: Answer Key
Directions Review the reading selections in your Student Guide, your notes, and your student
sheets in Lessons 11–21 to prepare for the assessment in Lesson 22. Complete the following questions to prepare for the assessment.
1. List the planets in order according to their distances from the Sun. Tell which planet receives
the most light from the Sun, and why. (Lesson 11)
(Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto are the nine planets.
Mercury is closest to the Sun and receives more of the Sun’s concentrated light.)
2. Use the scale factor 1 cm = 400 km to estimate how big a model of Earth should be. (Hint: First
look up Earth’s diameter. Then divide by 400km/cm. Watch your units.) (Lesson 11)
(12,756 km ÷ 400 km/cm = 30 cm)
3. Why is it difficult to create an accurately scaled model of the solar system in the classroom?
(Lesson 11)
(The distances between the planets are so vast.)
4. How are impact craters formed? Draw a crater and label its parts. (Lesson 12)
(Craters are formed when asteroids, meteorites, or comets strike the surface of a planet, moon, or
asteroid. See SG Lesson 12 for a drawing of a crater and its labeled parts.)
5. Why are the craters on Earth’s surface less evident than those on other terrestrial planets’
surfaces? (Lessons 12 and 13)
(The processes of wind erosion, water erosion, volcanism, and tectonics have erased evidence of
many impact craters on Earth. Landforms wear down as new landforms are created by tectonics
and volcanism. This process occurs over and over.)
6. Other than the nine planets, what objects are in the solar system? (Lessons 1–8, 12, and 17)
(The solar system includes the Sun, the Moon, Earth and eight other planets and their moons, and
smaller objects such as asteroids, meteoroids, and comets, but it is mostly empty space.)
(continued)
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Inquiry Master 20 (continued)
7. Complete Table 1 Planetary Processes by listing two planetary processes in the first column.
Describe the landforms created by each process in the second column. In the last column, name
one or more planets on which this process and/or landform can be found. (Lesson 13)
(Answers will vary. A sample response is given.)
Table 1 Planetary Processes
Planetary Process
Landform Created
by This Process
Planet Where This Process
or Landform Exists
wind erosion
dunes
Earth, Mars
tectonics
mountains, ridges
Earth, Venus
8. Describe how gravity affects an apple falling from a tree. (Lesson 14)
(Gravity acts on the apple at all times—when the apple is hanging from the tree, when it is falling
from the tree, and as it reaches the ground.)
9. Describe the difference between mass and weight. (Lesson 14)
(Mass is a measure of the amount of matter in a body. Weight is the measure of the force of gravity on a body.)
10. Why would a can of soda weigh different amounts on each planet? (Lesson 14)
(Weight is a measure of the force of gravity on a body. The surface gravity on each planet is different because each planet has a different diameter and mass.)
11. How does the mass of a planet affect the speed of a moon that orbits it? (Lesson 15)
(If all other variables were held constant, the greater the mass of a planet, the greater the gravitational influences a planet will have on the moon in orbit around it. A moon will orbit a planet at
a faster rate if the planet is more massive. Jupiter’s Io is an example.)
12. What happened to your orbiting marble when you lifted up the metal ring? Explain why this happened. (Lesson 15)
(The marble moved in a straight path. This happened because the ring—which served as an
unbalanced force—was removed.)
(continued)
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LESSON 20
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Inquiry Master 20 (continued)
13. Describe the motion of a planet when it orbits a star. (Be specific. How is the motion of a planet
near the star different from the motion of a planet far from the star? What is the shape of
a planet’s orbit?) (Lesson 15)
(The planet will orbit the star somewhat in an ellipse. The closer the planet is to the star, the
faster the planet’s orbital speed.)
14. Why are there usually two high tides and two low tides each day? (Lesson 16)
(As Earth rotates on its axis, tides occur in pairs on opposite sides of the planet due to the Moon’s
[and to a lesser extent, the Sun’s] gravitational influence. A pair of high tides occurs along the
line that joins the Moon and Earth [with some tidal lag]. A pair of low tides occurs at right angles
to the line that joins the Moon and Earth.)
15. What did Eugene Shoemaker, his wife Carolyn Shoemaker, and David Levy witness in 1994?
(Lesson 17)
(A comet strike Jupiter)
16. Compare asteroids, comets, meteoroids, and meteors. (Lesson 17)
• Asteroid A relatively small, rocky body in an independent orbit around the Sun
• Comet A relatively small object whose ices can sublimate in sunlight, forming an atmosphere (coma) of dust and gas, and sometimes a tail of dust and/or gas
• Meteoroids A small piece of asteroid, comet dust, or other space debris
• Meteor The light phenomena which results when a meteoroid enters Earth’s atmosphere
and vaporizes; a “shooting star”
17. How have asteroid impacts influenced Earth’s history as a planet? Give one example.
(Lesson 17)
(Asteroid impact can be catastrophic, nearly wiping out life on Earth at the time of impact. The
asteroid that struck Earth 65 million years ago in what is now the Yucatan Peninsula is an
example. This asteroid probably caused the dinosaurs’ extinction.)
18. Describe what happens to a comet as it nears the Sun. (Lesson 17)
(As a comet nears the Sun, pressure from the Sun may send dust and gas streaming away from
the comet, forming its tail. The tail [usually two] of a comet always faces away from the Sun.)
19. What are fossils, and why are they important to the study of Earth’s history as a planet?
(Lesson 18)
(Fossils are the remains of once-living organisms. Fossils provide a record of life on Earth in the
past.)
(continued)
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Inquiry Master 20 (continued)
20. What is the difference between a fossil cast and a mold? (Lesson 18)
(In a mold, the impressions of organisms are left after they are covered by soft material. If sand
or other minerals fill the cavity-shaped mold over time and then hardens, a replica—or cast—of
the original organism forms.)
21. Name one reason why life, as we know it, cannot exist on Venus. Then name one reason why
life can exist on Earth. (Lesson 19)
(Life as we know it could not tolerate Venus’s extremely high surface temperatures. Earth contains water in three states—liquid, solid, and gas. Earth also contains abundant oxygen, which
helps sustain life on Earth as we know it.)
22. Describe Venus’s atmosphere and the gases that make up its atmosphere. Why does Venus have
a runaway greenhouse effect? (Lesson 19)
(Venus’s atmosphere is rich in carbon dioxide, which allows solar radiation to come in to its
atmosphere, but keeps radiated heat from escaping, causing a greenhouse effect on Venus. This
effect accounts for Venus’s high surface temperatures.)
23. What is a space spinoff? Give one example. (Lesson 20-21)
(A space spinoff is a product or service originally designed for space that has been adapted for
use here on Earth. A ski boot, adapted from the technology used to design the boot used on the
Moon, is one example.)
24. How has the technology of space exploration been used to help improve everyday life?
(Lesson 20–21)
(Answers will vary. One example is through satellites, which help us communicate, predict
weather, and determine exact locations on Earth.)
25. How did Copernicus’s view of the solar system differ from Ptolemy’s? (Look back in Lesson 1.)
(Copernicus believed that the Sun was the center of the solar system; Ptolemy believed that Earth
was the center of the solar system and that all planets and the Sun revolved around Earth.)
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