Earth Science Practice Test: The Solar System
- The Solar System
- 10 questions
- 15 minutes
This test covers the Sun, the planets and the smaller bodies that orbit it. Tip: for Moon phases and eclipses, sketch the Sun, Earth and Moon in a line before you answer.
Tap an option to mark your answer. You can change your mind, or tap the same option again to leave the question blank. The correct answers and explanations appear when you finish the test.Tap an option to answer; tap it again to leave the question blank.
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Question 1
Which group lists only the inner, rocky (terrestrial) planets?
Correct answer: B
The four planets closest to the Sun, Mercury, Venus, Earth and Mars, are small and made of rock and metal. Jupiter, Saturn, Uranus and Neptune are the large outer giants.
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Question 2
Which planet has the hottest average surface temperature?
Correct answer: C
Venus has a thick carbon dioxide atmosphere that traps heat through a strong greenhouse effect, making it hotter than Mercury even though Mercury is closer to the Sun. Mercury has almost no atmosphere and loses heat on its night side.
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Question 3
Which is the largest planet in the solar system?
Correct answer: A
Jupiter is the largest planet, with a diameter about 11 times Earth's and more mass than all the other planets combined. Saturn is second.
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Question 4
What keeps the planets moving in orbit around the Sun?
Correct answer: D
The Sun's gravity constantly pulls each planet toward it, while the planet's forward motion keeps it from falling in. Together they produce a curved, nearly circular orbit.
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Question 5
Why does the Moon go through phases?
Correct answer: B
The Sun always lights half of the Moon. As the Moon orbits Earth over about a month, we see more or less of that lit half. Earth's shadow falls on the Moon only during a lunar eclipse.
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Question 6
A lunar eclipse happens when:
Correct answer: D
In a lunar eclipse, Earth blocks sunlight from reaching the Moon, so it can happen only at full moon. The Moon passing between the Sun and Earth at new moon causes a solar eclipse.
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Question 7
Which of these planets takes the longest to complete one orbit around the Sun?
Correct answer: A
Planets farther from the Sun travel a longer path and move more slowly, so their years are longer. Saturn, the farthest of these, takes about 29 Earth years per orbit; Mercury takes only 88 days.
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Question 8
The Sun is about 150 million km from Earth. Light travels about 300,000 km per second. About how long does sunlight take to reach Earth?
Correct answer: C
150,000,000 km ÷ 300,000 km/s = 500 seconds, which is about 8.3 minutes. The answer of 8 seconds comes from forgetting to convert the units correctly.
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Question 9
Where is the main asteroid belt located?
Correct answer: D
Most asteroids orbit in a wide band between Mars and Jupiter. The region beyond Neptune is the Kuiper Belt, home to icy bodies such as Pluto.
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Question 10
A comet is moving away from the Sun after passing close to it. In which direction does its tail point?
Correct answer: A
Sunlight and the solar wind push gas and dust away from the comet, so the tail always points away from the Sun. When the comet is leaving, the tail actually leads in front of it.
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