Space is being ridiculous again.
A sideways planet, a slow spinner, and other cosmic surprises.
Ten questions, with the answers explained. Try them in your head, then open each answer when you're ready.
Play this quiz →QUESTION 1 / 10
Which planet takes longer to rotate once on its axis than to orbit the Sun?
- Earth
- Mars
- Jupiter
- Venus
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Venus
Venus rotates once in about 243 Earth days and orbits in about 225. A sunrise-to-sunrise solar day is a different measure.
QUESTION 2 / 10
Which planet spins almost on its side?
- Uranus
- Mercury
- Earth
- Mars
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Uranus
Uranus has an extreme axial tilt, giving it unusually dramatic seasons.
QUESTION 3 / 10
Which planet is hottest at its surface on average?
- Neptune
- Venus
- Mercury
- Mars
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Venus
Venus's dense atmosphere traps heat. Being closest to the Sun does not make Mercury the hottest.
QUESTION 4 / 10
Which is the largest planet in our solar system?
- Neptune
- Earth
- Jupiter
- Saturn
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Jupiter
Jupiter is the largest planet in our solar system.
QUESTION 5 / 10
Which planet has Olympus Mons, a giant volcano?
- Venus
- Saturn
- Mercury
- Mars
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Mars
Olympus Mons is a massive shield volcano on Mars.
QUESTION 6 / 10
What is a light-year actually measuring?
- Distance
- Time
- Brightness
- Temperature
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Distance
A light-year is the distance light travels in one year.
QUESTION 7 / 10
What powers the Sun's energy output?
- Reflected starlight
- Nuclear fusion
- Burning coal
- Chemical batteries
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Nuclear fusion
Fusion in the Sun's core turns hydrogen into helium and releases energy.
QUESTION 8 / 10
Why does the Moon shine in the night sky?
- Its surface is electric
- It makes visible light by fusion
- It reflects sunlight
- It burns like a star
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It reflects sunlight
The Moon's bright surface is reflecting light from the Sun.
QUESTION 9 / 10
What is between Mars and Jupiter?
- Saturn's rings
- The Kuiper belt
- Earth's orbit
- The main asteroid belt
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The main asteroid belt
The main asteroid belt lies between the orbits of Mars and Jupiter.
QUESTION 10 / 10
Which of these is a star?
- The Sun
- Venus
- The Moon
- Jupiter
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The Sun
The Sun is a star. The others are a planet, a moon, and another planet.