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The Milky Way is one of over a trillion ____ in the Universe.
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asteroids
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Most ____ originate in the Kuiper belt or the Oort cloud.
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comets
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Millions of ____ (huge rocks) orbit between Mars and Jupiter.
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galaxies
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Stars arise in freezing clouds of dust and gas known as ____.
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meteorites
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Meteoroids that enter the Earth's atmosphere are called ____.
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meteoroids
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Meteors that reach the Earth's surface are called ____.
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meteors
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When asteroids smash together, ____ (small rocks) break off.
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moons
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Galileo discovered Jupiter's four largest ____ in 1610.
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nebulae
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