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[silence]

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[music] Narrator: Using the Lunar Reconnaissance Orbiter's Laser Altimeter,

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NASA scientists have been counting craters to create the first-ever, comprehensive catalog

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of large craters on the Moon. Here, individual craters larger than 20 kilometers

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in diameter "light up" using LOLA elevation data. By studying these data,

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scientists have discovered that, in the Moon's early history, the proportion of large impact craters

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to small impact craters was higher, indicating that proportionally more larger craters were formed

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then. This provides clues to the chaotic early days of the inner solar system, including

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Earth's own history. [beeping]