The Moon [mōōn]

The celestial body that revolves around the earth.

The moon is 1/4 the size of the Earth, and our closest and only natural satellite. The moon is very different from earth — it has no atmosphere, extreme temperatures, only one-sixth of the earth's gravity, and if water exists, it's only as ice at the moon's north and south poles. But, the earth and moon are alike in one way — lunar rock collected by the Apollo astronauts is similar to rock on Earth, suggesting that Earth and its moon were formed from the same material.

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