Transcription: A planet's gravity is determined by its mass and by the distance from its surface to its center of mass. The mass of the Moon is only one-eightieth the mass of Earth, but its gravity is much more than one-eightieth the Earth's gravity because the Moon's surface is four times closer to its center of mass. As a result, the Moon's gravitational force is only one-sixth as strong as the Earth's, so objects weigh one-sixth as much on the Moon.
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