2 (g) The Moon's Rotation and Revolution
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Motions of the Moon; Like Earth, the moon moves through space in two ways. The moon revolves around Earth and also rotates on its own axis. It takes the moon about 27.3 days to revolve around Earth.
The moon rotates slowly on its own axis once every 27.3 days. Because the moon also revolves around Earth every 27.3 days, a “day” and a “year” on the moon are the same length. For this reason, the same side of the moon always faces Earth. As the moon revolves around Earth, the relative positions of the moon, Earth, and sun change. The changing relative positions of the moon, Earth, and sun cause the phases of the moon, eclipses, and tides.
The moon rotates slowly on its own axis once every 27.3 days. Because the moon also revolves around Earth every 27.3 days, a “day” and a “year” on the moon are the same length. For this reason, the same side of the moon always faces Earth. As the moon revolves around Earth, the relative positions of the moon, Earth, and sun change. The changing relative positions of the moon, Earth, and sun cause the phases of the moon, eclipses, and tides.