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[[image:Moon2.jpg|right|thumb|350px|The Moon, age 21 days]]  

[[image:Moon2.jpg|right|thumb|350px|The Moon, age 21 days]]  

The '''Moon''' is a natural satellite orbiting the Earth at an average distance of about 238,000 miles (380,000 km). Its mass is great enough that the earth and the moon both move around a common point located at their common [[centroid|center of mass]] or ''barycenter''. <ref>The Earth and the Moon orbit each other around a gravitational midpoint called the ''barycenter.'' This point is, however, actually inside the Earth, about 3/4 from its center. It is not the Earth, but the barycenter of the Earth/Moon system, that orbits the Sun in a near-perfect ellipse. Relative to this ellipse, Earth is 3,000 miles closer to the Sun at full moon and 3,000 miles further from the Sun at new moon.</ref>

The '''Moon''' is a natural satellite orbiting the Earth at an average distance of about 238,000 miles (380,000 km). Its mass is great enough that the earth and the moon both move around a common point located at their common [[centroid|center of mass]] or ''barycenter''. <ref>The Earth and the Moon orbit each other around a gravitational midpoint called the ''barycenter.'' This point is, however, actually inside the Earth, about 3/4 from its center. It is not the Earth, but the barycenter of the Earth/Moon system, that orbits the Sun in a near-perfect ellipse. Relative to this ellipse, Earth is 3,000 miles closer to the Sun at full moon and 3,000 miles further from the Sun at new moon.</ref>