The Full Moon
April 1999
The Moon glows by light it reflects from the Sun and is frequently the brightest object in the night sky. The Moon orbits the Earth about once a month (moon-th) from about 1 light second away.
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Image Credit: Lick Observatory
 

The Moon glows by light it reflects from the Sun and is frequently the brightest object in the night sky. The Moon orbits the Earth about once a month (moon-th) from about 1 light second away. The above-pictured Full Moon occurs when the Moon is nearly opposite to the Sun in its orbit. The Moon's diameter is about 1/4 that of the Earth, and from the Earth's surface appears to have almost exactly the same angular size as the Sun. Recent evidence indicates that the Moon formed from a colossal impact on the Earth about 4.5 billions of years ago, and therefore has a similar composition to the Earth.  
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