MNN Galleries

How much do you know about the moon?

Composite photograph of a lunar eclipse

Photo: Russ Wright/Flickr

7 of 12

Lunar eclipse

A lunar eclipse occurs when the Earth perfectly blocks the sun's light from illuminating the moon in a straight-line, "syzygy" configuration. (This occurs during a full moon but is much less common, by the way.) When the moon passes through the Earth's umbra, it's a total lunar eclipse. Sometimes, the moon passes through the penumbra (the part of the Earth's shadow that isn't totally dark) for a penumbral eclipse, but total penumbral eclipses are rare.