How Lunar Eclipses Work

A lunar eclipse occurs when the Moon passes through Earth's shadow, everyone living on the "night side" of Earth are able to see it. The different phases of the eclipse occur all at the same time (unlike solar eclipses, where all earthly observers see different things depending on their location). A lunar eclipse can only occur at full moon.

The shadow cone

In space, a large shadow cone surrounded by a penumbra cone lags behind Earth. Every two years, the Moon’s orbit around Earth passes through this shadow cone. Unlike solar eclipses, which are visible only to a very small area of the surface of the Earth, lunar eclipses are visible to the entire half of the Earth that is plunged into the night for a simple reason; the cone shadow of the Earth is large enough to make the Moon's movement visible to all land located on the dark side of Earth at the time of the eclipse.

The red moon

The beautiful red color of the Moon is actually due to the Earth's atmosphere, which absorbs most of the sun's rays, particularly the blue wavelengths. Only the very reddest of the wavelengths of the sun's rays are able to pass through the protective barrier of our atmosphere and reach the moon, which can then reflect them.

Lunar eclipses remain very beautiful and fascinating phenomena, whether you are interested in the scientific or romantic aspect, do not miss the chance to catch the next lunar eclipse on December 10, 2011.