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The Stages of a Lunar Eclipse

Earth always has a shadow created by the light from the sun. A lunar eclipse occurs when the moon passes through the Earth's shadow. An eclipse of the moon can only take place during a full moon. Earth blocks the sun's rays from illuminating the moon, and the moon appears enveloped in darkness. A lunar eclipse can be seen anywhere from the night side of Earth.

Moon in the First Penumbra
- The moon orbits Earth at an average speed of 2,300 mph.
  
  The first stage of a lunar eclipse occurs when the moon enters and is in the first penumbra. The penumbra is the shadowy region in which the Earth blocks only some of the sun's rays. The lunar eclipse is beginning when it is in penumbra, however, the moon looks almost the same as when the moon is in the sun's full light.
Moon in Umbra
- The moon's gravitational pull on Earth is the main cause of ocean tides.
  
  The umbra is the region where all of the sun's rays are blocked. When the moon passes through the umbra it is in the peak of its eclipse and will become fully enveloped in darkness. This process may last hours, whereas solar eclipses may last merely minutes.
Moon in Umbra Part 2
- The moon's surface gravity is 1/6th that of Earth's surface gravity.
  
  Lunar eclipses have varying characteristics. When the whole of the moon is in the umbra, a total lunar eclipse can occur. The coloring and darkness of the eclipse can vary due to weather and atmospheric conditions, and the location of the observer. Deep apricot and violet colors have been observed in the past.
The Moon in the Last Penumbra
- The moon is about the same age as Earth -- 4.6 billion years old.
  
  As the moon enters the last penumbra, the lunar eclipse is ending. The shadow will fade from the moon's surface, and the moon will return to its normal appearance. Lunar eclipses recently occurred on June 15, 2011 and December 21, 2010.

Astronomy