A tetrad of lunar eclipses, starting in April

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Get ready! A tetrad of lunar eclipses, starting in April

 

A total lunar eclipse on April 15, 2014 marks the beginning of a remarkable series of eclipses, all visible from North America.

 

For people in the United States, an extraordinary series of lunar eclipses is about to begin.

The action starts on April 15th when the full moon passes through the amber shadow of Earth, producing a midnight eclipse visible across North America. So begins a lunar eclipse tetrad ? a series of 4 consecutive total eclipses occurring at approximately six month intervals. The total eclipse of April 15, 2014, will be followed by another on Oct. 8, 2014, and another on April 4, 2015, and another on Sept. 28 2015.

 

?The most unique thing about the 2014-2015 tetrad is that all of them are visible for all or parts of the USA,? says longtime NASA eclipse expert Fred Espenak.

On average, lunar eclipses occur about twice a year, but not all of them are total. There are three types:

A penumbral eclipse is when the moon passes through the pale outskirts of Earth?s shadow. It?s so subtle, sky watchers often don?t notice an eclipse is underway.

A partial eclipse is more dramatic. The moon dips into the core of Earth?s shadow, but not all the way, so only a fraction of moon is darkened.

A total eclipse, when the entire moon is shadowed, is best of all. The face of the moon turns sunset-red for up to an hour or more as the eclipse slowly unfolds.

Usually, lunar eclipses come in no particular order. A partial can be followed by a total, followed by a penumbral, and so on. Anything goes. Occasionally, though, the sequence is more orderly. When four consecutive lunar eclipses are all total, the series is called a tetrad.

 

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