19 June 2014
The Short Answer (TSA)
Full Lunar Eclipse
The word eclipse comes from an ancient Greek word meaning “the darkening of a heavenly body.” For there to be a lunar eclipse, two things must happen. First, the Earth must move in between the Sun and the Moon. Second, the Moon must move exactly into the shadow cast by the Earth.
Lunar Eclipse Illustrated
Lunar eclipses don’t happen that often, but the Earth moves in between the Sun and Moon every month. In fact, the Full Moon is the precise moment when the earth is in between the Sun and the Moon. But Lunar Eclipses are unusual. And they don’t happen with every Full Moon. Why not?
There are two reasons. First, the Earth casts a very small shadow and the Moon is a very small target. Second, the orbit of the Earth around the Sun and Moon’s own orbit around the Earth are not all on exactly a level plane. So, most often, the Earth is a bit above or below the “level” of the Sun — and/or — the Moon is a bit above or below the level of the Sun and Earth.
Diagram Shows Level Plane Differences Between the Earth and the Moon
Again, the Earth casts such a small shadow and Moon is such a small target. So, during most Full Moons, the shadow of the Earth will “miss” and pass just above or below the Moon. So, most often, all we see is the full sunlit face of the Moon.
But, once in a while, the Earth, and Moon will line up on exactly the same level plane. When that happens, a sky watcher will see a Lunar Eclipse. The Full Moon suddenly being covered as a shadow moves across the face of the moon until the whole Moon is completely covered with a dark shadow.
But if you look carefully, you’ll notice that you can still see the faint outline of the darkened Moon. It has a very dark reddish color. From beginning to end, a Lunar Eclipse will last about 1 hour and 45 minutes.
Lunar Eclipse Explained: Video Link
Lots of Moons & Music 