Astronomy 104: Lecture 3 (Slide 10)

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The Lunar Eclipse:

A Lunar Eclipse occurs whenever the Earth gets between the Sun and Moon.

3 Kinds are Possible:

A Penumbral Eclipse: Moon is slightly above or below the Line of Nodes. Moon slightly dimmed, not blocked
A Partial Eclipse: a portion of the Moon enters the deep shadow. A 'bite' has been taken out of the Moon.
An Umbral (Total) Eclipse: Like the one we just had. The Moon has fully entered the Earth's shadow (or the Umbra). In this case, the Sun is totally blocked and the Moon dims dramatically.

Because the Earth's Shadow is larger than the Moon, a total Lunar Eclipse is visible everywhere on the night side of Earth. In the picture above, the Moon in the Umbral shadow (full Eclipse), but still reflects light! This comes from Earth's atmosphere, which bends (primarily) red light around its edges and onto the Lunar surface.

How long a total Lunar Eclipse lasts depends how close it comes to the center of the Earth's Shadow. It can be up to 1:42 long.

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