Earth Shadow Direction on Lunar Eclipse
Date: Winter 2011-2912
Watching the lunar eclipse yesterday morning near Salt Lake City, Utah, I was surprised to see the darkness proceed from the top of the moon down to its "south" pole. Since the moon is travelling in orbit more or less horizontal to the earth's equator I would have expected the darkness to start on one side of the moon and proceed to the other--from the moon's "east" side to its "west" side as it entered Earth's shadow. Why did the shadow go from north to south?
The Moon really slid into Earth's shadow from northwest to
southeast. The Moon's orbit makes it shift a bit in declination. I
am glad you saw this eclipse; hope you enjoyed it! It was my 80th eclipse.
Daviid H. Levy
The shape of Earth's shadow is a cone. The moon can be entering and
leaving the shadow not along the Moon's equator.
---Nathan A. Unterman
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Update: June 2012