Saturday, March 6, 2010

Drawing Space: Part 3

The next set of my A to Z of Astronomy:

Galaxies are collections of billions of stars. There are billions of galaxies. That's a lot of stars, and a lot of planets, and a lot of chances for life out there... Somewhere.

The Horsehead Nebula is a cloud of interstellar dust and gas. It is part of the Orion Complex, about 1500 light years from Earth. The Horsehead is a cloud of dark dust in a much brighter cloud.

Impact craters are much more common and impressive on the moon than on earth for two reasons:
1. The earth has geological processes that slowly wear away craters over the eons. The moon does not.
2. The earth has an atmosphere that destroys many meteors before they impact, and slow down most of the rest so the force of impact is somewhat lessened. The moon does not.
What this means is that anything that heads toward the moon is gonna hit, and gonna hit hard, and the evidence isn't going to be covered up for a very, very, very long time.

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