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What's your favorite part of Autumn? Color in the trees? Cool weather? Jumping into a big pile of leaves? Well, this fall we get something extra we can enjoy: a total lunar eclipse. The eclipse starts around 4 A.M. EDT (1:16 A.M. PDT) on October 8th, and will be visible anywhere in North America. However, you won't notice much of a difference in the coloration of the Moon until it passes through the outer part of the Earth's shadow, the penumbra, into the inner part of the Earth's shadow, the umbra, around 5 A.M. EDT (2:15 A.M. PDT).
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The mechanics of a lunar eclipse. Showing how the longer red wavelengths are bent around the earth as a result of it's atmosphere, reaching the Moon.
mars.nasa.gov
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Once the Moon passes into the umbra, it will be there for about an hour and ten minutes, so you'll have that long before it moves on and out. Once totality approaches, when the Moon is totally obscured from the Sun, no direct sunlight reaches it. So this raises the question, "Why does the Moon look red during a lunar eclipse?" This is where it get's interesting. The Moon appears red because sunlight that hits the Earth's atmosphere is bent around the planet, and strikes the Moon behind it. Why red though? Why not blue? Red has a longer wavelength, whereas blue has a shorter wavelength. So any blue light is scattered throughout the atmosphere, and dissipates. The red light passes on through the atmosphere, and out to the Moon due to it's longer wavelength.
People in North America aren't the only ones who can witness the eclipse. Anyone on islands in the Pacific Ocean will also get a fantastic view. For those in Asia, New Zealand, and Australia, the eclipse will occur on the evening of October 8th.
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