Tuesday, April 15, 2014
What Would the Lunar Eclipse Have Looked Like from the Moon?
We who live in North or South America (and had clear skies,) experienced a total eclipse of the Moon Tuesday morning, April 15. But what would the eclipse have looked like to someone on the Moon?
First, since the Moon always keeps one side toward the Earth and one side away from the Earth, we have to pick a side. For this purpose, the interesting side of the Moon is the one that was facing the Earth and the Sun. It was sunny and bright on that side of the Moon before the eclipse began. Then, an observer on the Moon would have seen the Earth move in front of the Sun, and darkness descend. It would have gotten colder too without the warmth of the Sun.
Since the nearby Earth looks bigger from the Moon that the Sun does, the Earth more than covered the Sun. Still, the Earth's atmosphere bends some of the sunlight behind it toward the Moon. So someone on the Moon would have seen a faint ring of light around the dark Earth. (If you had a telescope on the Moon, you might also have seen the lights of big cities and large fires on the night side of our planet.)
How do we know that this "Moon perspective" about the eclipse is right? A Japanese spacecraft called Kaguya captured just this kind of image during a lunar eclipse in February 2009, as it was orbiting the Moon. In the picture above (courtesy of the Japanese Space Agency), you see several views of the Earth from the Moon during the eclipse. The ring of light is not complete, because some part of Earth was below the Moon's horizon as seen by Kaguya. At the end of the eclipse, you can see the first light of the Sun coming out from behind the Earth, making a kind of diamond ring effect. How wonderful that our robot spacecraft can give us views in the solar system that earlier scientists could only imagine!