In a week of ridiculously gorgeous astronomy pictures hitting the ‘net, I keep thinking they can’t get cooler… and then this happens: a seriously cool picture of the Sun from NASA’s Solar Dynamics Observatory!
Yegads! [Click to solareclipsenate.]
Given that SDO orbits the Earth and sees the Sun from space, why is the bottom half of the Sun gone in this picture? It’s because we’re seeing a solar eclipse which is actually more like a lunar eclipse except the Moon is not involved.
Hmm, yeah, maybe I’d better explain.
SDO circles the Earth in an inclined orbit*. If the orbit were directly above the Earth’s equator, the Earth would block the Sun once per day, and that’s not so cool for a satellite designed to continuously observe our nearest star! So the orbit was inclined a bit, giving SDO an unobstructed view of the Sun… kinda. Because of the way the orbits work out, twice a year there is a period where the orbit of the Earth around the Sun and SDO around the Earth line up, and for brief times the Earth does block the ...
Full story at http://blogs.discovermagazine.com/badastronomy/2011/04/01/when-the-earth-takes-a-bite-out-of-the-sun/
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