Friday, November 05, 2010

Amazing close-ups of comet Hartley 2!

NASA spacecraft EPOXI passed just 700 km from the nucleus of comet Hartley 2! The flyby was successful, and it took incredible images of the comet’s solid heart:
expoxi_medres_hartley2
Wow! These images are in order of approach (left to right, top to bottom), as EPOXI flew by. We knew from ground-based radar that the nucleus wasn’t round, but these pictures clearly show it to be shaped like a peanut. That’s not too surprising; this shape is common in asteroids and comet nuclei. But what detail! You can see the surface is irregular and contoured. There’s a groove of some sort on the left side, and what might be an impact crater or pit on the very left tip.
And those bright streamers of light? Those are jets of gas shooting away from the comet, formed when frozen material on the comet surface gets heated by the Sun, expands, and shoots away!
Amazing. And very lovely.

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