NASA/JPL-Caltech/UMD/Brown University

ScienceShot: Comet Hartley 2 Spewing 'Cosmic Snowstorm'

Once scientists had a chance to deblur the images they took 2 weeks ago as NASA's EPOXI spacecraft sped by comet Hartley 2, they had a cosmic snowstorm on their hands. Pictures released today reveal giant fluffy flakes of water ice the size of golf balls and even basketballs. The source: Jets of carbon dioxide from warming dry ice are blasting ice particles and dust from either end of the comet nucleus (the brightness streaming from right to left in the image). At the same time, water vapor is gushing from a subsurface store of ice in the nucleus's midsection. The abundant carbon dioxide hints that Hartley 2 formed especially far from the sun in the nascent solar system, but team members haven't a clue what created the comet's dumbbell-like shape with dry ice at either end

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