FLASHBACK:
One year ago today, on Oct. 24, 2007, Comet 17P/Holmes shocked astronomers when it suddenly exploded, brightening a million-fold to naked-eye visibility. Within three days of the blast, the comet was bigger than Jupiter, and within three weeks it was larger than the sun itself. Spanish photographers Vicent Peris and Jose Luis Lamadrid recorded this view on Nov. 1, 2007, using little more than a 7-inch telescope.
What happened to Comet Holmes?
Just-released observations by NASA's Spitzer Space Telescope define the mass and velocity of the explosion: "The energy of the blast was about 1014 joules and the total mass was of order 1010 kg," says Bill Reach of Caltech. In other words, Holmes exploded like 24 kilotons of TNT and ejected 10 million metric tons of dust and gas into space. These numbers fit a model favored by Reach in which a cavern of ice some hundred meters beneath the comet's crust changed phase, from amorphous to crystalline, releasing in transition enough heat to cause Holmes to blow its top.
Holmes has exploded twice in recorded history--in 1892 and 2007.
Two caverns down, how many to go? No one knows. Browse the gallery for a preview of what the next blast might look like:
Comet Holmes Photo Gallery
Posted: 12:04:25 PM
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