Archive for Wednesday, July 6, 2005

Telescopes analyze comet collision

July 6, 2005


— The collision of a NASA space probe and a potato-shaped comet hurled a bright cloud of debris into space at the speed of a jetliner, scientists said Tuesday.

The Hubble Space Telescope took a series of pictures of the July 4 impact that initially showed comet Tempel 1 as a fuzzy dot that grew four times brighter 15 minutes after the collision. The fan-shaped cloud flew outward at about 500 mph.

"This is pretty dramatic," said Paul Feldman, a professor of astronomy and physics at Johns Hopkins University, who observed the impact with the Hubble telescope.

The Hubble findings were among observations pouring in from telescopes in space and on the ground. For example, an infrared camera on the Very Large Telescope in Chile detected a color change in the plume, suggesting different-size dust particles were sprayed from the comet.

During the weekend, an 820-pound copper "impactor" separated from NASA's Deep Impact spacecraft, and guided itself into Tempel 1 in a crash that gave off energy equal to detonating nearly 5 tons of TNT.

The impact caused a bright flash of light, then a larger one as a plume of debris spilled from the comet's belly thousands of miles into space. This suggests the probe struck a surface that was soft and powdery before penetrating trapped gas and ice beneath, said Pete Schultz, a Deep Impact co-investigator.

But other researchers said initial ultraviolet readings taken by NASA's Swift satellite detected a dramatic rise in UV light - indicating the surface was hard or there was solid material underneath.

The impact was visible to sky-watchers with telescopes in the western U.S. and Latin America. Astronomers say people with telescopes around the globe may be able to see the comet in the coming nights because of the bright debris plume.


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