A team of astronomers announced their first snow Thursday — not due to the approaching winter, but from a spacecraft that observed a peanut-shaped comet spitting fluffy ice balls into space.
The Deep Impact spacecraft, built by Ball Aerospace & Technologies of Boulder, flew within 435 miles of the comet known as Hartley 2 on Nov. 4, snapping images as it whizzed past at about 27,000 mph. Images released that day revealed a nearly 1 1/2-mile-long body with a smooth middle and rough, bulbous edges that was spewing gas from its surface.
Scientists since have noticed the white specks circling the comet, as if it were inside an invisible snow globe. When they analyzed the images, they were in for a surprise — the smooth middle portion, which they expected to be relatively inactive, was emitting water vapor, while the ends released ice chunks, some as large as basketballs.
The flurry of white specks caused the astronomers’ jaws to drop, said Peter Schultz, a team scientist from Brown University, in a news conference in Washington, D.C.
University of Maryland astronomer Michael A’Hearn said he figures that 40 to 50 percent of the comet’s ice was made of frozen carbon dioxide, with the rest made of frozen water.
Dry ice in the comet’s bulbous ends might mean Hartley 2 was formed far out in the solar system, A’Hearn said. But the fact that the middle section appears to lack dry ice might mean this comet was the result of the mixing that occurred as the solar system was coalescing. If so, it could reveal clues about how that early development happened.
