Comet should be a big hit

Utahns are well-situated to witness a mini "War of the Worlds" just before midnight tonight when a device from the probe Deep Impact is set to collide with the black, pickle-shaped Tempel 1 comet in the southwestern skies.

Utah is also well-connected to the deep-space experiment: Deep Impact's assignment is to collect as much data as possible from the resulting explosion, with equipment sealed within a housing designed by Clearfield-based ATK Space Systems.

Weather permitting, residents of the Beehive State will have one of the better viewing opportunities available in the world, though telescopes in orbit and around the Earth will be peering at the collision as well.

Still, Utahns without telescopes probably won't be able to see much, says Patrick Wiggins, a NASA solar system ambassador to Utah. The collision has sparked plenty of interest but might be "underwhelming" to the untrained eye, he said.

Wiggins is hoping that experts are wrong, however, as they were when the comet Shoemaker-Levy No. 9 collided with Jupiter in July 1994.

"We thought it wouldn't be anything, and we were dead on wrong on that. It was so bright," he said. "Secretly, I hope we're wrong about this, too."

Northern Utah skies are expected to be mostly clear tonight, according to the National Weather Service.

The probe's "impactor" is scheduled to hit the comet at 11:52 p.m., and the collision could be bright enough to be visible through binoculars or even the naked eye, although the latter possibility is unlikely, according to the National Aeronautics and Space Administration. To be visible to the naked eye, the collision would have to be of the maximum impact — one that would also create a crater the size of Rice-Eccles Stadium in the 10-mile-wide comet. On the other end of the scale, the crater could be as small as a house.

The resulting images should provide "the most detailed pictures we have ever seen of a comet," said Lindley Johnson, program executive. Scientists expect the impact to spray of plume of debris into space.

Researchers, like those at the Jet Propulsion Laboratory in California, "are all sitting on the edge of their seats," said Rick Grammier, the project manager.

Spotting Tempel 1 without a telescope before the collision could prove almost impossible, although the comet will be considerably brighter at impact. The resulting particle cloud could also make the comet glow for hours afterward, possibly even days.