June 26, 2005

View of Comet-Busting Space Show Limited

Amateur astronomers with backyard telescopes and skywatchers at observatories should have a chance to witness the Fourth of July comet collision - if they live in a southwestern swath of the Western Hemisphere.

In the United States, people who live west of a line that extends from Chicago to Atlanta will be treated to a cosmic spectacle when the Deep Impact spacecraft sends a probe crashing into a comet shortly before 2 a.m. EDT on July 4. The farther southwest one lives, the better the view. Residents of the East Coast and upper Midwest are out of luck because the comet will sit below the horizon on impact day.

People in western Canada, Mexico, Latin America and the South American countries of Ecuador and parts of Chile will also see the impact, said Kelly Beatty, executive editor of Sky & Telescope magazine. It will be daylight in the Eastern Hemisphere so the comet will not be visible there.

Professional astronomers from dozens of observatories in 20 countries will watch the impact, although not all will open to the public.

Several observatories plan to have special public viewing hours, including the W.M. Keck Observatory in Hawaii, where people can go behind the scenes and watch astronomers at work. At the Lowell Observatory in Flagstaff, Ariz., visitors can view the impact on a first-come, first-served basis. The Kitt Peak National Observatory, south of Tucson, plans to hold a reservation-only viewing that will include a cookout and comet lectures.

It's unclear whether people might be able to see the impact with the naked eye. Some scientists believe that if the copper probe hits the comet in the right spot, the collision could create a huge debris cloud that may increase the comet's brilliance up to 40 times brighter than normal, possibly allowing people to see the historic event without a telescope.

The plume of debris is expected to linger in the sky for days so those who miss it on impact day will get a second chance the next night if the sky is clear, Beatty said.


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