AP News, November 17th, 2007
If you haven't seen the mysteriously large comet prominent in the sky in recent weeks, better look soon, astronomers say. The erupting body and its expanding cosmic dust cloud will soon be overshadowed by a commonplace full moon.
Comet 17P/Holmes, once so faint that it was lost by astronomers for half a century, began shooting out gas and dust in such volume three weeks ago that it can be seen with the naked eye. It's increased in brightness by as much as 1 million times.
But the comet's unusual and not quite understood outburst, which happened twice in 1892 but not since, is decreasing ever so slightly. And the moon is getting fuller and brighter, so that will make the comet harder to see.
Johns Hopkins University planetary astronomer Hal Weaver, who took pictures of the October outburst using the Hubble Space Telescope, sent out a piece of advice in an e-mail to his friends Friday: Look for the comet in the northeastern part of the sky in the constellation Perseus in the early evening.
"But do it soon because the moon is becoming more and more of a problem!" Weaver's e-mail warned.
Comet Holmes, which is more than 148 million miles from Earth, was first seen more than 100 years ago and it returned every seven years, albeit faintly. It was so "nondescript that it was lost" in the early 1900s but reappeared in 1964, said Harvard Smithsonian senior astronomer Brian Marsden, who helped find it.
Recently, its cosmic fireworks have had amateur and professional astronomers buzzing.
"This is by far the biggest outburst of this or any other comet," Marsden said.
Weaver said it's gone from "boring" to "spectacular."
Astronomers theorize that when it went around the sun a few months ago, an internal crack formed from heat from the sun and pressure inside that released the gases and dust, Marsden said. But it's still somewhat of a mystery, he said.
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On the Net:
The Hubble Space Telescope page on Comet 17P/Holmes:
http://www.spacetelescope.org/news/html/heic0718.html
