Monday, November 05, 2007

Bright Comet Appears in Perseus

A bright comet has appeared in Perseus, and the reason for its brightness is the fact that it seems to be exploding as it gets closer to the Sun. Yahoo News AP wire excerpt:

KNOXVILLE, Tenn. - A comet that unexpectedly brightened in the last couple of weeks and is now visible to the naked eye is attracting professional and amateur interest.

Paul Lewis, director of astronomy outreach at the University of Tennessee, is drawing students to the roof of the Nielsen Physics Building for special viewings of Comet 17P/Holmes.

The comet is exploding and its coma, a cloud of gas and dust illuminated by the sun, has grown to be bigger than the planet Jupiter. The comet lacks the tail usually associated with such celestial bodies but can be seen in the northern sky, in the constellation Perseus, as a fuzzy spot of light about as bright as the stars in the Big Dipper.

Until Oct. 23, the comet had been visible to modern astronomers only with a telescope, but that night it suddenly erupted and expanded. A similar burst in 1892 led to the comet's discovery by Edwin Holmes.

"This is a once-in-a-lifetime event to witness, along the lines of when Comet Shoemaker-Levy 9 smashed into Jupiter back in 1994," Lewis said.

I witnessed that event, and that description is accurate. Jupiter had several dark spots in its extensive cloud decks that were easily visible in my 8-inch f/5 Dobsonian reflector at 67X.

Scientists speculate the comet has exploded because there are sinkholes in its nucleus, giving it a honeycomb-like structure. The collapse exposed comet ice to the sun, which transformed the ice into gas.

Experts aren't sure how long the comet's show will last but estimate it could be weeks if not months. Using a telescope or binoculars help bring the comet's details into view, they said

I just came inside after having viewed this object for about an hour. The geniuses who wrote this report forgot to mention the exact location within Perseus to look. Maybe they figured that those who wanted to know would simply find a way. Well, here's my helping hand: The comet looks like a fuzzy spot about two degrees east of Mirfak, the brightest star in Perseus (at second magnitude, it is about as bright as Polaris, the North Star). It glows at about third magnitude, and to the unaided eye looks a lot like the famous globular cluster, Omega Centauri (oh how I miss those deep southern skies!). Through my 10x50 binoculars, the fuzziness takes on some granular detail.

Right now the comet is at about 40 degrees above the northeast horizon, and, since Mirfak is circumpolar from where I sit typing this, that means that this comet will be visible all night long. It will appear to reach the zenith, as a result of Earth's rotation, at about midnight. Needless to say that this baby bears watching, and you can bet that I'll be out there as long as the nights are clear.

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