[meteorite-list] COMET HOLMES LONG LIVED?

[Sterling K. Webb]

http://www.space.com/spacewatch/071026-comet-holmes-update.html

Dramatic Comet Outburst Could Last Weeks 
By Robert Roy Britt
Senior Science Writer
posted: 26 October 2007
02:09 pm ET


A comet that suddenly brightened earlier this week 
has astronomers around the globe fascinated. And 
the show could go on for some time.

Comet Holmes, discovered in 1892, had in recent 
years been visible only through telescopes until a 
dramatic outburst made it visible to the naked eye. 
In fewer than 24 hours, it brightened by a factor 
of nearly 400,000.

It has now brightened by a factor of a million times 
what it was before the outburst, a change "absolutely 
unprecedented in the annals of cometary astronomy," 
said Joe Rao, SPACE.com's Skywatching Columnist. 
The comet is now rivaling some of the brighter stars 
in the sky. Anyone with a map should be able to spot 
it now. 

But Comet Holmes lacks a tail, so it's more like a fuzzy, 
yellow star, observers report. The view is improved 
with a small telescope. 

"This is a terrific outburst," said Brian Marsden, 
director emeritus of the Minor Planet Center, which 
tracks known comets and asteroids. "And since 
it doesn't have a tail right now, some observers 
have confused it with a nova. We've had at least 
two reports of a new star."

The comet could fade in a matter of days or weeks, 
according to a statement from the Harvard-Smithsonian 
Center for Astrophysics.

Comet expert John Bortle expects the comet to continue 
as a naked-eye object for the next few weeks as it dims 
gradually. Bortle said the coma, or fuzzy head of the 
comet, could expand as weeks go by. The coma could 
reach the apparent size of the moon in the sky, he said. 

The comet is located among the stars of the constellation 
Perseus, which is about halfway up in the northeast sky 
in the evening. Perseus is almost directly overhead by 
around 2 a.m. local daylight time and remains well up 
in the northwest at dawn. 

"The comet was plainly visible, disturbing the normal 
pattern of stars that make up Perseus," Rao said after 
observiing it last night. 

The comet orbits the Sun once every seven years at 
a distance of about 200 million miles (compared to 
Earth's 93-million-mile orbit). It was re-observed in 
1899 and 1906 before being lost for nearly six decades. 
Based on a prediction by Marsden, the comet was 
found again in 1964.

"Since then, it's been behaving well-until now," 
Marsden said. Astronomers don't know why the 
outburst occurred.