[meteorite-list] Comet surprise makes it visible to naked eye

From: Sterling K. Webb <sterling_k_webb_at_meteoritecentral.com>
Date: Tue, 6 Nov 2007 00:49:44 -0600
Message-ID: <091301c82041$374a7a10$c944e146_at_ATARIENGINE>

Hi, All,

    A good frosty cold front today, superclear skies, and
Comet Holmes just keeps getting bigger and bigger, more
obvious to the naked eye all the time. As a naked eye object,
it's about half the size of the Full Moon. In the 7-degree field
of my 7x50's, it looks like a gigantic dandelion seedhead.
It's hard to assign a magnitude to an extended object, but
I would say it's wonderfully BRIGHT.

Very little visible internal detail, background stars easily visible
through its delicate veil -- it's hard not to just regard it as an
aesthetic object, a giant geometrical abstract sculpture of light.
Sometimes the universe just wants to do a big gee-whiz-golly
object for us.

Here's pages and pages of pictures of Comet Holmes:
http://spaceweather.com/comets/gallery_holmes_page8.htm
That links you to page eight of thumbnails; there's a fine
shot by Ginger Mayfield if you scroll down. It's fascinating
how many different ways astrophotographers have found
of bringing out different aspects of the comet (since no one
photo can show them all).

A very clear and legible map that shows the path of Comet
Holmes as it makes its retrograde loop through Perseus
http://lunarplanner.com/Snippets/snippet.07.11.01-CometHolmes.html
(Even if the website is junk, the chart is well-done.)

The comet is heading for a close pass of Mirphak or Mirfaq
or whatever (alpha Persei). If I had the software, I could see
if the coma will "cover" the star or not (and the date, in
another week or so), but no way to know how big the coma
will be in a week.

On January 22, 2008, it will pass very near to Algol (beta
Persei), and if it still has a big fluffy coma then, we will
get a view of a bright "named" star through the coma.
A prescient individual might take a spectra of Algol before
and during this event and by subtraction, have a transmission
spectrum of the coma.

The comet does have a tail now, and inner and outer coma,
a nucleus, a bright jet, and all the usual features of a comet,
but the tail is angled away so we look at it on a 17-degree off-axis
line of sight, and the fine details are impossible without a really
big 'scope and good seeing. Here's a picture that shows all:
http://datastore.astrofoto.es/holmesmax.jpg
(Being 2000+ meters up in the mountains helps, too...)

Beautiful comet. Given its unique appearance and its unique
behavior, it would be ridiculous to try and apply the "usual"
rules of comet behavior (if there are any) to this one! So, who
knows what a week or a month or more will bring? Nobody
really. I hope it just keeps on growing and surprises us all.


Sterling K. Webb
-----------------------------------------------------------------------
----- Original Message -----
From: "Jason Utas" <meteoritekid at gmail.com>
To: "Meteorite-list" <meteorite-list at meteoritecentral.com>
Sent: Monday, November 05, 2007 8:09 PM
Subject: [meteorite-list] Comet surprise makes it visible to naked eye


http://www.cnn.com/2007/TECH/space/11/05/brighter.comet.ap/index.html

KNOXVILLE, Tennessee (AP) -- 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.

[image]
Comet 17P/Holmes is seen among the stars of the constellation Perseus
in the North-Eastern sky.

 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.

"This is truly a celestial surprise," Lewis said. "Absolutely amazing."

Until October 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.

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.

"What comets do when they are near the sun is very unpredictable,"
Lewis said. "We expect to see a coma cloud and a tail, but this is
more like an explosion, and we are seeing the bubble of gas and dust
as it expands away from the center of the blast."

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. E-mail to a friend

Copyright 2007 The Associated Press. All rights reserved.This material
may not be published, broadcast, rewritten, or redistributed.
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Received on Tue 06 Nov 2007 01:49:44 AM PST