[meteorite-list] Comet C/2012 S1 (ISON): Super-Comet or Super-Dud?

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Tue, 25 Sep 2012 12:26:27 -0700 (PDT)
Message-ID: <201209251926.q8PJQRid024925_at_zagami.jpl.nasa.gov>

http://cosmiclog.nbcnews.com/_news/2012/09/25/14096323-super-comet-or-super-dud-well-see?lite

Super-comet or super-dud? We'll see
By Alan Boyle
Cosmic Blog
September 25, 2012

A new comet superstar named C/2012 S1 (ISON) is heading for the
spotlight starting in November 2013 - but will it perform as some hope
it will, or will it be a dud of cosmic proportions?

"This is one to watch, definitely," said Karl Battams, a scientist at
the Naval Research Laboratory who monitors comets for the NASA-supported
Sungrazer Comet Project <http://sungrazer.nrl.navy.mil/>. "But the
astronomy community in general tries not to overhype these things.
Potentially it will be amazing. Potentially it will be a huge dud."

Comet ISON quickly rose to the top of the charts after its discovery,
which was based on imagery collected on Friday by the International
Scientific Optical Network's
<http://lfvn.astronomer.ru/report/0000029/index.htm> 16-inch (0.4-meter)
Santel reflecting telescope in Russia. The comet, which was described in
an IAU circular
<http://www.cbat.eps.harvard.edu/iau/cbet/003200/CBET003238.txt> on
Monday, takes its common name from the network's acronym. Since the
discovery, astronomers have gone back through their files to find
"pre-discovery" images and calculate the comet's orbit.

That orbit is due to bring Comet ISON incredibly close to the sun -
within just 1.1 million miles (1.8 million kilometers) in late November
of next year. As a result, current projections suggest it could get very
bright. How bright? Various estimates have set the brightest magnitude
at -10 to -16. That suggests the comet could become brighter than the
full moon - which led Astronomy Magazine's Michael E. Bakich to say it
"probably will become the brightest comet anyone alive has ever seen."

Over the next year, you're going to hear a lot of comparisons to
stunners of the past, as long ago as the Great Comet of 1680
<http://en.wikipedia.org/wiki/Great_Comet_of_1680> and as recent as the
Great Comet of 2007 <http://en.wikipedia.org/wiki/C/2006_P1>. You'll
also hear comparisons to past letdowns, ranging from Comet Kohoutek
<http://en.wikipedia.org/wiki/Comet_Kohoutek> to Comet Elenin
<http://www.msnbc.msn.com/id/44555050/ns/technology_and_science-space/t/doomsday-comet-fades-away/>.
You may also hear a fresh wave of doomsday talk, like the ridiculous
rumblings that accompanied Elenin's approach
<http://www.msnbc.msn.com/id/45050612/ns/technology_and_science-space/t/comet-elenin-dead-along-doomsday-predictions/>.

Don't believe anything you hear about a comet catastrophe - and don't
get your hopes up just yet for a comet extravaganza. But do make plans
to keep an eye on the sky in late 2013.

Battams said a lot depends on Comet ISON's composition. "It could turn
into a huge letdown if it's a comet that's just too fragile and
dissipates as it makes its way into the inner solar system," he told me.
That's basically what happened to Comet Elenin. Because ISON appears to
be a "new" comet coming in from the far-flung Oort cloud, it's tough to
predict how the comet will behave.

The comet is currently in the constellation Cancer, as indicated in this
star chart from Astronomy Magazine. When the comet hits prime time, a
year from now, it should be heading through the constellation Virgo and
visible from northern latitudes before sunrise. Here's a night-sky
animation <http://www.fototime.com/95413C237AB9209/convx264.mp4> from
the Remanzacco Observatory that shows how things are likely to go down.

During the months ahead, astronomers of all stripes will be keeping a
watch on Comet ISON and refining their expectations. "I would imagine
that by next summer, we should have a much better handle on it," Battams
said.
Received on Tue 25 Sep 2012 03:26:27 PM PDT