[meteorite-list] The Great Comet of 2007: Watch it on the Web

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Fri, 12 Jan 2007 09:26:40 -0800 (PST)
Message-ID: <200701121726.JAA07371_at_zagami.jpl.nasa.gov>

http://space.com/spacewatch/070112_ns_comet_mcnaught.html

The Great Comet of 2007: Watch it on the Web
By Joe Rao
space.com
12 January 2007

Comet McNaught, the brightest comet to appear in our skies in more
than 30 years, has been putting on a spectacular show in the eastern
sky at dawn and the western sky at dusk this week.

And this weekend it might become even more brilliant.

Ironically, the comet has also been a source of frustration for many
skywatchers, because of its very low altitude. More often than not, the
comet has been hidden either by clouds near the horizon, or nearby trees
or buildings. For this reason, even some veteran observers have been
stymied in their efforts to catch a glimpse of it [images
<http://www.space.com/php/multimedia/imagegallery/igviewer.php?imgid=4539&gid=325&index=0>].

But Comet McNaught is now also visible to armchair astronomers via
images posted to the Internet
<http://www.space.com/spacewatch/soho_lasco_c3_live.html> from the Solar
and Heliospheric Observatory (SOHO) spacecraft. And beginning next
week, it will head rapidly south and likely become a spectacle for
skywatchers in the Southern Hemisphere.

Summer find

The comet was discovered by astronomer Robert H. McNaught Aug. 7 at
Siding Spring Observatory, near Coonabarabran, New South Wales, Australia.

McNaught discovered this comet when it was a few degrees east of the
"head" of Scorpius, on CCD images obtained with the observatory's
Uppsala Schmidt telescope. The images had been obtained as part of the
Siding Spring Survey, whose mission is to contribute to the inventory of
potentially hazardous asteroids (PHAs) and comets (PHOs) that may pose a
threat of impact and thus harm to civilization.

McNaught described the comet - the 31st to bear his name - as magnitude
17.3 - or about 25,000 times dimmer than the faintest object that human
eyes can perceive without any optical aid.

When Brian Marsden at the Smithsonian Observatory in Cambridge,
Massachusetts first calculated the orbit of Comet McNaught (now
catalogued as C/2006 P1) on Aug. 8, it was based on only a handful of
observations. As a result, this first computation suggested that the
comet would come closest to the Sun (called "perihelion") in June 2007,
and then not get much closer than about 145 million miles (233 million
kilometers), or about the distance of the planet Mars.

As more observations of the comet arrived, however, Marsden refined its
orbit, and on Aug. 11, he announced that it was likely to pass well
within the Earth's orbit - a distance of just 15.9 million miles (25.6
million kilometers) - today. That's well within the orbit of Mercury.
This would make the comet much brighter than most, but as a caveat, also
potentially hide it in the Sun's glare.

Mcnaught blossoms

>From August into early November the comet steadily increased in
brightness, but not enough to prevent it becoming lost in the evening
twilight by mid-November.
Received on Fri 12 Jan 2007 12:26:40 PM PST