[meteorite-list] SOHO Spots 2000th Comet

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Sun, 2 Jan 2011 15:21:38 -0800 (PST)
Message-ID: <201101022321.p02NLdFO019479_at_zagami.jpl.nasa.gov>

http://www.nasa.gov/mission_pages/soho/comet-2000.html

SOHO Spots 2000th Comet
Karen C. Fox
NASA's Goddard Space Flight Center
December 28, 2010

As people on Earth celebrate the holidays and prepare to ring in the New
Year, an ESA/NASA spacecraft has quietly reached its own milestone: on
December 26, the Solar and Heliospheric Observatory (SOHO) discovered
its 2000th comet.

Drawing on help from citizen scientists around the world, SOHO has
become the single greatest comet finder of all time. This is all the
more impressive since SOHO was not specifically designed to find comets,
but to monitor the sun.

"Since it launched on December 2, 1995 to observe the sun, SOHO has more
than doubled the number of comets for which orbits have been determined
over the last three hundred years," says Joe Gurman, the U.S. project
scientist for SOHO at NASA's Goddard Space Flight Center in Greenbelt, Md.

Of course, it is not SOHO itself that discovers the comets -- that is
the province of the dozens of amateur astronomer volunteers who daily
pore over the fuzzy lights dancing across the pictures produced by
SOHO's LASCO (or Large Angle and Spectrometric Coronagraph) cameras.
Over 70 people representing 18 different countries have helped spot
comets over the last 15 years by searching through the publicly
available SOHO images online.

The 1999th and 2000th comet were both discovered on
December 26 by Michal Kusiak, an astronomy student at Jagiellonian
University in Krakow, Poland. Kusiak found his first SOHO comet in
November 2007 and has since found more than 100.

"There are a lot of people who do it," says Karl Battams who has been in
charge of running the SOHO comet-sighting website since 2003 for the
Naval Research Lab in Washington, where he also does computer processing
for LASCO. "They do it for free, they're extremely thorough, and if it
wasn't for these people, most of this stuff would never see the light of
day."

Battams receives reports from people who think that one of the spots in
SOHO's LASCO images looks to be the correct size and brightness and
headed for the sun - characteristics typical of the comets SOHO finds.
He confirms the finding, gives each comet an unofficial number, and then
sends the information off to the Minor Planet Center in Cambridge, Mass,
which categorizes small astronomical bodies and their orbits.

It took SOHO ten years to spot its first thousand comets, but only five
more to find the next thousand. That's due partly to increased
participation from comet hunters and work done to optimize the images
for comet-sighting, but also due to an unexplained systematic increase
in the number of comets around the sun. Indeed, December alone has seen
an unprecedented 37 new comets spotted so far, a number high enough to
qualify as a "comet storm."

LASCO was not designed primarily to spot comets. The LASCO camera blocks
out the brightest part of the sun in order to better watch emissions in
the sun's much fainter outer atmosphere, or corona. LASCO's comet
finding skills are a natural side effect -- with the sun blocked, it's
also much easier to see dimmer objects such as comets.

"But there is definitely a lot of science that comes with these comets,"
says Battams. "First, now we know there are far more comets in the inner
solar system than we were previously aware of, and that can tell us a
lot about where such things come from and how they're formed originally
and break up. We can tell that a lot of these comets all have a common
origin." Indeed, says Battams, a full 85% of the comets discovered with
LASCO are thought to come from a single group known as the Kreutz
family, believed to be the remnants of a single large comet that broke
up several hundred years ago.

The Kreutz family comets are "sungrazers" - bodies whose orbits approach
so near the Sun that most are vaporized within hours of discovery - but
many of the other LASCO comets boomerang around the sun and return
periodically. One frequent visitor is comet 96P Machholz. Orbiting the
sun approximately every six years, this comet has now been seen by SOHO
three times.

SOHO is a cooperative project between the European Space Agency (ESA)
and NASA. The spacecraft was built in Europe for ESA and equipped with
instruments by teams of scientists in Europe and the USA.

For more information about the SOHO mission, visit:
http://sohowww.nascom.nasa.gov/

Follow SOHO's comet findings more closely at:
http://sungrazer.nrl.navy.mil/ or via Twitter at:
http://twitter.com/SungrazerComets
 
Received on Sun 02 Jan 2011 06:21:38 PM PST