[meteorite-list] SOHO Discovers Its 1500th Comet

[Ron Baalke]

http://www.esa.int/esaCP/SEMB94SHKHF_index_0.html

SOHO discovers its 1500th comet
European Space Agency 
27 June 2008

The ESA/NASA SOHO spacecraft has just discovered its 1500th comet,
making it more successful than all other comet discoverers throughout
history put together. Not bad for a spacecraft that was designed as a
solar physics mission.
 
SOHO's record-breaking discovery was made late on 25 June. When it comes
to comet catching, the SOlar and Heliospheric Observatory has one big
advantage over everybody else: its location. Situated between the Sun
and Earth, it has a privileged view of a region of space that can rarely
be seen from Earth. From the surface, we can see regions close to the
Sun clearly only during an eclipse.  
 
Roughly 85% of SOHO discoveries are fragments from a once-great comet
that split apart in a death plunge around the Sun, probably many
centuries ago. The fragments are known as the Kreutz group and now pass
within 1.5 million km of the Sun's surface when they return from deep
space.

At this proximity, which is a near miss in celestial terms, most of the
fragments are finally destroyed, evaporated by the Sun's fearsome
radiation - within sight of SOHO's electronic eyes. The images are
captured by the Large Angle and Spectrometric Coronograph (LASCO), one
of 12 instruments on board.
 
Of course, LASCO itself does not make the detections; that task falls to
an open group of highly-skilled volunteers who scan the data as soon as
it is downloaded to Earth. Once SOHO transmits to Earth, the data can be
on the Internet and ready for analysis within 15 minutes.

Enthusiasts from all over the world look at each individual image for a
tiny moving speck that could be a comet. When someone believes they have
found one, they submit their results to Karl Battams at the Naval
Research Laboratory, Washington DC, who checks all of SOHO’s findings
before submitting them to the Minor Planet Center, where the comet is
catalogued and its orbit calculated.
 
The wealth of comet information has value beyond mere classification.
"This is allowing us to see how comets die," says Battams. When a comet
constantly circles the Sun, it loses a little more ice each time, until
it eventually falls to pieces, leaving a long trail of fragments. Thanks
to SOHO, astronomers now have a plethora of images showing this process.
"It's a unique data set and could not have been achieved in any other
way," says Battams.

All this is on top of the extraordinary revelations that SOHO has
provided over the 13 years it has been in space, observing the Sun and
the near-Sun environment. "Catching the enormous total of comets has
been an unplanned bonus," says Bernhard Fleck, ESA SOHO Project Scientist.
 
 
Notes for Editors:
 
Anyone can help to search for SOHO’s comets by visiting the Sungrazing
comets page <http://ares.nrl.navy.mil/sungrazer>.

The Minor Planet Center operates under the auspices of the International
Astronomical Union, and is located in Cambridge, Massachusetts.
 
 
For more information:
 
Karl Battams, Naval Research Laboratory, USA
Email: Karl.Battams @ nrl.navy.mil

Bernhard Fleck, ESA SOHO Project Scientist
Email: Bfleck @ esa.nascom.nasa.gov