Most successful comet discoverer in history finds its 1500th comet

Paris, June 28 : The ESA/NASA SOHO spacecraft has just discovered its 1500th comet, making it the most successful comet discoverer in history.

SOHO's record-breaking discovery was made on 25 June.

US-based veteran comet hunter and amateur astronomer Rob Matson discovered the small and faint Kreutz-group comet.

Kreutz-group comets, or sungrazing comets have been observed for many hundreds of years. They travel very close to the Sun, with perihelion distance less than 0.01 Astronomical Units (the mean distance between the Earth and the Sun), or some 1460000 km.

The SOHO (SOlar and Heliospheric Observatory) spacecraft has been able to spot a large number of comets because of 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.

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 SOHO.

Once SOHO transmits to Earth, the data can be on the Internet and ready for analysis within 15 minutes.

The wealth of comet information has value beyond mere classification.

According to Karl Battams from the Naval Research Laboratory, Washington DC, who checks all of SOHO's findings, "This is allowing us to see how comets die."

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," said Battams.

ANI