National Geographic News

Victoria Jaggard

National Geographic News

January 13, 2010

Like a modern-day Icarus, this newfound comet learned the hard way what happens when you fly too close to the sun.

Amateur astronomer Alan Watson discovered the small comet while pouring over pictures taken in December 2009 by NASA's Solar Terrestrial Relations Observatory, or STEREO. (See pictures of the sun taken by spacecraft.)

The space agency's orbiting Solar and Heliospheric Observatory (SOHO) then witnessed the bright, unnamed comet get vaporized on January 3. (Related picture: "Sun Probe Spies New Periodic Comet.")

SOHO was able to watch the comet plunging toward the sun thanks to its occulting disk, seen as an opaque circle at the center of the images. The disk creates an artificial solar eclipse, blocking out direct glare from the sun to reveal the fainter solar corona and surrounding stars, planets, and other objects.

Zooming in from the left, as seen by SOHO, the comet starts to dissolve as it nears the sun, and it never reappears from behind the occulting disk.

Astronomers think the comet must have been one of the so-called Kreutz sungrazers, a family of bright comets with orbits that take them within 50,000 to 300,000 miles (80,470 to 482,800 kilometers) of the sun's surface.

"There were particularly spectacular Kreutz sungrazers in 1843, 1880, and 1882, and again in 1963, 1965, and 1970," comet expert Brian Marsden, director emeritus of the International Astronomical Union's Minor Planet Center, said in an email.

The comets are named after Heinrich Kreutz, a German astronomer who studied the 19th-century sungrazers, Marsden said.

If the comets aren't destroyed outright by their close solar encounters, the Kreutz members can break into smaller fragments that go on to become new sungrazers.

"In 1967 I demonstrated that it was almost certain that the 1882 and 1965 members had broken off from each other at their previous approach to the sun," Marsden said.

And since 1979, sun-watching space missions have been keeping an eye on the latest additions to and subtractions from the Kreutz family.

"SOHO in particular has recorded some 1,500 of them since 1996," Marsden said. "One about this bright appears about once a year."

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