Another Kamikaze Comet

Credit : SOHO

Sundiving comets—a.k.a. "sungrazers"—are nothing new.

SOHO typically sees one every few days, plunging inward and disintegrating as solar heat sublimes its volatile ices.

Yesterday another sungrazer comet gave us an excellent opportunity to see a good show

click to see movie

SOHO excels at this kind of work. The spacecraft's coronagraph uses an opaque disk to block the glare of the sun like an artificial eclipse, revealing faint objects that no Earth-bound telescope could possibly see.

Every day, amateur astronomers from around the world scrutinize the images in search of new comets. Since SOHO was launched in 1996, more than 2000 comets have been found in this way, an all-time record for any astronomer or space mission.

These sungrazers are all related to one another. Astronomers call them the "Kreutz family" after the 19th century astronomer Heinrich Kreutz who first studied them as a group. Modern thinking about the family is attributed to Brian Marsden (1937-2010) of the Harvard Minor Planet Center.

He analyzed the orbits of Kreutz comets and saw that they probably came from the breakup of a single giant comet in the 12th century, probably the Great Comet of 1106. According to Marsden's work, Ikeya-Seki-class comets and the smaller SOHO sungrazers are just different-sized fragments of that one progenitor. 

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