SOHO Sungrazer.

SOHO , the space-based SOlar and Heliospheric Observatory, has become by far the reigning champion facility for discovering comets, its total having recently reached 200 . As might be expected of a solar observatory, most of the SOHO discovered comets are sungrazers , destined to dive within a mere 50 thousand kilometers or so of the solar photosphere . At that range the intense heat and gravitational forces make it unlikely these primitive chunks of ice and dust will survive . Based on their similar orbits, as first worked out by 19th century German astronomer Heinrich Kreutz, all sungrazers are believed to originate from a single large parent comet which broke up during a perihelion passage perhaps 2,000 years ago. Over time, pieces have continued to split off producing a family of smaller comets which seem to travel in the same orbit. These frames from SOHO's coronograph were taken two hours apart on April 29 of this year. They show a sungrazer (SOHO comet discovery number 111 ) with a long, bright tail headed toward its fiery encounter. The sun itself is hidden behind the coronograph's occulting disk at each frame's upper right.