Live – Watch a Comet’s Death Plunge
January 2, 2010 2 Comments
A few thousand years ago a relatively large comet passed extremely close to the Sun. Whether due to the intense heat or gravitational tides, the comet split into a number of pieces. Since that time the cometary pieces have returned and continued to split into smaller and smaller pieces, something known as cascading fragmentation. Some of the fragments are still large enough to produce some of the greatest comet displays in history. The last such display was Comet Ikeya-Seki in 1965. But these large fragments are rare and only appear a few times per century. These comets are now known as the Kreutz family of sungrazing comets.
Since the late 1970s, a number of satellites have been equipped with a solar coronagraph which allows objects to be imaged that are very close to the Sun. Though the coronagraphs were meant to observe the Sun’s outer atmosphere, the corona, they also found many small comets. Currently there are 3 satellites monitoring the area near the Sun, SOHO (Solar Heliospheric Observatory) and STEREO-A and STEREO-B (Solar Terrestrial Relations Observatory). These satellites find hundreds of comets every year. With rare exception, all of the comets are invisible to Earth-based telescopes.
Right now a smaller member of the Kreutz family, sometimes called a pygmy sungrazer, is hurtling towards the Sun. The comet was discovered by Australian amateur Alan Watson on images taken with the STEREO spacecraft. This comet is very small, probably no larger than a few meters across. [Added later: The size estimate of a few meters is for the nucleus. The coma and tail which can be seen in the SOHO images is much, much larger.] It is unlikely that it will survive its close approach to the Sun. In fact, no Kreutz sungrazers discovered by SOHO or STEREO have survived their close passage near the Sun.
Lucky for us, we have a front-row seat as the comet plunges closer to the Sun. SOHO makes their images available to the public in near-real-time. The image below is from a few hours ago and points out the position of the comet, as well as the planets Mercury and Venus.
The most recent image from the C3 camera can be seen at the SOHO website. Movies for the past few days can also be found there. The comet is moving towards the Sun (to the upper right) over the next day. At some point the comet will probably disintegrate and fade from view. This can happen at any moment though the process will occur over many hours so the comet will be seen to fade from frame to frame rather than disappear all at once.
A second camera on SOHO produces image of the region even closer to the Sun. The comet is not yet in this camera’s field of view but may appear in the next few hours assuming it survives till then. Images and movies from this camera (C2) can also be found at the SOHO site.
Currently, the comet is unnamed. It probably won’t receive an official designation and name for a few days.