As I write this, a bright comet is headed for oblivion as it dives into the sun this morning. Four independent comet hunters – M. Kusiak, S. Liwo, B. Zhou and Z. Xu – discovered the comet Thursday (Sept. 29) on pictures taken with the Solar Heliospheric Observatory (SOHO) coronagraph, a device that blocks the glare of the sun so astronomers can study its outer atmosphere called the corona. Yesterday the comet looked like a little tadpole of about 4th magnitude “swimming” toward the sun, but by early this morning had bloomed into a brilliant object of about magnitude -1. For comparison, Mercury’s magnitude today is -1.4, similar to the brightest star in the sky, Sirius.
Like Mercury, the comet is bright enough to saturate the electronic detectors in the SOHO camera causing white line artifacts in both, an effect called blooming. If you’ve ever taken a picture of the sun with your cell phone or digital camera, you’ve probably seen similar lines or streaks. The appear when taking pictures of very bright light sources.
Pity that both Mercury and the comet are simply too close to the sun to safely observe with amateur equipment. The glare is fearsome — trust me, I’ve tried! If by chance the comet survives its solar encounter, perhaps it will come around the sun’s other side and appear in the evening sky … but I doubt it.
The new comet is almost certainly a member of the Kreutz (pronounced ‘kroits’) family of comets, the remains of a once much-larger comet that fragmented long ago from stresses induced by solar heating during a close pass. The remaining fragments are named after the 19th century German astronomer who first identified them. Small, 10-15 feet-sized Kreutz chunks are vaporized regularly by the sun during the year, but this is one of the larger pieces, the reason it’s brighter than most.
If you’d like to follow the suicide comet’s progress and make a movie of its headlong path into the sun, please visit the LASCO/EIT Real-Time movie site. Click the button under either C3 (wide field coronagraph) or C3 (narrow). Under File Type select JPG and then press the Submit Query button.
Since I’m ever an optimist, should the comet survive and remain bright enough track after it passes the sun, I’ll make a finder map to help you locate it.
Last night the aurora was once again a ghostly visitor to our northern sky. It played all night just a few degrees above the horizon. If your view was blocked even by distant trees, you might have missed the display. I saw only a pale glow until I parked the car out on a road next to a huge bog with a clear view all the way to the bottom of the northern sky. The changes were slow and subtle but the transformation of the aurora from a mere fringe at the horizon to an active green band as thick as the Dipper Bowl were most enjoyable. More minor auroras are expected tonight and tomorrow night for the northern U.S., Canada and northern Europe.