A comet's final day

While we can't see it from Oneonta today because of the clouds, comet C/2011 W3 (Lovejoy) is putting on a remarkable, unexpected show. Discovered last month as a large fragment of a comet that broke up, its orbit is taking it on what appears to be a suicide mission, plunging it deep into the Sun's atmosphere. This close approach will likely lead to the demise of the comet.

Comets are visitors from the outer regions of the solar system and are comprised of mostly ice and dust. Ranging in size from about 100 meters to nearly 50 kilometers, these objects are often referred to as "dirty snowballs." As it approaches the Sun, a comet's surface begins to vaporize, releasing a trail of dust and gas that streams out behind it as it flies through space. Often there exist two such tails, one of dust which basically follows the orbital trajectory traced out by the comet's motion, and another consisting of ionic gas which is pushed radially outward away from the Sun by the solar wind.

As Comet Lovejoy approaches the Sun, its vaporization causes it to grow brighter over time. Current predictions are that it may grow bright enough to see with the naked eye just after sunset today, provided that you have a clear view of the horizon. But look fast! If you miss it today, it'll be gone tomorrow.

For a consistently updated (often hourly) description as the situation changes, follow this blog here: SOHO and STEREO Sungrazing Comets.