Saturday, December 29, 2007

Comet Holmes

The most bizarre astronomical sight of 2007 was definitely Comet Holmes. I heard about its outburst on October 25th, which surprised many astronomers. Before that the comet was merely a 16-magnitude spec, dimmer than Pluto, and was dimming every day. It could be seen only through powerful telescopes. Then something unexpected happened. On October 24th, it began to explode into view brightening by 60%(!) every hour!

Having to wait for clear skies, I finally observed in on October 29th. It took me literally a couple of seconds to spot the comet in the constellation of Perseus with my naked eyes! You could tell right away you were not looking at a star - it looked like nothing I've seen before! This is what I saw:

My 8-inch reflector telescope revealed more detail. Fuzzy yellowish coma surrounding the nucleus looked like something out of this world (literally!). It first looked more like a sphere (because of our perspective on the comet's position) so I played with the contrast on the following picture to make out the tail of the comet. You can actually tell the direction of the comet:

At more magnification I saw the comet's inner comma surrounding the nucleus. This my best shot of this incredible spectacle.

Why did such the outburst took place? We may never find out. As we know, comets are icy rocks that are heated by the Sun releasing gases trapped in the ice. The prevailing theory about Comet Holmes' outburst is that the varying warming by the Sun caused a "crust" to form effectively trapping heated gases under that crust. Once the pressure inside grew, the crust broke releasing all this gas at once.

Will we see comet Holmes again? With it's orbital period of less than 7 years it is our neighborhood's frequent guest. However, we are more likely to see it again as a tiny pinpoint. Last time Comet Holmes put up a show like this, it was 115 years ago when it was first discovered by the English astronomer Edwin Holmes. Don't you fell lucky?
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