Comet ISON takes a beautiful picture as Damian Peach’s recent photo attests. Feast your eyes on that Mediterranean-hued coma and long tail. How I wish it looked like that in a telescope. While there’s still much time for the comet to develop into a hoped-for spectacle, it’s looking a little anemic to date. ISON presently glows around magnitude 10 with a brighter false-nucleus (that’s the bright spot in the comet’s head inside of which is the actual comet) and a pretty but faint streak of a tail.
Once the crescent moon disappears from the morning sky later this week, views of the comet will improve. I’ll prepare a chart that telescope owners can use later this week to find it.
Unlike some other comets, which become more active and brighten strongly as they approach the sun, most of ISON’s recent climb in brightness may have more to do with its increasing proximity to Earth and sun. This according to expert comet observer Alan Hale, co-discoverer of Comet Hale-Bopp. Hale calculated that if you subtract the brightness contribution from its decreasing distance, ISON has brightened by only a tenth of magnitude in the past two weeks. That’s piddling.
Comets are composed of about 80-90 percent water ice. Normally, once they cross the “frost line” just outside the orbit of Mars, that ice begins to vaporize with vigor under the solar heat lamp. Since ice carries sunlight-reflecting dust, we would expect a comet like ISON to shoot up in brightness both from vaporizing ice and decreasing distance.
ISON passed the frost line in late August. For whatever reason, it’s lagging, an indication it might be a very small comet. Then again, maybe its icy crust needs a little more time to sunder and blossom. I’ll end my speculations here, since we know all too well that comets are famous for their unpredictability.
Whatever ISON does, the National Science Foundation and Astronomy magazine want you to capture it on camera. The two organizations have teamed up to celebrate Comet ISON’s arrival by sponsoring a photography contest from October through mid-January. Both amateur and professional photographers worldwide can submit images online through January 15, 2014 in three categories:
* Cameras and tripods without the use of tracking or telescopes
* Piggyback cameras riding atop a telescope or motorized mount
* Through-the-scope images where the telescope acts as the camera’s lens
The prizes will easily take care of your car payments for a few months. First prize in each category is $2,500. Second prize is $1,000. In addition to the six prize winners, Web site visitors will choose an additional “People’s Choice” award worth $1,500. Winners will be notified before the public announcement is made in April 2014. Winning images will appear in print in Astronomy magazine and online at Astronomy.com, DiscoverMagazine.com, and on the NSF Web site.