Spaced-Out Challenge: Comet ISON Update

Comet ISON (more formally C/2012 S1) was initially discovered just under a year ago by Vitali Nevski and Artyom Novichonok using the International Scientific Optical Network (hence it's common name) in Russia. When it's initial trajectory and observations were reviewed, some jumped the gun and hinted it could be the "Comet of the Century." This is too bad, as comets are extremely unpredictable: even right now, just ten weeks before it dives within a million miles from the surface of the sun, there is no way to tell if ISON is going to dazzle or disappoint.

So here is what we know about ISON. Amateur observations have begun on the Comet, with it's magnitude currently between +11.5 and +12. It has a nucleus about 3 miles across. Theoretically, using Stellarium or other software, you can hunt it down with a telescope of at least 8" aperture. One dedicated amateur, Wes Stone, did just that last Tuesday, and submitted this rough sketch to the Cloudy Nights ISON thread:

Its low proximity to the horizon and faintness makes it a rough object to confidently locate in the eyepiece right now, so many have stuck with the imaging route to get their first glimpse, like this stacked image by astrophotographer John Wunderlin taken Friday morning:

NASA plans to aim it's Mars Reconnaissance Observer at ISON when it passes close by the red planet October 1st, it's STEREO spacecraft around October 10th, and SOHO on November 27th. Amateur observers and imagers are encouraged to submit their observations here.

Ok enough excuses, CAC. When CAN I see it?
Getting right to the point, an amateur using ablog2.mu.nulescope or very large binocular will be able to catch it by the beginning of October. Any binocular owner should be able to snag this icy phantom by the middle of October. It should continue to brighten as it nears it's perihelion (closest approach to the sun) November 28th, brightening into naked eye view from very dark locations as early as late October, the dark sky sites listed in the directory by the first week of November, and most suburban skies by the final days before perihelion and the first week of December. This is all subject to change of course. It could melt away to nothing, break up, or maybe, just maybe, dazzle everyone with a working pair of eyes right after Thanksgiving. Only time will tell.

Anyways, that's it for this week's short edition. All of the previous threads, including the buyer's guide, urban astronomy tips, and dark sky directory, can be found here. Next week we review the major constellations and stars for Fall, and perhaps a brief discussion of Paul Bogard's excellent work on the vanishing darkness, The End of Night. Until then, clear skies to you and keep looking up!

posted by CAC at 05:06 PM

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