2013: The Year of the Comets: update May 2013
After the Transit of Venus last year, 2013 looked like just a normal year of observing the sky. Two recent comet discoveries changed that. After a number of years without a truly bright naked eye comet, we may get not one but two! Three comets will pass, although only two may be naked eye for us. PanSTARRS, Lemmon, and then the one being hailed as the "Comet of the Century," In March the opening act for the year was Comet C/2011 L4 (PanSTARRS). The comet is currently in the northern hemisphere's sky, although it is now a telescope/photographic view, about magnitude 7 and fading (as of May 1). During the visible period in mid-March, we had poor weather. Only a few nights were clear. Never as bright as advertised, on the night of March 12th it was right next to the very young Moon. Very small in the sky, Pan-STARRS was more of a binocular object than naked eye for us in Tennessee. If you are interested in finding it, a rough finding chart is below, courtesy of Seiichi Yoshida. (www.aerith.net/comet/catalog/2011L4/2011L4.html)
As we move through May, two of this year's comets are visible in photographs...
Comet Lemmon and Comet ISON.
Comet Lemmon (C/2012 F6) has put on a nice show for the southern hemisphere, occasionally captured in the same image as Comet Pan-STARRS. Past perihelion and fading, it has now moved far enough north for our part of the world to see it, except you have to get up early! The nice thing is that it is moving past one of the easiest asterisms in the sky to find: the Great Square of Pegasus. Rising in the predawn sky, the comet begins the month just below and left of the left bottom corner of the Square, and slides along the backside of Pegasus through the month, moving higher and higher in the sky. So if you are awake in the hour and a half before sunrise and have a telescope handy, you might look for the pretty green Comet Lemmon.
You might also want to try for a last (photographic) look at Comet C/2012 S1 (ISON), still in Gemini, as it sinks with that constellation ever nearer the sunset horizon. Vanishing by the end of the month, we'll have to wait until we come around the Sun enough and Gemini rises in the early morning... by September we might start getting an inkling of whether this will truly be a "comet of the century."
Comet ISON (named after the automated telescope program that detected it) promises to brighten to negative magnitudes in the fall of 2013. With luck we will first see it brighten in the predawn skies before Thanksgiving. Then we'll watch it round the Sun, passing just more than a solar diameter from the surface. If ISON survives, it may be an extraordinarily bright comet in our evening sky in December. The hype is already there - "as bright as the full Moon!" Well, we've all been disappointed by comets, so we will just have to wait and see what we get, hoping for the best.