New comet may be brighter than full moon by November 2013

This little smudge doesn't look like much now, but it's a newly discovered comet that's heading towards the sun. C/2012 S1, as it's known, will make its closest pass in November of next year, by which point astronomers are predicting that it may appear brighter than a full moon. Much brighter.

A comet appears brighter the closer is gets to the sun, as the dirty ice that it's made of vaporizes and forms a glowing tail pointing away from the sun. The comet itself also glows as it reflects sunlight, putting on a fairly spectacular display. Right now, C/2012 S1 is out around Jupiter, so it's not close enough to the sun to be able to see, but in about a year, it'll be close enough to be seen without a telescope or binoculars.

Astronomers are estimating that at its peak at the end of November 2013, C/2012 S1 may reach a brightness magnitude of -16. For reference, the full moon (the brightest object in the night sky) has a magnitude of -13, and since the scale is logarithmic, C/2012 S1 may be twice as bright. It'll be close to the sun and the horizon, but you should still have no trouble spotting it.

This brightness estimate comes from what we currently know about C/2012 S1, which is that it's likely a new comet that's never been through the inner solar system before, meaning that the sun hasn't had a whack at it yet. So, what may happen is that the comet will get in close to the sun and a layer of ancient ice will melt away, exposing a layer of volatile gasses and dust that could lead to a huge explosion in brightness and a gigantic tail. Maybe. We hope.

Similar predictions were made for a comet named Kohoutek back in 1973 and it more or less utterly failed to meet them, as it was actually a Kuiper-belt object instead of a comet from the Oort cloud, meaning that it was mostly rock instead of mostly ice. But even if C/2012 S1 doesn't reach that -16 magnitude, it should still put on a very good show.

Also, there's another comet scheduled to put on an appearance in 2013: comet C/2011 L4 (PANSTARRS) will make its closest approach to the sun in March of next year. At a maximum magnitude of 1, it'll be visible to the naked eye and brighter than Polaris, but you'll want to get some binoculars or a telescope for the best view.

Via New Scientist and Astronomy Now

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