Alan Boyle writes about a new comet:
A new comet superstar named C/2012 S1 (ISON) is heading for the spotlight starting in November 2013 — but will it perform as some hope it will, or will it be a dud of cosmic proportions?
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That orbit is due to bring Comet ISON incredibly close to the sun — within just 1.1 million miles (1.8 million kilometers) in late November of next year. As a result, current projections suggest it could get very bright. How bright? Various estimates have set the brightest magnitude at -10 to -16. That suggests the comet could become brighter than the full moon — which led Astronomy Magazine's Michael E. Bakich to say it "probably will become the brightest comet anyone alive has ever seen."* * *
Battams said a lot depends on Comet ISON's composition. "It could turn into a huge letdown if it's a comet that's just too fragile and dissipates as it makes its way into the inner solar system," he told me. That's basically what happened to Comet Elenin. Because ISON appears to be a "new" comet coming in from the far-flung Oort cloud, it's tough to predict how the comet will behave.
The comet is currently in the constellation Cancer, as indicated in this star chart from Astronomy Magazine. When the comet hits prime time, a year from now, it should be heading through the constellation Virgo and visible from northern latitudes before sunrise. Here's a night-sky animation from the Remanzacco Observatory that shows how things are likely to go down.
During the months ahead, astronomers of all stripes will be keeping a watch on Comet ISON and refining their expectations. "I would imagine that by next summer, we should have a much better handle on it," Battams said. In the meantime, check out the chatter on SpaceWeather.com, the Remanzacco Observatory's comet blog and the Comets Mailing List. (And on Twitter, keep an eye on @SungrazerComets.)