Most of the sky’s events are as predictable as night and day. But when Comet ISON swings around the sun in late November, amateurs and professionals alike will be watching in anticipation. Estimates of its peak brightness vary by a factor of a million!
At the low end, Comet ISON could be difficult to spot from light-polluted locations. If it hits the high end of the range, though, the comet could be visible in broad daylight for a few hours around 1:40 p.m. EST Nov. 28, looking like a fuzzy dot or dagger.
Warning: It will be relatively close to the sun, so look for it from a location where the sun itself is blocked, and never point binoculars or a telescope near the sun without a professional-grade light filter.
The night spectacle is much simpler, although dark skies and an unobstructed horizon are essential. Try to spot the comet low in the southeast around 5 a.m. local time on Nov. 17 or 18, when it passes near the bright star Spica.
After that, the comet will be too close to the sun to be visible, but it reemerges around Dec. 5. See for yourself what it is doing. Did it survive its closest approach to the sun intact?
If so, it should now have a distinct tail. By Dec. 10 that tail could stretch a quarter of the way across the sky. Then Comet ISON will begin to fade: Watch as it retreats from the sun, back into the void from where it came.