Comet ISON (C/2012 S1) is getting brighter. How bright it will become is still a hot topic. The Minor Planet Center of the International Astronomical Union (IAU), the organization that publishes predicted brightnesses of a variety of celestial objects — including comets — shows ISON at 7th or 8th magnitude in early November. That’s bright enough to see through binoculars or a small telescope from under a dark sky, and a New Moon on November 3 guarantees that our satellite’s light won’t be a problem.
For complete coverage of Comet ISON, visit www.Astronomy.com/ISON.
On the 1st, ISON rises more than four hours before the Sun and stands 30° above the eastern horizon at the start of morning twilight. It lies in southern Leo the Lion, 12° southwest of 2nd-magnitude Denebola. But the comet will be easier to track down by scanning some 7° south-southeast of magnitude 1.5 Mars. A slim crescent Moon rises more than two hours after ISON.
If you have exceptionally clear skies this morning, you might be able to trace the comet’s tail to Mars. In fact, the comet likely will sport two tails, one of charged particles and the other primarily made of dust.
With each passing day, the comet shines a little brighter, rises a few minutes later, and slips slightly lower as morning twilight starts to paint the sky. During November’s first week, ISON should brighten by a full magnitude, appearing 2.5 times brighter than on the month’s first morning.