What is Comet ISON?
Comet ISON is an approaching comet with the potential to put on a stunning show in late 2013. It’s a type of comet known as a “sungrazer,” which means its orbit will bring it close to the Sun -- specifically,within 800,000 miles (1.2 million km) of the Sun’s surface. As the comet’s ice and volatiles react to the heat of the Sun, it could develop a long tail and brighten to the point where it can be seen with the naked eye.
A different sungrazer, Comet Lovejoy, over Santiago de Chile in 2011 Credit: ESO/Yuri Beletsky
Did you say, “potential?” What do you mean, “could?”
It’s difficult to judge at this point whether Comet ISON will be an impressive sight or fizzle out. There are many factors in play. Pros: the comet was bright enough to be discovered when it was quite far away (almost seven times the distance from the Earth to the Sun), it comes from a place that tends to give birth to brilliant comets, and its orbit will bring it near enough the Sun to create a spectacle. Cons: Comets are unpredictable, this one has already failed to brighten as ...