In Fact, It’s Getting More Interesting All the Time

I’ve seen a quote floating around the Internet/WebThing that “comets and cats do as they please”. With respect to C/2012 ISON, that’s very true. This comet, much touted as “the comet of the year” may actually live up to its billing, despite the many folks of my acquaintance who have delighted in calling it a fizzle or worse just because it’s not blazing across the sky–yet.

Today there’s news that Comet ISON could be easily visible from Earth in early December, after its closest approach to the Sun (November 28). Since it’s not very bright now, how can this be?

Here it is straight from the scientist’s mouth (press release, actually):

 “We measured the rotational pole of the nucleus.  The pole indicates that only one side of the comet is being heated by the Sun on its way in until approximately one week before it reaches it closest point to the Sun,” said Planetary Science Institute Research Scientist Jian-Yang Li, who led a team that imaged the comet.

“Since the surface on the dark side of the comet should still retain a large fraction of very volatile materials, the sudden exposure to the strong sunlight when it gets closer to the Sun than Mercury could trigger huge outbursts of material,” Li said.

Dr. Li presented this information at a meeting of the American Astronomical Society’s Division for Planetary Scientists, being held in Denver, Colorado this week.

I think that’s pretty good news and reinforces that the comet is doing just what it wants. All we can do is hang on and wait to see how it survives perihelion in a few weeks.

A lot of other folks aren’t disappointed with ISON, including Adam Block, who used the Mount Lemmon Observatory  to take this great image on October 8, 2013.

If you’re new to the comet game, here’s a little background on Comet ISON.  It was discovered in September 2012. At that time, it was out past the orbit of Jupiter and was showing some activity already. After some observations, astronomers determined that Comet ISON is a sungrazer — that means it will pass very close to the Sun.  As it does, the comet will sublimate its ices as it is heated, and may also release a lot of silicate and metal-rich dust. It’s highly likely that this comet will become much brighter than any other sungrazer as it rounds the Sun.

The other interesting thing about Comet ISON is that it’s on its first trip around the Sun. That means its ices have never been heated (or “processed”). It’s a treasury of information about conditions in the outer solar system — and also about what it was like in the early solar nebula when the comet formed some 4.5 billion years ago.