Comet ISON: What It Is And Isnt

It’s an Inbound Chunk of Ice and Dust

You may have heard there’s a comet coming. Its formal name is C/2012 S1, and its less formal name is Comet ISON. It was first discovered in 2012 by observers using an automated telescope that is part of the International Scientific Optical Network in Russia. Comet ISON is a sungrazer, which means that its orbit will take it very close to the Sun when it reaches perihelion on November 28th of this year. There’s some chance that the comet will break up if it gets too close to the Sun, but that remains to be seen.

Astronomers analyzing the orbit of Comet ISON say that it’s nearly parabolic, which suggests that the comet is on its first trip out from its origin in the Oort Cloud. That makes it particularly fascinating to study since the comet’s nucleus has not been modified by previous passages close to the Sun and thus, its icy materials will be “pristine” (meaning that they will be largely unchanged since they formed some 4.5 billion years ago).

Since Comet ISON is on its first trip around the Sun, we know little about the comet’s icy composition. It’s probably got a significant amount of water ice, mixed with methane or ammonia ices, and some amount of dust. It has already sprouted a tail, and it will likely brighten to at least be seen through binoculars or a small telescope. There’s some chance it could get bright enough to see with the naked eye before and after perihelion (its point of closest approach to the Sun in its orbit). There have been some claims that Comet ISON could look spectacular, but as of right now, it’s not clear if it will brighten enough to be as spectacular as Comet Hale-Bopp was in 1997.  We’ll know more as the comet gets closer to the Sun in the coming months, and I expect to see more images from Hubble, a number of groundbased observatories and possibly even from the Curiosity rover on Mars.

It looks like Comet ISON is doing what all comets do as these chunks of ice and dust follow along their orbits. They brighten up as they approach the Sun. The comet may sprout a plasma tail soon, which is also normal and nothing to get worked up about. I spent some of my time in graduate school studying comets and their plasma tails. They tell us a lot about what’s happening in the solar wind (we often called plasma tails “solar wind socks”), and this year it could be quite interesting to see how our solar max Sun cycle will treat the comet. Other people are more interested in the dust tail, and still others are hoping to learn more about its nucleus and its ices and dust as they sublimate and create the tails. In that respect, Comet ISON is a perfect target to study with instruments that can sense not just visible wavelengths of light, but also ultraviolet and infrared. Those will tell us about the ices in the comet as well as something about the dust component. And, in turn, that knowledge will give astronomers insight into conditions in the solar nebula as the Sun and planets were forming billions of years ago.

It’s Not a Mysterious Spacecraft or Rogue Planet…

Of course, there’s a HUGE whack job contingent out there making all kinds of claims about Comet ISON that are, to put it politely, not supportable by science facts and reality. This happens every time there’s a comet.  It occurred with Hale-Bopp, with Hyakutake, with Comet Halley. In the case of Hale-Bopp, people actually killed themselves due to the wild theories put forth by a cult that had some pretty wacky ideas about the comet.

I don’t know why making up unreal, unscientific stuff about comets is so attractive, but it’s something we all have to put up with from time to time. Mention a new comet and the whack jobs just coming streaming come out of the woodwork. I’m not a psychologist, but I’m guessing that maybe the people who come up with weird unscientific theories about comets are deprived of attention and this is their way of getting it.

Some of them think that Comet ISON is traveling with companions that scientists aren’t talking about. That’s because there ARE no companions to talk about. What these comet nutjobs think are mysterious space ships turn out to be hot pixels in the camera that was used to take the images. There have been many images of the comet taken already, and none of them show these mysterious companions. They show a comet, doing what comets have done since the solar system formed. Think about this: there are thousands of amateurs with good telescopes and cameras out there, taking pictures of the comet. NONE of them have seen anything like what the nutjobs are claiming.

Others claim that the comet is actually headed right at Earth and NASA is hiding that information from us. I find that one particularly amusing since anybody who ever studied a little physics or astronomy (and that includes a lot of high school and college students), can calculate an orbit from the data we already have about the comet and figure out that it will not hit Earth. It won’t even come close.

Yet another bunch is screeching around about how the comet will cause earthquakes. Yeah, okay, that one’s fairly easy to use as  ”PROOF!! PROOF, I TELL YOU, THAT COMETS ARE OUT TO GET US!!! RUN AND HIDE (BUT GIVE US YOUR MONEY, FIRST)!!!!”  That’s because Earth has thousands of quakes each day and any ignorant lout can fake a connection between an earthquake and something else.

Truth is, earthquakes are not caused by little chunks of ice thousands of kilometers away.  I mean, think about it. The comet’s nucleus is quite small—possibly only a kilometer or so across. That’s WAY too small to have much of a gravitational pull on anything in its own vicinity, much less on Earth, which at this point is thousands and thousands of kilometers away from the comet.  You can actually do the math on this and figure it for yourself.

More to the point, the earthquakes Earth does have are due to its being a planet with plate tectonics and crustal motions that are caused by the normal stresses of BEING a rocky planet. There are many factors that go into making earthquakes, but a chunk of ice out in space isn’t one of them.

So, over the next few months, if you see fantastical claims about how the comet caused an earthquake, smile indulgently and don’t take it seriously. Fantastical claims require fantastical evidence, which the comet fanatics aren’t providing. You’re a smart, thinking person; don’t fall for wild claims by nutjobs. Be amused by these fanciful tales because that’s all they are. The real comet and the real universe are so much more fascinating than any conspiracy theory anybody ever dreamed up.