New ‘Sun-Skirting’ Comet Could Provide Dazzling Display in 2013

by Nancy Atkinson on September 25, 2012

Want to stay on top of all the space news? Follow @universetoday on Twitter

2013 is looking to be a promising year for potential naked-eye comets, as a new comet has been discovered that will likely skirt close to the Sun, and could provide a stunning display late next year. The comet, named Comet C/2012 S1 (ISON), as it was discovered by a Russian team at the International Scientific Optical Network (ISON), is currently about the distance of Jupiter’s orbit. But it is projected to come within less than 2 million km from the Sun at perihelion by November 28, 2013. Ernesto Guido and Giovanni Sostero from the Remanzacco Observatory in Italy, along with their colleague Nick Howes from the UK have imaged the comet with the RAS telescope in New Mexico, and say, “According to its orbit, this comet might become a naked-eye object in the period November 2013 – January 2014. And it might reach a negative magnitude at the end of November 2013.”

This new comet joins Comet C/2011 L4 PanSTARRS, which is projected to come within 45 million kilometers (28 million miles) of the Sun on March 9, 2013, which is close enough for quite a bit of cometary ice to vaporize and form a bright coma and tail. Comet PanSTARRS will be visible at perihelion to southern hemisphere, while Comet ISON should be visible to mid-latitude northern hemisphere skywatchers, according to the Remanzacco team.

Orbit diagram from JPL’s Small Body Database of Comet ISON, as of Sept. 25, 2012. Credit: JPL

Right now, Comet ISON is at magnitude +18, and only larger telescopes can see it. How bright will the comet get, and could it even be visible during daytime? That’s the big question which only time will answer. Just 2 million km distant from the Sun is incredibly close, and if the comet stays intact, some estimates say it could reach a brilliant negative magnitude of between -11 and -16. Comparatively, the full Moon is about magnitude -12.7.

But this will happen only if the comet will stay together. Comets can be fairly unpredictable, and other comets that have come that close to the Sun — such as Comet Elenin in 2011, Comet LINEAR in 1999 and Comet Kohoutek in 1973 — failed to live up to expectations of brightness and visibility.

But other comets have survived, like Comet Lovejoy earlier this year, which came two times closer, and Comet McNaught in 2007 which became visible even in daylight when it reached magnitude -5.5. It was not as close to the Sun as Comet ISON will be, however, as McNaught was about 24 million km away.

The discovery of C/2012 S1 (ISON) was made by Vitali Nevski, of Vitebsk, Belarus, and Artyom Novichonok, of Kondopoga, Russia with a 0.4-meter reflecting telescope near Kislovodsk, Russia.

You can see the ephermides of the Comet ISON here, from the Minor Planet Center.

The a Remanzacco Observatory team has more images, including an animation of Comet ISON on their website.

You can see the full visibility calculations of Comet ISON done by Daniel Fischer here.

About 

Nancy Atkinson is Universe Today's Senior Editor. She also is the host of the NASA Lunar Science Institute podcast and works with Astronomy Cast. Nancy is also a NASA/JPL Solar System Ambassador.

SJStar September 25, 2012 at 6:57 PM

A cautionary tale for the blithering blind media, Ms. Atkinson et al. …

Remember the failed Comet Kohoutek in 1973? The media hyped it up and is was visually a dismal failure. It is probably the comet that damaged all visual or public astronomy reputation for many decades. It was reported as the “Comet of the Century!” — ?10 magnitude they said! Absolute piffle! It wasn’t. It was a dud. Yet it too had a close approach at 0.14 AU. It too had a similar inclination and distance.

So before you wind us up like a cheap watch, wait until about August 2013 before madly rabbiting on about it possible brilliance. It is promising, if it fails, we’ll remind you of your follies and expose anyone who does head the warning. Those who damage astronomy by untoward comments will deserve what they get.

Don’t believe me? Read of the inspiration prior to its arrival and disappointment at its failure in TV animated sit-com “The Simpsons.”

To quote Wikipedia (this time quite advisable);

The Simpsons episode 2F11, “Bart’s Comet”, Principal Skinner says he missed the chance to name a comet after himself once, but that he “got back” at Principal Kohoutek… “him and that little boy of his!”

[That redefinition of the AU recently by the IAU (He!, giggle), just ain't gonna save anyone!]

NancyAtkinson September 25, 2012 at 9:20 PM

Wow, I thought the article was pretty cautionary about the potential of this comet. Thanks ever so much for your “blithering blind” comment. Did you read the article or just the headline?

SJStar September 25, 2012 at 10:17 PM

Let’s see. How about Micheal E. Bakich (Astronomy Magazine) saying;

About a year from now, Comet C/2012 S1 (ISON) probably will become the brightest comet anyone alive has ever seen. How bright it could get is currently the subject of vigorous discussion among planetary scientists and everyday comet-watchers

I’ve read a dozen of these kinds of comments already!!

Frankly, I nearly choked on my cereal when I read your -16 magnitude!!

Where does that figure come from?

[To quote Astrobob of the AAVSO.. "Will C/2012 S1 (ISON) become a Great Comet, too? I’ll look into my crystal ball when more data becomes available." ] I think that was kinda my point.

Dav_Daddy September 28, 2012 at 1:34 AM

Hey SJ. I think you are giving the public at large more credit than they are due. The common Joe off the street will hear there is worlds brightest comet coming in November. Come November he will look up see nothing, maybe hear the late night comedy hosts crack jokes for the next few weeks. Come January it will be totally forgotten.

My own unscientific study of my girlfriend and her children confirms this. When asked to name comets they came up with “Hayley’s and that one where all the people killed themselves” (Halebop).

Dav_Daddy September 28, 2012 at 1:37 AM

Oh her 14yr old daughter also said that one that was supposed to hit Earth but I rejected that answer for being too vague.

Kevin Heider September 25, 2012 at 6:03 PM

Nancy, your article seems well written to me.

SJStar September 25, 2012 at 11:20 PM

I have deeply thought much more about your comment here, and the use of the word “blithering.” I really meant “startling”, and I was more talking about the broader non-scientific media who are almost clueless when it comes to astronomy.

I have quite wrongly used the meaning of this word, and agree when reading this again, that it is unfair, condescending and insulting. Most of your informative articles are far from showing imprecision, and are clearly always thoughtful, concise and direct to the subject at hand.

Considering the variety of articles you write; having to make the understandable from novices to experts and still present complex ideas in entertaining ways — is a none-to-easy task.
Please accept my sincere apologies for my mistake here.

NancyAtkinson September 26, 2012 at 1:41 PM

Thanks for your note, I appreciate it. I have added links to the article to the visibility calculations done by Daniel Fischer, which I should have included in the first place.

SJStar September 26, 2012 at 11:37 PM

Wow what a obscure source! It hidden in German too!

The article says the range of brightness is anywhere between magnitudes of -6 to -16, not -11 (which I assume you averaged?)
No matter how it is calculated, I cannot get past -10 magnitude, and this is agreed in the sources you linked.

Comet magnitude are calculated by m = H + 5 logDelta + 10 log r ; where H is the absolute magnitude, Delta is the Earth’s Distance, and r is the Sun’s Distance.

Firstly, distance of 2 million kilometres (0.013AU) for the sun is highly suspect, as the error is more than the distance! Few comets pass within 0.3 AU.

All hinges on the given absolute magnitude, which for most comets is very unreliable. At the present distance of this comet, we can only assume an average value. (The German source may have used the maximum value, but it actually doesn’t say how this was done.) Only five comets have been above ?1.5 absolute magnitude, but the average is around 2 to 6; say 4.

At 0.3 AU; m= 4+ 5 log(0.1)+10 log(1) = 0.0 magnitude

At 0.013AU, this is ; m=4 + 5 log (0.013)+10(log1) = -5.4

At 2 million kilometres, If m = 4 + 5 log (0.013)+ log(1) = -10.93

The highest value for H is ?1.8, meaning the best magnitude possible is ?11.3!!

Where does the ?16 come from? It is impossible!

This source is unreliable!

Kevin Heider September 28, 2012 at 3:34 PM

Be careful. Forward scattering can make comets appear very bright! JPL Horizons (as of Sept 28) shows ISON passing only 0.5° from the Sun around 2013-Nov-28 19:00 UT.

Michael Runow September 25, 2012 at 7:08 PM

She mentioned Kohoutek in the article, which was hardly sensationalistic. Nancy was very clear that we have insufficient information to make predictions of brightness. Still, this one is a lot closer than Kohoutek. 10X closer,100x the intensity.

SJStar September 25, 2012 at 7:38 PM

Perhaps, but it depends on the amounts of ices…

All I’m saying is don’t count your chicken before they hatch.

Really is ?11 or ?16 possible or ever observed? Let’s at least be realistic

SJStar September 25, 2012 at 7:26 PM

You say; “Just 2 million km distant from the Sun is incredibly close, and if the comet stays intact, it could reach a brilliant negative magnitude of between -11 and ?16.

Please. This would make it the brightest comet of all time by more than 3 to 8 magnitudes. As you’ve seemingly and brutally deleted my first comment on Kohoutek, please show us the evidence for such a magnitude. I really don’t, frankly, believe it.

Michael Runow September 25, 2012 at 8:03 PM

The great comet of 1882 was estimated to be -15 to -20 magnitude. You’re trolling a post on a comet? Really?

SJStar September 25, 2012 at 9:34 PM

Why is it every time someone makes a comment and someone disagrees with it, your automatically judged as a troll?

Estimated magnitudes for comets is dubious at best. Sure some sources quote 17th, but that was just a few short hours against the brilliant glare of the sun. More realistic values or reliable brightness are at best around ?11.
It is mostly speculation not a measured value.Yet that is irrelevant…

The point is that predicting magnitudes are notoriously wrong and that they are variable due to the composition of the comet, the activity of the sun, the position of the earth, the error in the orbital positions, the size of the comet, etc.

This article here is so notorious, because like many historical comets have been more often less spectacular that being brilliant, and all this story is doing is making hype instead of its scientific based reality. Novices especially get caught out in the kind of media sensationalism, and when it doesn’t meet expectation, it does great disservice by making them and the public turn away from astronomy and science.

One only has to look at the nonsense like the Mars at opposition being “large as the moon” story to see the damage sensationalism can do.

Universe Today is supposed to be promoting science, based on observable evidence, and not reducing it to ‘improbables’ like astrology or scandalmongering.

As my question poses. Where is the evidence that this comet will reach ?11 to ?16? Based on some scant observations of 18th magnitude comet that still has a long way to go before we know the definitive motion in where it is headed.

Nick Howes is rightfully cautious, expecting it “might make a negative magnitude.” (He says this because of the limitations of the available information.) Yet Nancy here says it could be 25,000 to 25,000,000 times brighter!

Pray tell, why the gapping difference. Conservative is one thing. Best so grossly over the top is another. An astronomer versus a media publicist — I’d know who I choose!

Michael Runow September 26, 2012 at 3:08 PM

You’re a troll because you trashed the author while obviously not having even read the entire article.

SJStar September 26, 2012 at 10:45 PM

Opportunist comments like this is a kinda trolling too…

Jeanette Dunphy September 26, 2012 at 1:35 AM

Great report Nancy. :) Thanks. I will be sharing.

Nick Howes September 28, 2012 at 11:38 AM

Stuart has raised some very important points. I don’t think it’s trolling, just a cautionary note to all that this comet, whilst the IAU predict mag -13.1, our team are estimating at around mag -8 to -9, and Daniel came up with -15.74 (which is the -16 quote being banded about), it could fizzle to nothing too. Nancy’s superb initial article was both fair and balanced (and we spoke about the images etc). Our team has papers published in Aphys journal and Icarus on comet analysis, we’er doing Afp value analysis on the dust probably later today (real science!), and over the coming months will build a picture of the likelyhood of this comet performing or not, but even then, who knows, it could be slammed by a CME, fragment…pic an option… nobody knows, but it’s fun to hope and dream it will reach close to some of the amazing values professional scientists like the IAU are estimating

Kevin Heider September 28, 2012 at 3:47 PM

The -15.74 figure is what JPL Horizons “Sun-Observer-Target angle” (S-O-T) lists for 2013-Nov-28 19:03 UT when the comet is only 0.4843° from the Sun. I suspect forward scattering has a lot to do with the brief spike in brightness. Of course that close to the Sun, the comet will probably be lost in the sky glare for casual observers.

Comments on this entry are closed.

Previous post:

Next post: