Changing Planet

Comet ISON Cliffhanger

Comet ISON, imaged by longtime amateur astrophotograper Damian Peach in the U.K. He used a 4-inch f/5 telescope for 12 minutes of combined exposures on November 15th. Credit: Damian Peach /

Astronomers keeping a close eye on the highly-anticipated Comet ISON, are reporting that ‘something’ is happening to the icy visitor as it quickly plummets towards the sun.

And it may, or may not, be bad news for skywatchers.

What has comet scientists puzzled about Comet ISON’s fate are the latest observations, which show a dramatic drop in the comet’s emissions of hydrogen cyanide gas. The gas is thought to normally hide in pockets beneath the comet’s nucleus surface. When the surface ice boils off as the comet approaches the sun, the gas is released into space and the comet develops a tail.

However, for some reason these emissions appear to have declined significantly from Comet ISON in the past week or so. That may be an ominous hint that enough ice has vaporized, due to the increasingly-intense solar heat, that the comet’s frozen 1.2-mile-wide (2 kilometer) nucleus has started to fracture and disintegrate.

Watch Comet ISON

Is there still a chance Comet ISON will survive its encounter with the sun on Thursday, November 28th and become a great sky show in December? You bet!

Astronomers have definitely not written off the comet yet, noting that comets historically have behaved in unpredictable fashion, and what we are witnessing now is an unprecedented astronomical event, the likes of which has never been observed in such detail. during a NASA news briefing on November 26th NASA scientists gave ISON up to 40% chance of surviving and said, even if the nucleus does break up it may still give the general public quite a sky show early December with a long sweeping tail visible.

Karl Battams, a comet scientist with the U.S. Naval Research Laboratory in Washington, D.C. who blogs on NASA’s Comet ISON Observing Campaign website put it this way on Monday, “Comet ISON is a dynamically new sungrazing comet, fresh in from the Oort Cloud, and the last time we saw an object like this was never! Furthermore, a sungrazing comet just three days from perihelion [closest approach to the sun] has never been studied in this kind of detailwe’re breaking new ground here! When we factor in your standard ‘comets are unpredictable’ disclaimer, what we have is a huge recipe for the unknown.”

One thing we know for sure is that when Comet ISON reaches perihelion on US Thanksgiving Day, it will be flying right through the hellish outer atmosphere of the sunmissing its searing surface by only 684,000 miles (1.1 million kilometers). That is a little less than only two and a half times the distance from Earth to the moon.


At its closest point to the sun Comet ISON will be about 1.1 million km from its surface. Credit: NASA
At its closest point to the sun Comet ISON will be about 1.1 million km from its surface. Credit: NASA

NASA will host a live Google+ Hangout with comet experts on November 28 from 1 pm to 3:30 pm EST (18:30–20:00 UT)at exactly the time ISON slingshots around the sun.  Dubbed ‘Fire vs. ISON – the Epic Battle Live‘, the online event will give the public a chance to watch, ask questions of scientists, and track the comet live through streaming images beamed back from NASA’s Solar Dynamics Observatory (SDO) spacecraft, which is watching  ISON’s closest approach to the sun.

If it manages to survive its roasting, the comet could still become an impressive naked-eye comet with a long tail in the pre-dawn sky. Or it could become just a faint smudge in binoculars.

In any case, sky-watchers around the world are gearing up for the chance to catch sight of Comet ISON. In the best-case scenario that it does round the sun intact, observers should start scanning the very low eastern morning skies about an half hour to an hour before local sunrise starting Sunday, December 1,  for a view of the comet in the glare of twilight.  Every day thereafter the comet moves a bit higher in the morning sky as it treks farther away from the sun and back towards the outer solar system.

The moment of truth for Comet ISON has arrived and it’s a nail-bitter for sure. Will it dazzle or fizzle? Time will tell and no doubt the world is watching.


Follow Andrew Fazekas, the Night Sky Guy, on Twitter and Facebook.

Andrew Fazekas, aka The Night Sky Guy, is a science writer, broadcaster, and lecturer who loves to share his passion for the wonders of the universe through all media. He is a regular contributor to National Geographic News and is the national cosmic correspondent for Canada’s Weather Network TV channel, space columnist for CBC Radio network, and a consultant for the Canadian Space Agency. As a member of the Royal Astronomical Society of Canada, Andrew has been observing the heavens from Montreal for over a quarter century and has never met a clear night sky he didn’t like.
  • Marietta Alexander

    Hopefully Major Ed Dames is wrong about ISON. Do not want the KILL SHOT that plunges the earth into darkness mixed with fire balls. Want this to be an educational experience and not the last known experience mankind has with a comet!

  • David F Pawlowski

    Do not worry about Comet Ison, what Dames sees is Betelgeuse going supernova. Instead you might want to ask your favorite sober astronomer about the possibility of a new (ISON origin) annual micrometeorite shower starting with Earths transit of Ison’s inbound orbital path that our planet will cross sometime in mid-January 2014 (Jan 13th – 17th). It is unlikely that we will experience a Chelyabinsk type superbolide (e.g. 500 kiloton high altitude energy yield) but may experience some smaller bolides streaking across the sky similar to those recorded in a famed woodcut drawing from Europe that depicts bolides observed during Earth’s transit of Halley’s comet tail. It is most likely that Earth will enjoy a micrometeorite shower like we do annually with the Geminid and South Taurid (Comet Encke) origin comet debris trails. Don’t worry, but learn what you can about Betelgeuse.

  • Bette Grose

    I believe I captured a picture of the Comet Ison at 8:25AM. Need to know how to send the picture.

  • David

    Does anyone have any idea what Marietta Alexander is talking about? Who is Major Ed Dames?

  • David

    OK, I googled him. Never mind my question. I really don’t want to be party to starting/prolonging that kind of conversation here.

  • Bubba Smith

    Earth is not going to be destroyed by this comet, it will just be (hopefully) fun to watch. The conspiracy theorists are going crazy with this (like they do everything) and once it passes with nothing happening to the Earth, they’ll jump on the next conspiracy theory/disaster forecast.

  • Comet C/2012 S1 ISON Facebook Page

    Comet C/2012 S1 ISON Facebook Page –

  • Fred Zyphal

    A couple of serious problems with this article … first, if ISON survives perihelion, it will then be an evening comet, not a “pre dawn” comet … second, ISON is not in the ecliptic plane, it’s approach is from a very unusual angle, and never even came close to crossing the Earth’s orbit.

  • Scott Rogers

    Fred, a major problem with your comment- Won’t comet ISON be viewable both in the dawn *and* all night?

  • Eric Lonetti

    Fred Zyphal, you’re wrong. It will slingshot around sun and “shoot” back out in almost the same direction it came in san 20 degrees or so. Your analysis doesn’t take into account that it slingshots around sun not merely passes by it. If it passed it we would have to let the western horizon block out the sun and watch it exit our solar system.

  • Eric Lonetti

    Also Fred. Sure it might have passed earths orbit where earth is positioned in (example) Feb or so. I already read an article that said Comet Ison may produce a new meteor shower in 2014 as the Earth moves ahead into where Comet Ison passed. So technically the Earth was not near Ison right now but will move into where it was. That means that if comet ison came in 2 or 3 months later earth would be much closer. This doesn’t mean it definitively it would collided with earth a different time of year because dust can drift. I’m not a professional astronomer as I choose a different science (geology). You really would need to talk to a Astronomer or Astrophysicist for details on Ison’s orbit vs. Earth’s orbit.

  • Robert Victor

    In a post earlier today, Fred Zyphal wrote ” … first, if ISON survives perihelion, it will then be an evening comet, not a “pre dawn” comet …” Actually, the Comet will changes its direction by more than 180 degrees as it rounds the Sun at perihelion, and, if it survives, will move rapidly northward and west from the eastward moving Sun, which will place it higher in the morning sky than in the evening. For a detailed description of where to find it in the morning sky, visit
    Also included there is a link to an excellent ISON finder chart from Sky and Telescope. The chart in their November issue came in very handy in helping me spot the faint Comet on several mornings through Nov. 18.

  • Ted

    Fred Zyphal, ISON will, after perihelion, be BOTH a morning and evening comet. But just barely an evening comet – Best views, by far, will still be in the morning.

  • Mark Bannister

    this is really wonderful to watch 🙂

  • Tom

    There are a couple of odd comments here. The earth’s annual orbit around the sun is a ballistic trajectory; so also is the highly elliptical path of this comet. But, the two paths never come anywhere close to intersecting. Even if the comet were to leave a stream of ticking time bombs all along its path, we would never encounter them. The reason is that its orbital path is highly tilted relative to the plane defined by the earth’s orbital path. Take the thumb and index finger of your right hand and form a closed loop by touching them together. Do the same with your left hand, but do it so that the two loops each pass through the other without making contact. Now it is easy to see why there is no chance of any collision. Note, though, that there is a good chance that the slingshot effect will send Ison on a path that no longer orbits the sun, i.e., out into the reaches of space. Now, the other thing I want to comment on is the statement by Fred Zyphal, claiming that Ison will become an evening comment if it survives its near-collision with the sun. Whether the comet appears to rise before the sun (and set before the sun) vs. rise after the sun (and set after the sun) depends on the position of the earth in its orbit, in relation to the approach and departure of Ison. Once ison has had it close encounter with the sun on the 28th, it will in fact pass to the other “side” of the sun, from our perspective, for a short period of no more than two days. During that time, it will appear to set after the sun and rise after the sun. Thus, on the 28th, and maybe also the 29th, Ison will in theory appear in the western sky, setting very shortly after the sun. But, there isn’t any chance that it will be visible, because it will be waaay too close to the sun, and will set before the sky has darkened enough for there to be any chance of seeing it. By the 30th, and certainly by the 1st of December, it will appear to crossed back to the same side of the sun from which it came, i.e., it will rise before the sun, and set before the sun. The separation distance and time, between cometrise in the east and sunrise, will gradually increase. Most likely this separation will not be great enough for the comet to be visible until around the 5th of December, at the earliest. If it is visible at all, the best days will probably be December 5 through 10. As it continues to rise earlier and earlier, it will move further to the north. Eventually it will be so far to the north that it will be circumpolar, i.e., visible from the northern hemisphere no matter the time of day, but by this time it will likely be so dim that you will need a telescope or binoculars to see it, and that assumes that it will even be bright enough to be seen earlier in December, and until we get ther, we just don’t know.

  • Amanpreet Singh

    Can ison be seen in INDIA (DELHI )

  • Uthopia Zexal

    Hey guys. i think the encounter with the sun will obviously melt up because either the heat from the sun will melt the comet from being to close, or the comet will go into the sun because of the gravitational pull of the huge sun. But never mind that, science has taken us to new place and has helped us understand how God the creator is so majestic in his ways!!!

  • El Gabilon

    The only thing certain about the universe is constant change. Here today, gone tomorrow. RIP ISOL!

  • albert lopez

    Comet ISON is now heading towards the sun and becoming a daylight comet will entirely depends on how it will overcome sol’s intense heat, watch live @

  • michel krooder

    is thear a live stream bicase we cant see it

  • Sarah Arnold

    I want to go to space for my birthday!I would really like that,a lot.

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