Comet ISON Alive And Well; Obscure Comet C/2012 X1 Bursts Into View

Comet ISON on Oct. 9 photographed by the Hubble Space Telescope. The pressure of sunlight pushes dust particles released by vaporizing ice back to form the tail. The smooth and symmetric appearance to the comet’s head is another good sign that ISON remains intact. Credit: NASA / ESA

Recent photos taken by the Hubble Space Telescope show that Comet ISON remains in one piece as it plunges ever closer to the sun. That’s good news. Had the nucleus broken into pieces, Hubble would have seen evidence for multiple fragments. While a splitting comet makes for fascinating observing it also spell its end. Each fragment fizzes away leaving a tail without a head.

We don’t want to happen to Comet ISON. It would mean the end of our hopes for a great show after it passes closest to the sun on November 28.

Comet ISON on April 10 showing the bright polar jet (fan at the comet’s front end) of fresh material expelled from the icy nucleus. Credit: NASA / ESA

One change we CAN see in the Hubble photos is the disappearance of a bright jet of material streaming away from the nucleus. This fountain-like feature results from fresh ices, which contain dust and other materials, vaporizing from fissures or cracks in the icy body of the comet. Sunlight heats ice below the surface to form gas-filled cavities under pressure. When the gas finds a vent or passage to the surface, it erupts in a jet of material similar to air rushing from a balloon.

Comet ISON on Oct. 20 with its green, gaseous coma / head and dusty tail. Credit: Rolando Ligustri

Comparing the two Hubble pictures we can see that the dust jet’s gone – perhaps it turned off temporarily. Photos taken by amateur astronomers, which have a much larger field of view than the Hubble, show an ever-lengthening tail. All these changes make watching comets a lot of fun.

At present, Comet ISON is still near Mars in the morning sky before dawn. Moonlight will compromise our view of the 10th magnitude “fuzzy glow” for about another week. Speaking of Mars, mission controllers attempted to photograph ISON with the Mars Opportunity Rover during its flyby earlier this month, but the comet was too faint to show in the rover’s panoramic camera. I still haven’t heard whether the Curiosity rover had better luck.

Comet C/2012 X1 (LINEAR) experienced a bright outburst in the past couple days and will become an easy target in small telescopes as the moon wanes. This photo was taken earlier today Oct. 21. Click for more information. Credit: Ernesto Guido, Nick Howes and Martino Nicolini

Meanwhile, just a day ago, the obscure 14th magnitude comet C/2012 X1 (LINEAR) suddenly brightened some 150 times times to 8.5 magnitude.

Here’s a object very few people were paying attention to that’s now bright enough to spot in binoculars under a dark sky. The sudden flare may originate from a massive buildup of gas inside the comet that fractured and broke off a good-sized chunk of comet crust.

Something similar happened to Comet Holmes in October 2007 when it brightened over half a million times from magnitude 17 to 2.8 over the space of only 42 hours. C/2012 X1 currently shines in Coma Berenices low in the dawn sky. It’s about 2′-3′ arc minutes across (less than 1/10 the diameter of the full moon) with a small, bright core. I’ve included a general finder map that shows the comet’s position and stars down to about 6th magnitude.

Closeup map showing the comet’s location on tomorrow morning Oct. 22 through Oct. 27. Use the star Beta and Alpha Coma Berenices as jumping off points. Stars shown to magnitude 9.0.  Stellarium

If X1 remains relatively bright, we’ll soon have four comets viewable in small telescopes by early November – Encke, ISON, Lovejoy and X1 LINEAR!

17 Responses

    1. astrobob

      Hi Dmitry,
      I took the difference to between 14 and 8.5 as 5.5 magnitude. A 5 mag. difference is 100 times brighter; a 6 mag. difference is about 250 times brighter. I went in between at around 200 times brighter.

  1. Edward M. Boll

    It looks like I will see snow before the Fall comets. Continued overcast and unseasonably cold for October.

    1. astrobob

      Likewise Duluth Edward. Pity so many comets are out in one of the worst observing months of the year for the N. U.S.

      1. You’ve never visited the North-West of England then? Atlantic front after Atlantic front, cloud, rain, cloud, rain. But we’re English, so “mustn’t grumble” !!

        1. astrobob

          Hi Simon,
          I’ve heard England’s not the best for observing. We might get a few weeks of bad weather but then it can clear up for a week or two at a time. Late Oct. though Dec. is not the best for my area though. Good luck and persevere!

  2. Edward O'Reilly

    Four comets at one time;will definitely try for all 4 once the(stupid) moon finally gets out of the way! Any guesses as to whether C/2012 X1 will brighten a bit more?

    1. astrobob

      Nothing threatening so far. If it starts producing stronger X-class flares, satellite and electrical transformer damage (power grid) is always a possibility. No X-class flare has damaged any transformers or power networks in the U.S. this year.

  3. leon vaner

    Hi, i live in south africa and is absolutely facinated by the aproachin comets, soon to be visible. Can you please email me an idea of location and direction to where i can observe comet ison. I have very little knowledge on this subject matter and i woukd reaaly need a basic instruction. It would be greatly appreciated. Thank you, leon

    1. astrobob

      Dear Leon,
      Right now you have a better view of Comet ISON than we do in the north. It’s between Spica and Mercury about 1 1/2 hours before sunrise, but it will be low in your eastern sky. Unfortunately it will not be visible from South Africa after it passes the sun because the comet moves rapidly to the north and quickly disappears below your horizon. If I can get time, I’ll make a map and send you a link to it.

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