Comet ISON Update Dec. 1 – Watch The Video / Latest Science Observations

Comet ISON seen through SOHO’s eyes 

Just a brief update today. Comet ISON has left the eyes of SOHO, but it’s still there in STEREO-A through Dec. 7 and possibly longer if NASA decides to roll the spacecraft for a better view in the coming days. I checked today but no recent, high-res photos have been uploaded yet. I’ll post them when they arrive. You can still see the comet in the low-resolution picture below.

Comet ISON in a low-resolution photo taken by NASA’s STEREO-A solar probe at 3:18 p.m. today Dec.1. Click to enlarge. Credit: NASA

The last we saw of ISON, it continued to expand and fade on its outbound journey. We should know in a few days what it looks like from Earth’s skies when astrophotographers will be out in force attempting to record and see the comet’s dusty remains.

Amazing montage showing how the changes in Comet ISON’s brightness and shape between Sept. 24 and Nov. 15, 2013. Click to enlarge. Credit: Damian Peach

Meantime, enjoy this wonderful compilation of SOHO (Solar and Heliospheric Observatory) pictures taken with its two coronagraphs – LASCO C2 and C3 – and assembled by Pieter-Jan Dekelver from Belgium. Notice how much faster the comet moves when closest to the sun when ISON feels the sun’s gravitational force most strongly.

The International Astronomical Union published an electronic telegram No. 3731 today Dec. 1 with blow-by-blow scientific observations of ISON’s evolution during perihelion. Here’s a quick summary of the results:

* The comet’s nucleus disrupted hours before perihelion with the comet’s head fading from -2 magnitude (just shy of Jupiter’s brightness) to well below +1 magnitude shortly before perihelion.

* What remains after perihelion is a diffuse cloud of dust from the nucleus mostly transparent to the background stars. Late on Nov. 30 the main part of the cloud spanned about 1/2 degree and glowed weakly at magnitude 5.4.

* Z. Sekanina of the Jet Propulsion Laboratory, studying SOHO images, determined that ISON stopped producing dust 3 hours before perihelion. This jives with the photos taken shortly after perihelion showing that a sharp tip had replaced the larger, rounded nucleus.

* The nucleus or core of the comet is thought to have fragmented shortly before a sudden surge in brightness seen nearly 12 hours prior to perihelion.

* ISON’s post-perihelion, sunward-pointing tail may be composed of dust grains released 1-2 days before perihelion, while the eastward pointing tail (sticking out to the left of the comet) was made of dust released within an hour of perihelion and likely composed of graphite and metals.The streamer of much larger dust grains ejected long before the comet was near the sun completely disappeared during the comet’s near-brush with the sun.

10 Responses

  1. Edward M. Boll

    That is too bad. I guess you could say that ISON made comet of the month. With 2 days of no activity, I suppose we have to say good bye to viewing it for most of us. I was glad that part of it survived the Sun. The ISON tracker now puts it at magnitude 2.2. If they had been accurate, I suppose that a person could see it by now.

  2. Edward O'Reilly

    Yes,this sad conclusion to the Ison story is not what we’ve been hoping for over the last year.Disruption was always a possibility but most analyses of its core(including with the Hubble scope)indicated that Ison was large,compared to typical sungrazers,and had a fairly good chance to survive perihelion. Very sad.Oh well,to paraphrase Bogart in Casablanca,we’ll always have Lovejoy!(well maybe not always).

  3. Kevin

    Any comments on what we can expect when Earth goes through the “tail
    trail” of debris sometime near Jan 12th 2014?
    Comments on other doom and gloom websites “predict” lots of trash falling
    from the sky.
    Great video. Perfect music.

    1. astrobob

      Hi Kevin,
      Usually I don’t care for music with my videos but that was a good choice. The “shower” we MIGHT pass through will consist of particles so small that they will probably not be seen as meteors with the naked eye. NASA reported on this sometime ago. Here’s the link:

  4. “* The comet’s nucleus disrupted hours before perihelion with the comet’s head fading from -2 magnitude (just shy of Jupiter’s brightness) to well below +1 magnitude shortly before perihelion. – See more at:
    …really? that’s the consensus? What is your take Bob on fixed 17.6sec exposures unguided on an object that picks up speed at perihelion equaling dimmer looking exposure? The data is tainted for the close to perihelion shots. Am not saying it didn’t actually dim just that there is inaccuracy involved in the data interpretation. I suspect the error can be calculated to certain magnitude given time for analysis.

    1. astrobob

      Hi Kevin,
      Very hard for me to say. I presented the data but did not feel qualified to interpret it. No doubt others might have different magnitude estimates.

  5. Chuck

    Instead of being sad ISON didn’t hold together around the sun, be glad that all the hype made ISON, the most observed comet ever. Several weeks ago my Grandson and I were watching this show about comets on TV and I searched “when is the next comet”, and there it was headed for Mars, then on to graze the sun and then be flung back our way. How exciting, not only was there Ison and Lovejoy but we learned that there were many more. I had no idea so much was going on while I slept. I ordered a pair of 15×70’s and started getting up early with hopes of seeing these wonders in space with my own eyes. My Grandson is also showing an interest in the sky, So thank you Astro Bob for all the great information and maps and thank you Comet ISON for re-sparking an old flame.

    1. astrobob

      Hi Chuck,
      Thank you very much. I like your positive take on the comet. Have fun with those binoculars – Comet Lovejoy should look very nice in them!

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