Comet ISON Update Dec. 4 – A Stubborn Fellow

Low-resolution image from one of the cameras on STEREO-A taken on Dec. 1. Called a “beacon image” it’s a frame from a 24-hour daily stream of data from the spacecraft. Credit: NASA

Comet ISON lives! OK, it might be on life support, but the comet written off as dead a week ago still glows in recent photos taken by the STEREO-A cameras. While no one’s seen it from the ground yet, we’re getting close to that opportunity.

One of the latest STEREO-A beacon photos may or may not show the comet. For some reason, the resolution in photos made today is poor, making the comet’s identification dificult. Credit: NASA

This Saturday Dec. 7 the comet will appear very low in the southeastern sky for a brief period just before the start of morning twilight. I doubt anyone will see it with their eyeballs but intrepid astrophotographers are eager to photograph it.

High resolution photo from STEREO-A’s H1 heliospheric imager camera showing Comet ISON on Dec. 1. Although taken at the same time, it appears fainter here. Differences in picture quality and exposure are probably why. Credit: NASA
Latest hi-resolution photo from STEREO-A shows continued fading of Comet ISON. Credit: NASA

Based on these photos, the latest I could find, ISON shines about as brightly as the nebulosity in and around the Pleiades star cluster. Not bright by any stretch, small telescopes will still show the brightest parts of the cluster’s cocoon-like nebula from a dark sky. That’s my educated guess on the comet’s potential visibility. Hopefully we’ll see photos and magnitude estimates from the ground very soon.

Most recent STEREO-A image published Dec. 3 at 4:49 p.m. CST only hints at the comet’s presence. Credit: NASA

UPDATE Dec. 5: Latest hi-res STEREO-A photo shows ISON barely there.

Comet Lovejoy photographed this morning from Italy. Details: Camera piggybacked on a telescope, 430mm lens at f/6.3, 142 second exposure, ISO 800. Credit: Giorgio Rizzarelli

One comet remains bright – Lovejoy. It’s traveling through the constellation Bootes in the wee hours before dawn and can still be viewed in binoculars. Click HERE for a finder map.

18 Responses

  1. Mike

    Just got done explaining to a small group of folks yesterday about this cool fickle comet that blew up somewhere near the sun last week. Looks like I need to go back and edit my opinion on that one. That poor old tom cat sure does have nine lives.

    Hope you keep out of the snow drifts Bob, stay warm and dry.

    1. astrobob

      Hi Mike,
      Well, you’re certainly close to the truth. Whatever is left after the blowup still shows but maybe not for much longer.

  2. Edward M. Boll

    Well it is like David Levy is famed for saying that cats hace tails. I guess that ISON has 9 lives too.

  3. Troy

    Is there any possibility what is now essentially a debris field will intersect the Earth’s orbit and cause another annual meteor shower?

    1. astrobob

      Hi Troy,
      Not likely. The particles released from the breakup will continue to travel along the orbit, and though they’ll expand into a larger cloud, the comet and cloud pass a great distance from Earth even when closest – some 40 million miles. That’s nearly halfway to the sun – too far to give us a shower.

      1. Munks

        Yes but the tail is massive and growing at a rate or five millons miles a day,and even though the comet chunks will pass within 41 million miles of the Earth the tail will… well you do the math.

        1. astrobob

          Hi Munks,
          The thing is though, the comet debris will be traveling in the same general trajectory as the comet and pass well above Earth’s orbital plane on its outbound leg. Not only will it be far from us, but “above us” so to speak. Earth won’t intersect the debris. Even if we did get a graze, ISON was a small comet and the tiny dusty debris from its rapidly expanding and thinning cloud/tail would not be a concern. We pass through debris left by comets all the time – in virtually every meteor shower. We’ve also been through at least one comet tail (Halley) before with no troubles. Comet tails are not massive in the sense they have lots of matter. They’re made of virtually nothing but can grow to great lengths and put on a great show.

  4. Mike Conners

    The trajectory of comet ISON debris may become a matter for concern vis-a-vis potential involvement with our Earth and/or the moon. The 600 previous potential trajectories were based on the comet remaining intact. Given the difficulty in tracking smaller objects entering the earth’s atmosphere, the international community may wish to add resources to observe the debris over the next three to four weeks.

    1. astrobob

      Just the same, 40 millions miles is a tremendous distance from Earth, and the debris will closely follow the comet’s orbit. Venus, when it’s closest to Earth, is still 27 million miles away, much closer than any potential comet debris. ISON debris will even be farther from Earth than Mars when that planet is closest to us. I think we’re safe.

      1. Bernd

        the ison orbit was calculated based upon the mass of the intact comet. The left-overs having a different mass might be influenced by the suns’ gravity field differently leading to a different orbit. How does this factor in for the projected distance to earth?

        1. astrobob

          The leftovers from the break up continue to travel along the same orbit as the original comet while slowly expanding over time. Even if the cloud expanded to the distance from here to Mars, and Earth passed through it, there would be almost nothing to show. Comet ISON is not a massive object – just a couple kilometers and much of that ice that vaporized at perihelion.

  5. Edward O'Reilly

    It will be interesting to see if any ground based scopes are able to pick up Ison’s remnants. Sounds possible but very challenging.Might need a scope with at least a 10 inch mirror?

  6. Wayne Hawk

    Aloha All!
    I think we all have to agree that this comet has “lasted” as long as it has. Look how long and interesting it is. We’re still using our best “stuff” to watch it and the scientific “chatter” has been interesting, on just about ALL levels, don’t you think? Or don’t you? :-}

    As always, great articles and photos…the best!

    Aloha For Now!

    1. astrobob

      Hi Wayne,
      I love all the discussion – both public and scientific. Unlike Comet Elenin in 2011, the amount of doomsday chatter about this comet has been less. I think the various agencies, science geeks and others have tried to inform and answer questions as best they can. Thanks for the kind words Wayne!

  7. mishiro

    There are several websites that indicate that ISON was the size of Australia. If that’s the case, wouldn’t it leave a huge debris field that would intersect Earth’s orbit and cause a large meteor shower?

    1. astrobob

      Hi mishiro,
      Comet ISON is (was) no more than 3 km (1.8 miles) across. That’s typical for comets. The dust cloud left behind after it broke up might be Australian-sized but the material is mostly very fine dust with smaller rocks spread out. Since the cloud will be many millions of miles from Earth and passes far over Earth’s orbit on its way out, no meteors from it are expected. There is a chance for a meteor shower from very fine debris left by the comet before perihelion (closest approach to the sun) in mid-January. It’s uncertain whether the particles are big enough to be leave meteor trails, so we might or might not see anything.

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