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How Much of ISON Survived Its Closest Approach To the Sun? 84

Posted by samzenpus
from the a-thousand-little-pieces dept.
SternisheFan writes "This Ars Technica article examines what may be left of ISON and contains a detailed animated GIF from the NASA STEREO Ahead spacecraft. 'It looks like comet ISON, or most of it, did not survive its encounter with the Sun yesterday, when it made a close approach at just 1.2 million kms from that fiery surface. This distance may seem large, but it is close enough to have subjected the comet to temperatures of around 2,700C. To survive such a close shave with the Sun may sound unlikely, but a few other sungrazing comets have managed the feat during even closer passes. So some people hoped ISON would perform a death-defying stunt and emerge intact. ISON did not leave us without a final serving of mystery though. Soon after reaching its nearest point to the Sun (known as perihelion), there was no sign of it emerging afterwards. Twitter and news agencies were alight, lamenting its loss and assuming it disintegrated—RIP ISON. But then, moments later, new images emerged showing a hint of something appearing on the other side of the Sun. Was this still a diminished comet ISON or a ghostly version of its former self? Well, even comet experts are not sure.'"
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How Much of ISON Survived Its Closest Approach To the Sun?

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  • ...comet brains

  • by Taco Cowboy (5327) on Sunday December 01, 2013 @08:50PM (#45571547) Journal
    • by pr0t0 (216378)

      After watching several animated gif's of the event (like this one: http://arstechnica.com/science/2013/12/comet-ison-fizzles-but-theres-a-sting-in-the-tail/ [arstechnica.com]), I'm left a little perplexed. I was under the impression that as a comet approaches the Sun, the heat causes outgassing and evaporation, and the tail forms as the solar wind blows that away from the comet. Accordingly, I thought a comet's tail roughly always pointed away from the sun with maybe a slight curve due to momentum. But the gif's I'm seeing d

  • by Brad1138 (590148) <brad1138@yahoo.com> on Sunday December 01, 2013 @09:03PM (#45571621)
    in 1986...
    • by dkleinsc (563838)

      Or 1947, in Roswell, NM. Something involving a microwave oven and a supernova.

    • by arth1 (260657)

      March, 1997.
      Do you have your $5.75 and Nikes, and are ready to catch the outbound flight?

  • It's like they has their own 'snow physics' or somethin'.
  • by Tablizer (95088) on Sunday December 01, 2013 @09:19PM (#45571707) Journal

    So many idiots, so few comets.

  • ok. i'm down. i-Son.
  • by Gwala (309968) <adam@NOsPaM.gwala.net> on Sunday December 01, 2013 @09:23PM (#45571721) Homepage

    Probably a stupid question - but wouldn't the steam/plasma presumably have the same orbit as the original solid mass; similarly presumably wouldn't the solar wind blow the mass away fairly evenly - meaning in a long long time, it'll cool, condense and potentially (slowly) pull itself back together?

    • by Anonymous Coward

      no, liquidus would make it spread out and become "atmosphere" of the sun. Also there is no cooler masses lying around for it to give it's heat to, so no to the 2nd question.

    • I would think the suns magnetosphere would redirect any plasma, and possibly water steam would be effected by it too.

    • No, and no (Score:4, Informative)

      by Anonymous Coward on Sunday December 01, 2013 @09:55PM (#45571845)

      The ejected material could come off at a significant velocity, so it wouldn't have quite the same orbit.
      Solar wind (and light pressure) have more effect on small particles than large ones, since they act based on surface area (r^2) against mass (r^3). This is why the solar wind can sweep dust out of the solar system, but not planets.
      There is also drag from the corona to consider. The comet effectively did an air dip.
      TL;DR Any lost material was either blown out into space, or fell into the sun. Either way, this comet will not 'pull itself back together'

  • Define survived

    Its not like it was alive or anything

    Most of the non ice stuff will still be in pretty much the same orbit

  • How do they define temperature? The show happens in vacuum, there is no thermal agitation. Inside the comet this is another story, but are we able to measure the internal temperature?
    • by c0lo (1497653)

      How do they define temperature? The show happens in vacuum, there is no thermal agitation.

      Not quite vacuum but even if it would be so: black-body radiation [wikipedia.org] is a measure of temperature for radiative-only cases.

      • by manu0601 (2221348)
        Is black body radiation reliable for something that is breaking up, with chunks turned into vapor? And I understood the comet wen hidden by the mask protecting the observing tools from direct sun light...
        • Re:2700 degC? (Score:5, Informative)

          by c0lo (1497653) on Monday December 02, 2013 @01:33AM (#45572517)

          Look, you asked how to define the temperature in vacuum and I answered
          Put in a good number of assumptions and, based on them, one (with enough skill in the craft) will be able to estimate [wikipedia.org] the internal temperature.
          Of course it will still be an estimate and nothing more (one doesn't need to ask, it's only natural that precise data could be obtained only if you have unambigous direct observation of the phenomenon - and not even then)

          Other than that, yes, the black-body radiation is correct for all macroscopic bodies (be them in one piece or crumbling) - the only requirements are: that body to expose a surface, be made of enough particles [wikipedia.org] to display a statistical behavior and be at thermal equilibrium.
          There was this guy, Plank [wikipedia.org], that put his name at stake on the correctness of it: to date, nobody ashamed him (his initial estimation of the constant was within 1.2% of the more precise value we accept today, which is quite remarcable IMHO)

    • by Kentari (1265084)
      I believe this is the estimated surface temperature on the sunlit side of the comet's nucleus. Just like the surface of the Moon and Mercury have a temperature of 390K and 670K despite not having a significant atmosphere.
  • by Anonymous Coward

    It Still Outshines Nothing

  • Really, really hot (Score:4, Informative)

    by ArcadeMan (2766669) on Sunday December 01, 2013 @10:03PM (#45571863)

    Moments later, new images emerged showing a hint of something appearing on the other side of the Sun. Was this still a diminished comet ISON or a ghostly version of its former self.

    What emerged from the other side was almost, but not quite, entirely unlike tea.

  • JSON? (Score:2, Funny)

    by belmolis (702863)
    At first I read that as JSON and wondered what had happened to it.
  • by Solandri (704621) on Monday December 02, 2013 @01:16AM (#45572477)
    Not to be confused with the spectacular comet Lovejoy (2011). Both were discovered by the same guy so bear his name.

    Lovejoy (2013) isn't as bright (barely visible to the naked eye), but should be easily visible with binoculars. It made its closest approach to Earth on Nov 19 and will reach perihelion (closest approach to the sun) Dec 25. It's fairly high up in the Northern hemisphere sky right now.
    http://earthsky.org/space/how-to-see-comet-lovejoy-c2013-r1-charts-photos [earthsky.org]
  • "Previous reports of Comet ISON's death may have been somewhat exaggerated, but this time it looks like the real thing [death].

    Remnants of the object once touted as the "comet of the century" passed through the viewing field of the Solar and Heliospheric Observatory in the wake of Thursday's close encounter with the sun -- and as it passed, the bright spot that survived grew dimmer and dimmer.

    "I do think that something emerged from the sun, but probably a very small nucleus or 'rubble pile.' and I fear that

  • is how, all over the interwebs, comet ISON is being described - and sometimes outright mourned - as if it had been / still were an animated being. Strange. If it had been my dog, or any dog for that matter, not surviving a close encounter with the sun - well then, hell yes. But ISON is only a chunk of dirty ice....
  • While the Sun's heat probably played a role in ISON's destruction, I think the main reason it broke up was because of the Sun's tidal forces. ISON was within its Roche limit, where the tidal effects of the Sun were enough to overpower ISON's own gravity, tearing the comet apart. Most of it is probably orbiting the Sun right now as a very small ring.

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