From AGU: comet ISON’s struggle of Fire and Ice

San Francisco – After a year of observations, scientists waited with bated breath on Nov. 28, 2013, as Comet ISON made its closest approach to the sun, known as perihelion. Would the comet disintegrate in the fierce heat and gravity of the sun? Or survive intact to appear as a bright comet in the pre-dawn sky?

Some remnant of ISON did indeed make it around the sun, but it quickly dimmed and fizzled as seen with NASA’s solar observatories. This does not mean scientists were disappointed, however. A worldwide collaboration ensured that observatories around the globe and in space, as well as keen amateur astronomers, gathered one of the largest sets of comet observations of all time, which will provide fodder for study for years to come.

Video follows: 

On Dec. 10, 2013, researchers presented science results from the comet’s last days at the 2013 Fall American Geophysical Union meeting in San Francisco, Calif. They described how this unique comet lost mass in advance of reaching perihelion and most likely broke up during its closest approach, as well, as summarized what this means for determining what the comet was made of.

“The comet’s story begins with the very formation of the solar system,” said Karl Battams, an astrophysicist at the Naval Research Lab in Washington, D.C. “The dirty snowball that we came to call Comet ISON was created at the same time as the planets.”

ISON circled the solar system in the Oort cloud, more than 4.5 trillion miles away from the sun. At some point a few million years ago, something occurred – perhaps the passage of a nearby star – to knock ISON out of its orbit and send it hurtling along a path for its first trip into the inner solar system.

The comet was first spotted 585 million miles away in September 2012 by two Russian astronomers: Vitali Nevski and Artyom Novichonok. The comet was named after the project that discovered it, the International Scientific Optical Network, or ISON, and given an official designation of C/2012 S1 (ISON). When comet scientists mapped out Comet ISON’s orbit they learned that the comet would swing within 1.1 million miles of the sun’s surface, making it what’s known as a sungrazing comet, providing opportunities to study this pristine bit of the early solar system as it lost material while approaching the higher temperatures of the sun. With this knowledge, an international campaign to observe the comet was born. The number of space-based, ground-based, and amateur observations was unprecedented, including 12 NASA space-based assets observing Comet ISON over the past year.

Near the beginning of October, 2013, two months before perihelion, NASA’s Mars Reconnaissance Observer, or MRO, turned its HiRISE instrument to view the comet during its closest approach to Mars in October 2013.

“The size of ISON’s nucleus could be a little over half a mile across — at the most.  Very likely it could have been as small as several hundred yards,” said Alfred McEwen, the principal investigator for the HiRISE instrument at Arizona State University, in Tucson.

In other words, Comet ISON might have been the length of five or six football fields. This small size was near the borderline of how big ISON needed to be to survive its trip around the sun.

During that trip around the sun, Geraint Jones, a comet scientist at University College London’s Mullard Space Science Laboratory in the UK studied the comet’s dust tails to better understand what happened as it rounded the sun. By fitting models of the dust tail to the actual observations from NASA’s Solar Terrestrial Observatory, or STEREO, and the joint European Space Agency/NASA Solar and Heliospheric Observatory, or SOHO, Jones showed that very little dust was produced after perihelion, which may suggest that the comet’s nucleus had already broken up by that time.

A white plus sign shows where the Comet should have appeared in this SDO image.
This image from NASA’s Solar Dynamics Observatory shows the sun, but no Comet ISON was seen. A white plus sign shows where the Comet should have appeared.Image Credit: NASA/SDO
CLICK FOR LARGER IMAGE

While the comet was visible in STEREO and SOHO images going into perihelion, it was not visible in the data from NASA’s Solar Dynamics Observatory, or SDO, or from ground based solar observatories during its closest approach to the sun. Dean Pesnell, project scientist for SDO at NASA’s Goddard Space Flight Center in Greenbelt, Md., explained why Comet ISON wasn’t visible in SDO and what could be learned from that: SDO is tuned to see wavelengths of light that would indicate the presence of oxygen, which is very common in comets.

“The fact that ISON did not show oxygen despite how close it came to the sun provides information about how high was the evaporation temperature of ISON’s material,” said Pesnell. “This limits what it could have been made of.”

When Comet ISON was first spotted in September 2012, it was relatively bright for a comet at such a great distance from the sun. Consequently, many people had high hopes it would provide a beautiful light show visible in the night sky throughout December 2013. That potential ended when Comet ISON disrupted during perihelion. However, the legacy of the comet will go on for years as scientists analyze the tremendous data set collected during ISON’s journey.

About these ads

41 thoughts on “From AGU: comet ISON’s struggle of Fire and Ice

  1. …astronomers gathered one of the largest sets of comet observations of all time, which will provide fodder for study for years to come.
    ——————————–
    It’s a wise astronomer that knows its own fodder.

  2. I think people should research this thoroughly. This “dead comet” is still showing on their iSWA Cygnet Streamer. Please research “extinct comets”. The main difference between a comet and an asteroid is the presence (or lack of) ice, coma, and a tail.

    This is why they still plan on tasking Hubble to “look” for ISON, because if it did become just an asteroidal body, we wouldn’t be able to see it. Nor would any amateur astronomer, for that matter. This is why spaceweather.com does not have an “asteroid photo gallery”.

    Is comet ISON dead? Yes. Is Asteroid ISON alive — we will not know until Hubble looks.

  3. Who wrote this press release… didn’t bother to check basic information I guess. HiRISE is at the U of A in Tucson and to top it off ASU isn’t even located in Tucson either. Plus, Alfred McEwen is a professor at the U of A. Sheesh!

  4. “At some point a few million years ago, something occurred – perhaps the passage of a nearby star – to knock ISON out of its orbit and send it hurtling along a path for its first trip into the inner solar system.”
    ===========
    Last I heard, all it takes is a butterfly.
    ” a nearby star” ?.
    When was the last time we were “nearby” another star ?

    I think the time-frame might want to extend into billions of years.

  5. u.k.(us) says:
    December 12, 2013 at 2:10 pm

    Last I heard, all it takes is a butterfly.
    ” a nearby star” ?.
    When was the last time we were “nearby” another star ?

    I think the time-frame might want to extend into billions of years.

    =======================================

    Stars actually move quite quickly (at least in astronomical terms) relative to each other.

    For example, Barnard’s Star, which is currently 6 light years away will close to 3.75 light years by the year 9800 AD.

    So the idea of comet ISON being disturbed by a passing star millions of years ago is entirely plausible.

  6. Anything is possible says:
    December 12, 2013 at 2:33 pm
    So the idea of comet ISON being disturbed by a passing star millions of years ago is entirely plausible.
    The time [half the period p] it takes a comet to fall from a distance a is given by Kepler’s 3rd law p^2=a^3. With a = 100,000 AU we get p/2 = 16 million years.

  7. Anything is possible says:

    December 12, 2013 at 2:33 pm
    =============
    I guess, but would its gravity well have anymore force than a butterflies wing beat ?
    I’m thinking it would be much less ?

  8. Ison must have been a climate scientist. Once it realized the sun controls climate its head exploded.

  9. I’m much more interested in those Coronal Mass Ejections (if that’s what’s spewing spectacularly from the orb in that video.) Saints pr’sairve us!

  10. I never understood what the big deal was. It wasn’t the biggest comet. It wasn’t brightest either. It’s only claim to fame, passing close to the sun.

    If that’s all it takes to get astronomers excited these days, God help us.

  11. So Leif,

    The time [half the period p] it takes a comet to fall from a distance a is given by Kepler’s 3rd law p^2=a^3. With a = 100,000 AU we get p/2 = 16 million years.

    I unfortunately don’t have the time to investigate this but (obviously) which of the closest stars are on a vector that would have made them closer to ol’ Sol 16000000 years ago?

  12. That is awesome. I wonder what impact it may have had on the sun itself?

    The perception of no O2 is interesting to say the least. What was it made of ?

    Where are our expert analyzers? ;’)

  13. Robert of Ottawa says:
    December 12, 2013 at 4:04 pm
    which of the closest stars are on a vector that would have made them closer to ol’ Sol 16000000 years ago?
    We don’t know the orbits of the stars accurately enough to speculate about that so long ago.

  14. Brian R says:
    December 12, 2013 at 3:43 pm

    I never understood what the big deal was. It wasn’t the biggest comet. It wasn’t brightest either. It’s only claim to fame, passing close to the sun.

    If that’s all it takes to get astronomers excited these days, God help us.

    ==========================================================================
    What the scientist hoped to learn from it aside, I think much of the excitement had to do with the fact that because it did pass so close to the Sun, it could have been a very bright comet.
    I’ve only seen one comet with the my naked eye. I think it was Hyakutake in 1996.
    It was bright enough that I could see it in a restaurant parking lot in the city. It looked kind of a seed from a cottonwood tree. No tail per say but an off-center fuzziness. I pointed it out to my Dad. I’m sure if he’d ever seen one before but I might be wrong about that.

  15. About 7.3 million years ago, a triple star system named Algol passed within 9.8 light years of the Sun. Although it may not seem like a very close approach, Algol has a combined mass that is 5.8 times the mass of the Sun. In addition, the combined luminosity of Algol is a whopping 100 times the luminosity of the Sun. At closest approach, the gravity from Algol might have been sufficient to perturb the Oort cloud. An observer on Earth at that time would have seen Algol shining as a brilliant star with a visual magnitude of about -2.8. That is over 3 times brighter than Sirius appears at present. Currently, Algol is about 93 light years away.

    http://beyondearthlyskies.blogspot.com/2013/04/nearest-stars-past-present-and-future.html

    Similar interesting reading: http://www.rssd.esa.int/hipparcos/venice-proc/poster05_21.pdf

  16. Other suggestions for disruption of the Oort Cloud in the past, may be the Neptune Uranus system perturbations, which may be due to solar system changes.
    Pitchin a few to the Saturn Jupiter system, hey, think fast..catch..oops..just kiddin..ha

  17. I think ISON was interesting because it was thought to be the first time it visited the inner system. Seems pretty small for a first timer. A bunch of the known KBOs are pretty large. Nobody has seen an Oort Cloud object yet that I know of.

    SOHO has found a bunch of sungrazers. The Kreutz Group which are though to be fragments of a single comet that fragmented in 371 BC numbers over 1400 members. Average orbital period is around 350 years. Some hit the sun. Some don’t. Some survive perihellion. Some don’t.

    First and best comet I saw was a Kreutz Group member called Ikeya – Seki in 1965. Visible in the Northern hemisphere. Got as bright as -10 magnitude. At the time, I thought comets were way cool. Now they worry me. Cheers –

    http://www.ast.cam.ac.uk/~jds/kreutz.htm

    http://www.fallofathousandsuns.com/comet-ikeya-seki.html

  18. any possibility ISON caused the earth to reverse its rotation without anyone noticing? lol.

    4:05 Youtube: Climate change the state of the science (data visualization) .
    International Geosphere-Biosphere Programme
    Published on Nov 19, 2013
    Produced by the International Geosphere-Biosphere Programme and Globaia and funded by the UN Foundation.
    The data visualization summarises and visualizes several of the most significant statements in the Intergovernmental Panel on Climate Change’s (IPCC) recent Fifth Assessment Report, (Working Group I summary for policymakers, the Physical Science Basis).

  19. Probably the inner rings of the Oort Cloud ..

    Wiki has a nice little orbital definition for ISON..and its probable origins..

    http://en.wikipedia.org/wiki/C/2012_S1

    Comet ISON came to perihelion (closest approach to the Sun) on 28 November 2013 at a distance of 0.0124 AU (1,860,000 km; 1,150,000 mi) from the center point of the Sun.[2] Accounting for the solar radius of 695,500 km (432,200 mi), Comet ISON passed approximately 1,165,000 km (724,000 mi) above the Sun’s surface.[23] Its trajectory appeared to be hyperbolic, which suggested that it was a dynamically new comet coming freshly from the Oort cloud.[24][25] Near perihelion, a generic heliocentric two-body solution to the orbit suggests that the orbital period was around 400,000 years.[26] But for objects at such high eccentricity, the Sun’s barycentric coordinates are more stable than heliocentric coordinates.[27] The orbit of a long-period comet is properly obtained when the osculating orbit is computed at an epoch after leaving the planetary region and is calculated with respect to the center of mass of the Solar System. Using JPL Horizons, the barycentric orbital elements for epoch 1 January 2050 generate a hyperbolic solution.[3] On its closest approach, Comet ISON passed about 0.07248 AU (10,843,000 km; 6,737,000 mi) from Mars on 1 October 2013, and the remnants of Comet ISON will pass about 0.43 AU (64,000,000 km; 40,000,000 mi) from Earth on 26 December 2013.[28]

    Shortly after its discovery, similarities between the orbital elements of Comet ISON and the Great Comet of 1680 led to speculation that there might be a connection between them.[29] Further observations of ISON, however, showed that the two comets are not related.[30]

    Earth will pass near the orbit of Comet ISON on 14–15 January 2014, well after Comet ISON has passed, at which time micron-sized dust particles blown by the Sun’s radiation may cause a meteor shower or noctilucent clouds;[31][32] however, both events are unlikely. Because Earth only passes near Comet ISON’s orbit, not through the tail, the chances that a meteor shower will occur are slim.[33] In addition, meteor showers from long-period comets that make just one pass into the inner solar system are very rare, if ever recorded.[34] The possibility that small particles left behind on the orbital path—almost one hundred days after the nucleus has passed—could form noctilucent clouds is also slim. No such events are known to have taken place in the past under similar circumstances.[34]

  20. The rest of their “it could happen” statements are just as valid as the direction of the earth’s rotation. Someone should be very embarrassed and someone should ask for their money back.

  21. I don’t know if I am being paranoid, but it seems COLA have decided to remove ALL the temperature anomaly maps because it ain’t fitting the agenda. Steven Goddard etc frequently uses them to point out global cooling etc.

    http://wxmaps.org/pix/clim.html

    The have been removed or not available for about 8 days now especially with the cold in USA and EUROPE where most of the AGW clients live. Maybe I have an access problem but I doubt it please confirm others here.

  22. At 2:54 in this video;
    “2009 is the first year of global governance with the G20 in the middle of the financial crisis. The Climate conference in Copenhagen is another step toward the global management of our planet.”
    Herman Van Rompuy is the first full-time President of the European Council.

    How’s that NWO thing working out for you Herman?

    Did we ever find out who the Climategate whistleblower was?

  23. This describes James Hansen’s last 60 hrs and last 40 years of his career! How could anyone like him give a legitimate lecture on the “Frontier of Geophysics” when his life’s work demonstrates a profound misunderstanding of anything regarding geophysics or anything about science even in the most dumbfounded of ways!

    Can’t blame it on Vietnam and Agent Orange Jimmy Boy.

    Ha

  24. ISON is just one in a long series of comets heralded as the one of the century but which turn out a damp squib, comet Kohoutek being the archetypical example. Discovered at great distance and then “predicted” an eye-watering brightness at perihelium. These predictions are usually made using a rule derived from the brightness development of other comets, Halley for instance. What is then forgotten is that the behaviour of recurrent comets, which have gone through several perihelion passages and therefore gone through the cycle of outgassing and refreezing several times, can be completely different from that of sporadic comets who are first timers. For a start, most comets we know the orbit of are periodic ones and have already been selected for surviving the first passage, which strongly biases their characteristics. Most newcomers simply perish and ISON will not have been the last one.

  25. [Snip. URL removed. You cannot come into Anthony's home on the internet and insult and attack him. Get rid of the URL or go away. — mod.]

  26. Comet Hale-Bopp in ’97 was a stunner. I’d a daily 20 mile pre-dawn drive along motorway headed north-west and just about for an entire month the skies were clear, affording spectacular views. These things can really shift and sure enough, it did vamoos. Anyone got info on its current whereabouts?

  27. ***
    Gunga Din says:
    December 12, 2013 at 4:25 pm

    I’ve only seen one comet with the my naked eye. I think it was Hyakutake in 1996.
    It was bright enough that I could see it in a restaurant parking lot in the city. It looked kind of a seed from a cottonwood tree. No tail per say but an off-center fuzziness.

    ***

    When I saw Hyakutake in 1996, the nucleus was a fuzzy ball, but the faint tail stretched out an amazing distance, prb’ly 50+ deg of sky. If you looked directly at it, it was hard to see, but averted vision made it look spectacular & a quite spooky…

  28. Eliza, I find the COLA maps this morning, including the anomaly maps. But they don’t say much about trends anyway, so not sure what purpose they would serve either side.

  29. To u.k.(us):

    Look up the term “proper motion”. This is the angular component
    of velocity of a star relative to the Solar system. Adding in radial
    motion (much harder to measure), it’s been estimated that the
    star Wolf 424 has an actual velocity of approximately 555 kilometers
    per second. This would lead to it clipping off a distance of one
    light-year in a mere 540 years. Thus, over a time frame of several
    millions of years, this star could cover 1000’s of light-years. Other
    stars have slower motions, but it’s quite conceivable that a number
    of stars could have passed relatively close to the Solar system over
    that time span.

    Beyond that, the mostly postulated Oort cloud is bound to the Sun
    only very weakly. Even at the 1 AU of the Earth’s orbit, the acceleration
    from the Sun’s gravity that holds the Earth in its orbit is only about
    0.006 meters/second/second. At a distance of, say, 5200 AU, that
    would be a factor of 27 million weaker, or only about
    2 x 10^-10 meters/second/second. So a star of Sol’s mass passing
    within 10000 AU of our postulated object 5200 AU out in the Oort
    cloud would have a gravitational influence of about 1/4 as much as
    Sol’s gravity–easily enough to significantly alter its orbit.

    So, as incredible as it may sound, you shouldn’t have any difficulty
    believing that a “passing star millions of years ago” could have
    perturbed comet ISON from what would have been a peaceful
    life in the Oort cloud and sent it plunging wildly inward toward
    its recent close rendezvous with the Sun.

  30. boris says:
    December 12, 2013 at 3:35 pm
    Any rumors of rock shards of Ison heading for Earth yet?

    I took a bit of interest in this back in September, using my own hand-made Newtonian simulation model, and NASA state vectors. I reckoned That, if Ison broke apart, most of the outbound debris field would pass a long way from Earth, but there was a very slim outside chance of some impacting Earth between the end of December 2013 and mid January 2014.

    There have also been predictions made that on 15 Jan 2104 the Earth would pass through the debris trail left by Ison when it was inbound earlier this year. I looked at that too using my model, and didn’t think we’d be anywhere near it.

    Anyway, I don’t plan on staying awake on 15 Jan 2014. Or any time over the previous two weeks.

    • Frank Davis,

      You remind me – it’s been several years since a “The World will End on XX/YY/ZZZZ” pediction. “Where have all the prophets gone? Long time pa-a-ssing …” Too small profits for prophets?

  31. Brians356, there are still plenty of prophecies of doom surrounding Ison.

    I really think that there are people who can’t sleep at night unless they’re convinced that the world is going to end tomorrow or next week or next year.

    It never, ever, ever stops.

    • Well, I guess I meant there has been no idiotic news fixation on some long-bearded saffron- robed figure surrounded by pretty nymphs of late. I guess the zombie idiocy is a proxy.

Comments are closed.