ISON---Comet of the Century?

ISON---Comet of the Century?

They’re  calling it the Thanksgiving comet.  Could  Comet ISON be the comet of the century?  Since it was discovered by a pair of Russian amateur astronomers using the International Scientific Optical Network (ISON) in 2012, inquiring eyes have been on Comet ISON. If the comet survives its close encounter with the sun (perihelion) on November 28th, we could see an awesome sky show in early December.

ISON  would be closest to Earth on December 26,  passing by on its way back out to the outer regions of the solar system. For weeks, the comet could be visible all night long, and bright as Venus in daylight!

You can follow the progress of Comet ISON  and see some of the amazing pictures all over the internet. and  NASA are very good.  ISON has been an  impressive sight, brightening as it rushes toward the sun.

Sungrazing comets are not uncommon. Comet Lovejoy  in 2011  was a sungrazer, and it became a beautiful comet. But something like ISON has never happened before! Its size and hyperbolic trajectory suggests this is its first appearance from the outer regions of the Oort Cloud into the inner solar system.

The Oort Cloud is way out  beyond the orbit of Neptune.  It is made up of  billions of orbiting icy bodies believed to be fragments from the formation of the solar system.  Occasionally, there is a disturbance in the Oort Cloud, causing one of these bodies to fall into the inner solar system as a long-period comet.

ISON has been making this journey toward the sun for over 3 million years.

Periodic comets (Halley’s Comet, for example) have elliptical orbits; they come around again and again, making regular swings through the solar system.  Oort cloud comets like ISON have such extreme trajectories, it’s a one-time trip. They head back out into the black, never seen again.

At perihelion, the comet will be traveling at 248 miles per second, encountering solar temperatures of up to 5,000 degrees Fahrenheit!

Will ISON survive?  Keep up on the latest updates, and cheer on the comet at  EarthSky.

Whether ISON remains intact, breaks up, or  is completely  destroyed  during its encounter with the sun, for scientists, it has provided a rare opportunity to gather information about the  chemical composition of primordial comets and  the formation of the solar system. There  will be plenty of data to study for years to come.

Whatever happens, it’s going to be something to see.

I watched the fragments of  Comet Shoemaker-Levy-9  falling into Jupiter in 1994 on TV. ( There are videos on YouTube.) The images are astonishing, still.  It was the first observation of a collision in the solar system.  It was also an early example of the possibilities of the internet, as reports came in from observation sites around the world.

I will always remember Comet Hyakutake, in March of 1996.  Harry and I could see it even without binoculars from our own backyard.  It was a magnificent sight. They call it the Great Comet of 1996.

Will Comet ISON be one of the great ones?

UPDATE —As of 1:11 PM Thanksgiving Day, reports of ISON breaking up…

NASA Goddard’s Karl Battams has been keeping up with this comet via his Twitter feed @SunGrazerComets. Here’s what he had to say just  after perihelion—

Sungrazer Comets ‏@SungrazerComets5h

THIS > RT @RandomSpaceFact It is now clear that Comet #ISON either survived or did not survive, or… maybe both. Hope that clarifies things




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Filed under: seasons, weather

Tags: comets, ISON, Oort Cloud, sungrazer


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  • Now there is the debate whether it melted when it got close to the sun, or made it around. I haven't heard the latest development. Maybe they can send out Icarus to find it.

  • In reply to jack:

    Thanks for following along, Jack! What a glorious ride...According to the latest update from SungrazerComets on Twitter (2 hrs. ago) it does not look good....

    Sungrazer Comets ‏@SungrazerComets 2h
    I *do* think that something emerged from the Sun, but probably a v.small nucleus or "rubble pile", and I fear that may have now dissolved...

    Sungrazer Comets ‏@SungrazerComets 2h
    Comet #ISON really is fading fast and I no longer see any sign of a "central condensation" (i.e. no obvious indication of a nucleus...)

  • Thanks for the articulate, educational, and (still) fun post, Weather Girl. I hadn't known about the Oort cloud or its implications until you taught me about it.

  • Thank you so much for reading, MargaretSerious---I am so glad you enjoyed this post!

    Alas, it seems ISON is no more, but you never know. Maybe Hubble will be able to detect something in the coming days. ISON will live on,though. Many people--kids especially--have shared this wonder.

    And cold, clear nights = good seeing weather!

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