What Happened to Comet ISON?   
       
   Dec. 4, 2013:  Astronomers have long known that some comets like it hot.   
   Several of the greatest comets in history have flown close to the sun, puffing   
   themselves up with solar heat, before they became naked-eye wonders in the   
   night sky.   
       
   Some comets like it hot, but Comet ISON was not one of them.   
       
   The much-anticipated flyby of the sun by Comet ISON on Thanksgiving Day 2013   
   is over, and instead of becoming a Great Comet...   
       
   "Comet ISON fell apart," reports Karl Battams of NASA's Comet ISON Observing   
   Campaign. "The fading remains are now invisible to the human eye."   
       
   At first glance this might seem like a negative result, but Battams says   
   "rather than mourn what we have lost, we should perhaps rejoice in what we   
   have gained-some of the finest data in the history of cometary astronomy."   
       
   On the morning of Nov. 28th, expectations were high as ISON neared perihelion,   
   or closest approach to the sun. The icy comet already had a riotous tail 20   
   times wider than the full Moon and a head bright enough to see in the pre-dawn   
   sky with the unaided eye. A dose of solar heat could transform this good comet   
   into a great one.   
       
   During the flyby, more than 32,000 people joined Battams and other solar   
   scientists on a Google+ Hangout. Together they watched live images from a   
   fleet of solar observatories including the twin STEREO probes, the Solar   
   Dynamics Observatory, and SOHO. As Comet ISON approached the sun it brightened   
   and faded again.   
       
   "That might have been the disintegration event," says Matthew Knight of NASA's   
   Comet ISON Observing Campaign.   
       
   http://www.youtube.com/watch?v=BPHR-34MstE   
       
   A highlight of Comet ISON's approach to the sun was this conjunction between   
   Comet Encke and Comet ISON recorded by NASA's STEREO-A spacecraft. Credit:   
   NASA/STEREO/Rob Matson   Movie   
       
   Cameras onboard the Solar Dynamics Observatory followed the comet all the way   
   down to perihelion and saw... nothing.   
       
   "We weren't sure what was happening," recalls Knight.  "It was such a roller   
   coaster of emotions."   
       
   The researchers were surprised again when a fan-shaped cloud emerged from the   
   sun's atmosphere. No one knows for sure what was inside. Possibilities include   
   a remnant nucleus, too small for SDO to detect, or a "rubble pile" of   
   furiously vaporizing fragments. By the end of the day, Comet ISON was nothing   
   but a cloud of dust.   
       
   "It's disappointing that we didn't get a spectacular naked eye comet," says   
   Knight, "but in other ways I think Comet ISON was a huge success. The way   
   people connected with Comet ISON via social media was phenomenal; our Comet   
   ISON Observing Campaign website earned well over a million hits; and I had   
   trouble downloading images near perihelion because NASA's servers were   
   swamped."   
       
   "So maybe ISON was the 'Comet of the New Century,'" he says.   
       
   Battams agrees:  "The comet may be dead, but the observing campaign was   
   incredibly successful." Since its discovery in Sept. 2012, Comet ISON has been   
   observed by an armada of spacecraft, studied at wavelengths across the   
   electromagnetic spectrum, and photographed by thousands of telescopes on   
   Earth.  For months at a time, uninterrupted, someone or some spacecraft had   
   eyes on the comet as it fell from beyond the orbit of Jupiter to the doorstep   
   of the sun itself. Nothing was missed.   
       
   The two astronomers hope that the wealth of data will eventually allow them   
   and their colleagues to unravel the mystery of exactly what happened to Comet   
   ISON.   
       
   "This has unquestionably been the most extraordinary comet that Matthew and I,   
   and likely many others, have ever witnessed," says Battams. "The universe is   
   an amazing place and it has just amazed us again."   
       
   Credits:   
   Author: Dr. Tony Phillips | Production editor: Dr. Tony Phillips | Credit:   
   Science@NASA   
       
   More information:   
       
   Comet ISON Observing Campaign   
       
       
   Regards,   
       
   Roger   
      
   --- D'Bridge 3.96   
    * Origin: NCS BBS - Houma, LoUiSiAna (1:3828/7)