Hubble Sees Comet ISON   
       
   April 24, 2013: Later this year, Comet ISON is expected to become a naked-eye   
   object when it skims through the atmosphere of the sun.  The Hubble Space   
   Telescope has just obtained a sneak preview.   
       
   Hubble photographed ISON on April 10th.  At the time, the comet was 386   
   million miles from the sun (394 million miles from Earth), just inside the   
   orbit of Jupiter. Even at that great distance the comet is already active as   
   sunlight warms the surface and causes frozen gases to vaporize. A detailed   
   analysis of the image reveals a strong jet blasting dust particles off the   
   sunward-facing side of the comet's nucleus.   
       
   http://www.youtube.com/watch?v=_eSYxvUWwVk   
       
   Hubble's view of Comet ISON (C/2012 S1) on April 10, 2013. This image was   
   taken in visible light. The blue false color was added to bring out details in   
   the comet structure. Credit:NASA, ESA, J.-Y. Li (Planetary Science Institute),   
   and the Hubble Comet ISON Imaging Science Team Astronomers are using Hubble   
   images to measure the activity level of the comet and constrain the size of   
   its icy nucleus. Preliminary measurements  suggest that the ISON's nucleus is   
   no larger than three or four miles (~5 to 6 km) across. This is remarkably   
   small considering the high level of activity observed in the comet so far,   
   said researchers.   
       
   The comet's dusty atmosphere, or "coma", is approximately 3,100 miles across,   
   or 1.2 times the width of Australia. A dust tail extends more than 57,000   
   miles, far beyond Hubble's field of view.   
       
   A more careful analysis is  underway to improve these measurements and to   
   predict the comet's activity when it skims 700,000 miles above the sun's   
   roiling surface on November 28.   
       
   For updates, stay tuned to Science@NASA.   
       
   Credits:   
       
   Production editor: Dr. Tony Phillips | Credit: Science@NASA   
       
   More information:   
       
   Comet ISON Meteor Shower  -- a video from Science@NASA   
       
   Comet of the Century?  -- experts discuss how bright Comet ISON might become   
   when it skims the sun in late 2013.   
       
   ISON stands for International Scientific Optical Network, a group of   
   observatories in ten countries who have organized to detect, monitor, and   
   track objects in space. ISON is managed by the Keldysh Institute of Applied   
   Mathematics, part of the Russian Academy of Sciences.   
       
       
   Regards,   
       
   Roger   
      
   --- D'Bridge 3.92   
    * Origin: NCS BBS - Houma, LoUiSiAna (1:3828/7)