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What is a Sungrazing Comet?

Sungrazing comets are a special class of comets that come very close to the sun at their nearest approach, a point called perihelion. To be considered a sungrazer, a comet needs to get within about 850,000 miles from the sun at perihelion. Many come even closer, even to within a few thousand miles.

Being so close to the sun is very hard on comets for many reasons. They are subjected to a lot of solar radiation which boils off their water or other volatiles. The physical push of the radiation and the solar wind also helps form the tails. And as they get closer to the sun, the comets experience extremely strong tidal forces, or gravitational stress. In this hostile environment, many sungrazers do not survive their trip around the sun. Although they don't actually crash into the solar surface, the sun is able to destroy them anyway.

Many sungrazing comets follow a similar orbit, called the Kreutz Path, and collectively belong to a population called the Kreutz Group. In fact, close to 85% of the sungrazers seen by the SOHO satellite are on this orbital highway. Scientists think one extremely large sungrazing comet broke up hundreds, or even thousands, of years ago, and the current comets on the Kreutz Path are the leftover fragments of it. As clumps of remnants make their way back around the sun, we experience a sharp increase in sungrazing comets, which appears to be going on now. Comet Lovejoy, which reached perihelion on December 15, 2011 is the best known recent Kreutz-group sungrazer. And so far, it is the only one that NASA's solar-observing fleet has seen survive its trip around the sun.

Comet ISON, an upcoming sungrazer with a perihelion of 730,000 miles on November 28, 2013, is not on the Kreutz Path. In fact, ISON's orbit suggests that it may gain enough momentum to escape the solar system entirely, and never return. Before it does so, it will pass within about 40 million miles from Earth on December 26th. Assuming it survives its trip around the sun.

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Other multimedia items related to this story:
     Kreutz Comet Orbits (id 4018)
     SDO Sees Comet Lovejoy Survive Close Encounter With Sun (id 10886)
     Sungrazers Galore (id 11156)
     Sun Grazing Comets as Solar Probes (id 11158)
     The Path of Comet ISON (id 11222)
More information on this topic available at:
http://www.nasa.gov/content/goddard/timeline-of-comet-ison-s-dangerous-journey/

Short, narrated video about sungrazing comets. Watch this video on the NASAexplorer YouTube channel.    Short, narrated video about sungrazing comets.

Watch this video on the NASAexplorer YouTube channel.

For complete transcript, click here.
Duration: 3.1 minutes
Available formats:
  1280x720 (59.94 fps) QT         3 GB
  1280x720 (59.94 fps) QT         1 GB
  1280x720 (29.97 fps) QT         245 MB
  1280x720 (29.97 fps) QT         112 MB
  1280x720 (29.97 fps) WMV         98 MB
  1280x720 (29.97 fps) MPEG-4   81 MB
  960x540 (29.97 fps) MPEG-4   89 MB
  640x360 (29.97 fps) MPEG-4   35 MB
  320x240 (29.97 fps) MPEG-4   18 MB
  1280x720   PNG           782 KB
  320x180     JPEG         12 KB
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Short URL to This Page:http://svs.gsfc.nasa.gov/goto?11307
Animation Number:11307
Completed:2013-07-13
Video Editor:Scott Wiessinger (USRA)
Producer:Scott Wiessinger (USRA)
Writers:Karen Fox (ASI)
 Scott Wiessinger (USRA)
Series:Narrated Movies
Goddard TV Tape:G2013-050 -- Sungrazing Comet Primer
Please give credit for this item to:
NASA's Goddard Space Flight Center
 
Keywords:
SVS >> CME
SVS >> Comet
SVS >> Coronal Mass Ejection
SVS >> HDTV
SVS >> SOHO
SVS >> Solar Ultraviolet
SVS >> Solar Wind
SVS >> Sun
SVS >> SDO
SVS >> Comet Encke
SVS >> Solar Dynamics Observatory
SVS >> Heliophysics
SVS >> STEREO
SVS >> Corona
SVS >> Sungrazer
SVS >> Sungrazing Comets
 
 


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Many of our multimedia items use the GCMD keywords. These keywords can be found on the Internet with the following citation:
Olsen, L.M., G. Major, K. Shein, J. Scialdone, S. Ritz, T. Stevens, M. Morahan, A. Aleman, R. Vogel, S. Leicester, H. Weir, M. Meaux, S. Grebas, C.Solomon, M. Holland, T. Northcutt, R. A. Restrepo, R. Bilodeau, 2013. NASA/Global Change Master Directory (GCMD) Earth Science Keywords. Version 8.0.0.0.0

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