In the early hours of Nov. 27, 2013, Comet ISON entered the field of view of the European Space Agency/NASA Solar and Heliospheric Observatory. In this picture, called a coronagraph, the bright light of the Sun itself is blocked so the structures around it are visible. The comet is seen in the lower right; a giant cloud of solar material, called a coronal mass ejection or CME, is seen billowing out under the Sun.
Comet ISON, which began its trip from the Oort cloud region of our solar system, will reach its closest approach to the Sun on Thanksgiving Day, skimming just 730,000 miles above the sun's surface.
Image Credit: ESA/NASA/SOHO
Explanation from: http://www.nasa.gov/content/comet-ison-streams-toward-the-sun/#.Upcm4cR5MlA