Sungrazing comets are comets that pass very close to the sun, sometimes to within a few thousand miles of its surface.
The Solar and Heliospheric Observatory (SOHO) is a joint NASA/ESA mission to probe the corona, or outer layer of the sun's atmosphere. The spacecraft became operational in May 2006. Owing to its constant study of the sun, SOHO is the leader in spotting sungrazing comets, having recorded around 3,000 as of Sepp. 13, 2015.