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.
Comets are called sungrazers when they pass within 850,000 miles (1.38 million km) of the sun’s surface.
Small sungrazers can be shattered or totally evaporated by the sun’s heat and tidal forces. Other sun-
grazers can survive many close passes.
Eighty percent of comets captured by SOHO's instruments travel along the Kreutz path, a single orbit that takes 800 years to complete. These Kreutz comets are fragments from a single large comet that was shattered thousands of years ago. The far end of the Kreutz path lies 160 times farther from the sun than the orbit of Earth.