Video: What is a Sungrazing Comet?

A brief video (just over three minutes) discussing "sungrazer" comets, including example footage from past observations by spacecraft. Sungrazing comets 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 (1.37 million kilometers) from the sun at perihelion. Many come even closer, even to within a few thousand miles.

Comet ISON came within about 730,000 miles (1.17 million kilometers) of the Sun on November 28, 2013. During its close approach to the Sun, ISON was observed by several members of NASA's heliophysics mission fleet. These spacecraft have often indirectly supported comet-hunting efforts, too, including the joint-European Space Agency/NASA Solar and Heliospheric Observatory (SOHO).

NASA has also run a citizen science program since the early 2000s called "Project Sungrazer." This program allows amateur astronomers to process images gathered by SOHO. Their work has helped scientists to discover more than 5,000 new comets as they approach the Sun and vent gas and dust into space. In fact, over half of all known comets were first discovered by Sungrazer Project contributors! These comet discoveries have shaped our modern understanding of comet orbits, composition, dust properties, evolution, and fragmentation.