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Coma

13:31

A Comet With a Coma Five Times Greater than Jupiter is Approaching the Earth

8:41

Introduction to Comets - How They Form and How Comets Work

3:46

The man woke up from a 19-year coma and What he told disturbed everyone

3:19

HUGE ASTEROID CAPTURED IN COMET ISON'S COMA ???

3:44

Less Than Five - What's the Difference Between Comets, Asteroids, Meteoroids, Meteors & Meteorites?

The coma is the nebulous envelope around the nucleus of a comet, formed when the comet passes near the Sun in its highly elliptical orbit. As the comet warms, parts of it sublimate; this gives a comet a diffuse appearance when viewed through telescopes and distinguishes it from stars. The word coma comes from the Greek κόμη (kómē), which means "hair" and is the origin of the word comet itself.