Comet tail

From Wikipedia, the free encyclopedia

A comet tail—and coma—are features visible in comets when they are illuminated by the Sun and may become visible from Earth when a comet passes through the inner Solar System. As a comet approaches the inner Solar System, solar radiation causes the volatile materials within the comet to vaporize and stream out of the nucleus, carrying dust away with them. Separate tails are formed of dust and gases, becoming visible through different phenomena; the dust reflects sunlight directly and the gases glow from ionisation. Most comets are too faint to be visible without the aid of a telescope, but a few each decade become bright enough to be visible to the naked eye.

Diagram of a comet showing the dust tail, the dust trail (or antitail) and the ion gas tail, which is formed by the solar wind flow.
Comet Lovejoy photographed in 2011 by astronaut Dan Burbank from the International Space Station
Comet Holmes (17P/Holmes) in 2007 showing blue ion tail on right
Animation of a comet's tail