Wikipedia
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.
Usage examples of "comet tail".
Gordie imagined he could see shock waves in the comet tail -- but that was probably imagination.
Within one hour it was a comet tail ten thousand miles long, which visibly brightened the daytime heavens.
They veered all at once, and drove in toward the retreating comet tail of the pyropod he had wounded.
Then everything was again still on the ship, until the next striking of grains from a meteorite or comet tail, when the operation of renewing the protective shield was repeated exactly.
But the lake monster swept through the dust, and the dust followed her like a comet tail.