This is an artist's concept of a comet dust trail and dust tail. The trail can only be seen in the light of radiated heat. The dust trail is made of particles that are the size of sand grains and pebbles. They are large enough that they are not affected much by the Sun's light and solar wind. The dust tail, on the other hand, is made of grains the size of cigarette-smoke particles. These grains are blown out of the dust coma near the comet nucleus by the Sun's light.
NASA Ames Research Center/K. Jobse, P. Jenniskens
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