what are comet tails are made mostly of?

Answer 1

Comets are believed to have originated in the Oort Cloud (named for anstronomer named Oort). The Cloud exists outside the solar nebula and is made up of water in a solid state and other debris that was leftover when the universe came into being.

The comet, itself, is like a small planet that travels in an eliptical orbit around the Sun. The effect of solar radiation on the comet's "coma" (thin atmosphere) causes some of the material to separate and fall away, behind the comet, leaving a "tail." The tail is visible to us when the comet comes relatively close to the earth and the sun's light is reflected from the ice in its tail.

Answer 2

Mostly bits of ice, dust, small particles of rock from asteroids, and other intergalactic detritus.
Hard to believe that something made up of such mundane ingredients could look so spectacular crossing the sky, isn't it?

Answer 3

frozen peices of debris flyingt from the comets end, or other debris the comet runs into
.

Answer 4

ice