What are the icy objects with huge trials that orbit sun?

The icy objects with huge trails that orbit the Sun are called comets. Comets are composed mostly of ice and dust, and when they approach the Sun, the heat from the Sun causes the ice to vaporize and the dust to be blown away from the nucleus, creating a tail that can be millions of kilometers long. Comets are believed to originate in the Kuiper Belt, a region of the outer solar system beyond the orbit of Neptune, and the Oort Cloud, a region of the solar system that extends far beyond the orbit of Pluto.