Comets are icy objects which travel through the Solar System. A bright comet in the night sky looks like a hazy patch with a long wispy tail. Comets travel in orbits through the Solar System.They evaporate gas and dust and grow long tails when they are near enough to the Sun's heat and light.
The tails always point away from the Sun, blown by the light and streams of atomic particles from the Sun. the most famous comet, Halley's Comets, can be seen from the Earth every 76 years.