Comets

Comets are a frozen rock which contains dust and ice. They have a highly elliptical orbit around the Sun. 

The solar radation emitted from the Sun, forms a solar wind which melts the ice on the comet, causing it to form a tail, which always points away from the Sun.

When the comet goes into deep space it will refreeze. 

Due to the Sun’s gravity the Comet moves faster when it is nearer the Sun and slower when further from the Sun.