What is comets

What are comets. 

Comets are beautiful bodies in the solar system with a distinct head and luminous tail moving across the sky. 

These are the heavenly bodies which revolve around the sun in an elliptical path. They take a very long time to complete one revolution around the sun. They appear in the sky like a ball of fire with a long tail.  They move high velocity. The tail of the comet always points away from the sun. 

The most famous comet is called Halley's comet. It appears in the sky after a cycle of 76 years. It last appeared in the year 1986.