A comet is basically a big ball of ice and rock.
Where do they come from?
They are leftovers from the beginning of the solar system.
Why dose a Comet have a Tail
As a comet approaches and get close to the sun it starts spewing dust and gas. This debris forms a tail which is the image we are familiar with, the tail will always point away from the sun. The main reason for this is because the sun's heat and radiation.
The heat and radiation from the sun produce a wind called the Solar Wind, when a comet gets close it's starts to melt.
The only solid part of any comet is in the middle or nucleus.
It's said that the Greek philosopher Aristotle gave them the name comet from the Greek word meaning ‘hair of the head’
Pictures of Comets