ANATOMY OF A COMET
Four basic components give a comet its characteristic appearance
COMA
Up to 65,000 miles in diameter, this contains dust and gases released by the nucleus.
NUCLEUS
The solid part, a few miles or tens of miles across, made up of dust, ice and other frozen chemicals.
PLASMA TAIL
Maybe ten times as long as the gas tail, the ionised particles here are blown by the solar wind.
DUST TAIL
As much as 6 million miles long, this is blasted out from the coma by the pressure of solar radiation.