A comet feature is the TAIL of a comet, which is made up of gas and dust that is released from the nucleus of the comet. The TAIL of a comet is usually visible when the comet is close to the sun, as the heat causes the gas and dust to be released. The TAIL of a comet can be seen pointing away from the sun, and can stretch for millions of miles. The TAIL of a comet is often referred to as its 'comet feature'.