Comet DeVico. Optical CCD (Charge Coupled Device) image of Comet DeVico. The bright part (at centre left) is the nucleus of the comet whilst the tail stretches to far right. A comet is a ball of ice and dust on an elliptical orbit around the Sun. As it approaches the Sun its surface evapor- ates, releasing a tail of dust and vapour that can reach millions of kilometres in length. The tail always extends away from the Sun, whatever direct- ion the comet is travelling. This is because the dust is swept along by the solar wind, the stream of charged particles coming from the Sun. Photographed in November 1995 with a 35cm tele- scope at the OCA observatory in California, USA.