Comet Hale-Bopp
(Date of photograph unknown)
Comet Hale-Bopp. Time-exposure optical image of comet Hale-Bopp, as seen from the orbiting space shuttle Columbia at sunset. The ball of gas (coma) around the comet's nucleus is brighter than the long, extended tail. A comet is a ball of ice and dust that orbits the Sun. As it passes near the Sun its surface evaporates, releasing a tail of dust and vapour that can be millions of kilometres in length. The tail always extends in the opposite direction to the Sun, whatever direction the comet is travelling in. Hale-Bopp was discovered on 23 July 1995 and was brightest over Earth in March 1997. Image taken during mission STS-83 (4-8 April 1997).