Comet C/1995 O1 (Hale–Bopp) was discovered simultaneously by the two American amateur astronomers Alan Hale and Thomas Bopp on 23 July 1995. At that time, it was at 7.1 AU from the Sun and had already a total visual magnitude of 10, which is more than 100 times brighter than COMET HALLEY at the same distance. It passed perihelion on 1 April 1997, at 0.91 AU from the Sun