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Comet Hale-Bopp

Comet C/1995 O1 Hale-Bopp, Great Comet of 1997

One of the most significant comets in recent years, this object was discovered independently by two observers - Alan Hale and Thomas Bopp - on 23 July 1995. Following convention, it was given both their names, hence the hyphenated comet name 'Hale-Bopp'.

Over the following two years, the comet passed through the inner Solar System to reach perihelion on 1 April 1997. During this approach it displayed a double cometary tail, with one blue tail of gas streaming directly away from the Sun, and another composed of debris left in the comet's wake. The nucleus of the comet was found to be unusually large, with a diameter of some 60km. It has been suggested that Hale-Bopp has a double nucleus, consisting of two gravitationally-bound bodies rather than a single core, but this has not been definitively established.

The comet remained visible to the naked eye for more than eighteen months, an extraordinarily long time for any comet, and as it approached its perihelion point, it was among the brightest objects in the sky before receding as it plunged on into the depths of the Solar System.

Comet Hale-Bopp follows a long orbit around the Sun. It has already passed well beyond the distance of Neptune's orbit, and will travel out to a distance of more than 370 AU (nearly four times the distance of the Kuiper Belt's outer edge) before it begins its inward journey toward the Sun once again.

The entire orbit takes a period of some 2,533 years, and is notable for its extreme inclination to the plane of the Solar System. Probably due to an near-collision with Jupiter on a previous visit to the inner system, this orbit is tipped almost perpendicularly to the Ecliptic plane. The comet is currently in the far southern constellation of Octans, following a trajectory almost towards the Southern Celestial Pole, and well outside the plane of the planets' orbits around the Sun.