CHIRON

in Greek mythology, one of the Centaurs, the son of the god Cronus and Philyra, a sea nymph. Chiron lived at the foot of Mount Pelion in Thessaly and was famous for his wisdom and knowledge of medicine. Many Greek heroes, including Heracles, Achilles, Jason, and Asclepius, were instructed by him. Accidentally pierced by a poisoned arrow shot by Heracles, he renounced his immortality in favour of Prometheus and was placed among the stars as the constellation Sagittarius. comet, once thought to be the most distant known minor planet. It was discovered in 1977 by Charles Kowal, an American astronomer, at the Palomar Observatory in southern California. Chiron travels in an unstable, eccentric orbit between the orbits of Saturn and Uranus. It measures 200-300 km (120-190 miles) in diameter. In 1989 astronomers detected a cloud of particles around Chiron. Such a dusty envelope is considered to be a distinguishing feature of comets. On the basis of this discovery, Chiron was reclassified from an asteroid to a comet.