Chiron

/kuy"ron/, n.

1. Class. Myth. a wise and beneficent centaur, teacher of Achilles, Asclepius, and others.

2. Astron. an asteroid located between Saturn and Uranus, about 100 mi. (160 km) in diameter: discovered in 1977.

Also, Cheiron.

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I

Comet once thought to be the most distant known asteroid.

Discovered in 1977, it travels in an unstable, eccentric orbit between those of Saturn and Uranus. In 1989 astronomers detected a fuzzy cloud (coma) around Chiron. Because such a cloud is a defining feature of comets, Chiron was reclassified as a comet. See also Centaur object.

II

In Greek mythology, one of the Centaurs.

The son of Cronus and the sea nymph Philyra, he lived at the foot of Mount Pelion in Thessaly and was renowned for his wisdom and his knowledge of medicine. He was the teacher of many Greek heroes, including Achilles, Heracles, Jason, and Asclepius. Wounded accidentally by a poisoned arrow shot by Heracles, he was in such agony that he surrendered his immortality in order to die. Zeus placed him among the stars as the constellation Sagittarius.

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▪ Greek mythology

      in Greek mythology, one of the Centaurs, the son of the Titan Cronus and Philyra, an Oceanid or sea nymph. Chiron lived at the foot of Mount Pelion in Thessaly. Unlike other Centaurs, who were violent and savage, he was famous for his wisdom and knowledge of medicine. Many Greek heroes, including Heracles, Achilles, Jason, and Asclepius, were instructed by him. Chiron frequently appears in the legends of his grandson, Peleus, and his great-grandson, Achilles. 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.

▪ astronomy

      icy small body orbiting the Sun in the outer solar system. Once thought to be the most distant known asteroid, it is now believed to have the composition of a comet nucleus—i.e., a mixture of water ice, frozen gases, and dust.

      Chiron was discovered in 1977 by the American astronomer Charles Kowal and classified as an asteroid with the number 2060. It is about 200 km (125 miles) in diameter and travels in an unstable, eccentric orbit between the orbits of Saturn and Uranus with a period of about 50.7 years. In 1989 two other Americans, Karen J. Meech and Michael Belton, detected a fuzzy luminous cloud around Chiron. Such a cloud, termed a coma and being a distinguishing feature of comets, consists of dust and entraining gases expelled from the cometary nucleus when sunlight vaporizes its ices. On the basis of this discovery, Chiron was reclassified as a comet. Subsequently, additional asteroid-size icy bodies in orbits similar to that of Chiron were discovered and given the class name Centaur objects (Centaur object).

Armand H. Delsemme

 

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