The Columbia Encyclopedia, Sixth Edition. 2001-07.
Trojan asteroids
two groups of asteroids that revolve about the sun in the same orbit as Jupiter; one group is about 60° ahead of the planet in the orbit, the other about 60° behind it. In 1990, a similar asteroid, Eureka, was found in the orbit of Mars. Some of the Trojan asteroids are composed of ice and dirt, rather than rock, making it possible that they are captured comets. The Trojan asteroids represent one possible special solution to the famous three-body problem (see celestial mechanics), with each group forming an equilateral triangle with Jupiter and the sun. The first Trojan asteroid discovered was Achilles, observed in 1904 by the German astronomer Max Wolf; all of these asteroids are named for heroes of the Trojan War.
