Trojan asteroids

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 .

Trojan asteroid A member of one of two groups of asteroids, at a mean distance of 5.2 AU from the Sun, which share the orbit of Jupiter. They lie clustered around the leading (L₄) and following (L₅) Lagrangian points, 60 ° ahead of and behind Jupiter. Perturbations by other planets cause the Trojans to oscillate along the orbit of Jupiter about 45–80 ° from the planet, taking 150–200 years per cycle. The first Trojan to be discovered was Achilles in 1906. Over 2000 Trojan asteroids are now known, 55 % in the leading (L₄) group. In 1990 the first Martian Trojan, (5261) Eureka, was discovered in the L₅ region of Mars's orbit, and in 2001 the first Neptunian Trojan (2001 QR₃₂₂) was discovered at Neptune's leading Lagrangian point.