two groups of asteroids named for heroes of Greece and Troy in Homer's Iliad. These minor planets revolve around the Sun in the Lagrangian points of Jupiter's (Jupiter) orbit. These are positions where a small body can be held, by gravitational forces, at one point of an equilateral triangle whose other points are occupied by Jupiter and the Sun. About 40 Trojan planets are known; Achilles, the first, was discovered by Max Wolf in 1906. Of the named Trojans, Achilles, Hector, Nestor, Agamemnon, Odysseus, Ajax, Antilochus, Diomedes, and Menelaus are near the Lagrangian point 60° ahead of Jupiter. Patroclus, Priamus, Aeneas, Anchises, and Troilus are about 60° behind Jupiter.

The known Trojans undoubtedly rank among the larger asteroids but appear faint because of their great distance from the Earth. There are probably many smaller and even fainter members as yet undiscovered.