A group of minor planets that are clustered around two of the Lagrangian positions of the Jupiter-sun system; that is, a point in space at which a small body, under the gravitational influence of two large ones, will remain approximately at rest relative to them.

The first Trojan was Achilles, discovered in 1906.

These minor planets revolve around the sun in the Lagrangian points of Jupiter’s orbit and they 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 forty 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.