What are Trojan Asteroids and How are They Named?

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Trojan asteroids are small celestial bodies that gather at the L4 and L5 Lagrange points, located 60° ahead and behind Jupiter in its orbit. The first Trojan asteroid, 588 Achilles, was discovered in 1906 and named after characters from Homer's The Iliad, leading to the naming convention of "Greek group" for L4 and "Trojan group" for L5 asteroids. Each group traditionally includes one asteroid named after a character from the opposing side, creating a "spy" dynamic. The term "Trojan points" now applies to similar points around other celestial bodies, while "Trojan asteroids" specifically refers to those associated with Jupiter. Understanding these asteroids enhances knowledge of celestial mechanics and the history of astronomical naming conventions.
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Definition/Summary

A term referring to any of the small bodies that tend to collect at the L4 and L5 Lagrange points.

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Extended explanation

There are two stable points located 60° ahead and behind of Jupiter in its orbit where small astronomical objects tend to collect. These are Jupiter's L4 and L5 points.

The first of these objects was discovered by the astronomer Max Wolf in 1906 and named 588 Achilles. As subsequent objects were found they were also named after characters from Homer's The Illiad. Since this poem dealt with the Trojan war, these became to be known as Trojan asteroids, and the Jovian L4 and L5 points called Trojan points.

Convention has it that the asteroids located at L4 are named after Greek characters, making this the "Greek group" and the asteroids at L5 named after Trojan characters, making it the "Trojan group". However, before this convention became fully adopted, one asteroid in each group was named after a member of the opposing side, giving each camp a "spy" among the enemy.

The term "Trojan points" has since come to be used for the the L4 & L5 points of anybody and not just those of Jupiter, and "Trojan objects" for the objects located there. The term "Trojan Asteroid", however, still just refers objects at Jupiter's L4 and L5 points.

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