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Astro*Dictionary by Michael Erlewine





1 article for "Lagrangian Points"

Lagrangian Points [Astro*Index]

A set of 5 points derived from the analysis of the Restricted Three-Body Problem.

They mark the locations, in space, at which a body of negligible mass can remain in a stable orbit, despite the presence of the other two massive bodies. These points are named after the Italian-French astronomer and mathematician, Joseph Louis Lagrange, who noted their existence in 1772. If the small body is located at L4 or L5, the three bodies form an equilateral triangle in space. Viewed from either of the two larger bodies, the small body appears 60° ahead, or 60° behind, the other large body. In the Sun-Jupiter system, the L4 and L5 points mark the mean (average) positions of the group of minor planets (asteroids) known as the Trojan Group. The 3 remaining Lagrangian points in the Sun-Jupiter system do not allow stable orbits due to perturbations from other planets. In the Earth-Moon system, the L4 and L5 points (60° ahead and behind the Moon in its orbit) may already contain dust or gas clouds; these points have been considered as possible sites for space platforms.

See also:
♦ Lagrange, Joseph Louis Comte de ♦ Perturbation


Astro*Index Copyright © 1997 Michael Erlewine