french mathematician and astronomer Joseph Louis Lagrange indicated that three bodies can rest on apexes of an equilateral triangle which rotates in its plane. If an individual of the bodies is sufficiently huge compared to one other two, then your triangular configuration is obviously stable. These types of systems are now and again called Trojans. The key apex associated with triangle is called the best Lagrange point or L4; the trailing apex is the trailing Lagrange point or L5.
by Juanita RudolphReport definition
Astronomy Dictionary for "Lagrange Point"