What are Lagrange points?
Q: What are Lagrange points?
A: Lagrange points are stable positions near large bodies in orbit. When two large bodies are in orbit around each other, there are places that a third body can occupy where the gravitational forces of the two large bodies and forces due to motion all balance up, allowing for a small object to keep more or less in a stable position.
Q: Who discovered Lagrange points?
A: The effect was named after the mathematician Joseph-Louis Lagrange, who wrote a paper on this in 1772 (long before we put satellites into orbit).
Q: How many Lagrange points exist?
A: There are five places called L1, L2, L3, L4 and L5.
Q: Are all of the Lagrange points considered stable?
A: The first three (L1, L2, L3) are called metastable because if a satellite gets a bit out of place, it will fall away from that point and not come back without using fuel. Meanwhile, L4 and L5 are considered stable - if a satellite gets a bit out of place it will be pulled back into place by the gravity and centripetal forces.
Q: What type of orbits do satellites use at these locations?
A: At those points satellites can use halo orbits to watch the sun looking for solar flares or they can be used for space telescopes such as the James Webb Space Telescope launched on 25 December 2021 which is located at an approximate million miles (about 1.5 million kilometers) from Earth.
Q: What objects inhabit these locations naturally?
A: Because L4 and L5 are stable they have attracted dust clouds as well as asteroids known as Trojan asteroids which inhabit larger planets more frequently than smaller ones like Earth-Sun system which has only attracted few asteroids.
