What is a Lagrange point?
Quick Answer
A Lagrange point is a spot in space where the gravity of two large bodies, like the Sun and Earth, balances a spacecraft's orbital motion so it can stay in position with little fuel.
The Full Story
Every two-body system such as the Sun and Earth has five Lagrange points, labelled L1 to L5. Leonhard Euler found the first three, and Joseph-Louis Lagrange identified L4 and L5 in 1772. Spacecraft placed near these points keep a fixed position relative to the two bodies. The James Webb Space Telescope orbits the Sun–Earth L2 point, about 1.5 million km from Earth on the side away from the Sun. L4 and L5 are stable, which is why groups of Trojan asteroids gather at Jupiter's L4 and L5 points.
Key Facts
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Suggested video title for this topic:
"Parking spots in space — how Webb stays put 1.5 million km away."