Eli5 – How do probes at Lagrange points not drift in their orbits?

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Context I was watching a video about the JWST and saw that it orbited the sun at the L2 point, but that got me wondering as to how it doesn’t slowly drift in its orbit, considering its at a higher (but presumably at a similar eccentricity to that of the earths) orbit. Are higher orbits not always slower?

Basically how does the JWST not fall behind the earth, for lack of better phrasing.

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Anonymous 0 Comments

Lets assume that the orbits I’m discussing are all more or less circular, and define a ‘slower’ orbit as one where it takes more time to complete an orbit. If you’re considering just a small object orbiting a big object then higher orbits will be slower.

However, if you have a small object orbiting a big object, and somehow make the big object even bigger then the small objects orbit will be faster than it was before the weight gain.

The way the ‘L2’ point works is that the Sun and Earth both pull on the object in the same direction, this is basically the equivalent to the ‘bigger object’ idea above. So if you compare an object orbiting at L2, and one that is just orbiting the Sun at the same distance, the L2 object is faster because it’s getting ‘extra’ pull from the earth. The L2 point being the spot where the ‘fastness’ from the extra pull exactly cancels out the ‘slowness’ of the object being farther from the sun than earth.

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