this post was submitted on 02 Nov 2023
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Asklemmy
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I learned recently how the James Webb Space Telescope is not orbiting around Earth but literally orbiting around an empty point in space. I donβt think I even quite understand it, but itβs really cool
For everyone who immediately thinks 'it's most likely orbiting a point within the earth,' here's a diagram to help:
Have no idea how this works... there is no gravitational pull at the L2 point, it's just an empty point in space π€¨.
There is gravitational pull, from both the Earth and the Sun. The JWST is orbiting the "earth-sun system" if you will.
You can read more about Lagrange points here.
So they solved the Three Body Problem?
It's not really a three body problem. For that, the gravity of the JWST would have to affect the other two bodies, but its gravity is negligible.
JWST isn't going in circles, it's orbiting the sun. If you look at it relative to that, then it looks more like a sine wave rather than going in circles. However from the perspective of the earth, it looks like it's going in circles
You're tell me bro. I need to research this more.
Maybe gravitational push-pull between planets and moons... IDK, it might be some sweet spot they discovered where gravitational forces do weird things, lol π.
This. There's 5 Legrange Points for every 2 body system. They're specific points around the 2 bodys where the gravity "cancels out". In this case the 2 body system is the Earth and the Sun. JWST is sitting a million miles from Earth at L2.
Dammit, I was feeling proud that my first thought on how this could work lined up with the explanation... But I had assumed L2 (didn't stop to think about the label) was where I now see L1 to be. I can wrap my head around L1 just fine, but how the heck is L2 the same? Or the others for that matter? Gonna stare at this for a while...
If you understand gravity wells, think of L1/L2/L3 as the shape of a saddle. If you're right in the middle of the saddle it's a pretty stable orbit, but if you get too close to any of the edges you fall right out of it. L4 and L5 are like the peaks of a mountain.
Also worth pointing out that only L4 and L5 are stable, L1/L2/L3 are only metastable where they require a bit of maintenance to stay there.
Another fun fact about Legrange Points: There's a group of asteroids called the Trojan Asteroids. There's technically two groups of these since they're stuck in L4 and L5 in the Sun/Jupiter system.
Ah, so that's why we don't put shit in L4 and 5 π... things will bump in them once in a while π.
Yeah but it's not at the L2 point, it's spinning in a circle around L2.
Yes, my point exactly. There is no mass at the L2 point, so how can it spin around it.
Others explained it though, it makes sense now π.
PS: What are enbies �
I think they did that on purpose