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Would it theoretically be possible for a planet to stay at the same place in an "orbit" of its parent body? (lemmy.blahaj.zone)
submitted 1 week ago by birdwing@lemmy.blahaj.zone to c/askscience@lemmy.world
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See title. This is a shower thought that popped into me while slowly waking up. I'm thinking, what if due to e.g. gravitational shenanigans, the pull on a planet is such that a planet stands relatively motionless in a fixed position towards its star?

Is that possible or am I forgetting some astronomy basics?

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[-] ZeroGravitas@lemmy.dbzer0.com 2 points 1 week ago* (last edited 1 week ago)

You mean a tide locked planet, as in, one side of the planet would always face the star? The Moon does this with respect to the Earth, so yes, it is possible.

If you mean no spinning around the star, then no. The orbital equilibrium is given by the attraction force between the planet and the star being countered by the centrifugal force of the planet spinning around the sun. If the planet were to slow down, it would move closer to the star. If it would stop, it would eventually fall into the star.

[-] phdepressed@sh.itjust.works 1 points 1 week ago

What if something was just plopped gravitationally equidistant from two stars in a binary system?

[-] frongt@lemmy.zip 1 points 1 week ago* (last edited 1 week ago)

If it was perfectly balanced, sure. Any slight imbalance would cause rapid destabilization.

Also the pure gravitational forces might just rip that thing apart.

[-] FlexibleToast@lemmy.world 2 points 1 week ago

I think the closest thing to what you're talking about is a Lagrange Point

[-] birdwing@lemmy.blahaj.zone 0 points 1 week ago

Yeah, this seems to be the closest. Or as another in the thread answered, inbetween two parent bodies. Would probably not be stable for that long, though...

[-] threelonmusketeers@sh.itjust.works 2 points 1 week ago

Lagrange points L4 and L5 are stable (think trojan asteroids), L1, L2 and L3 are unstable and require some propellant for station keeping (think James Webb).

[-] FlexibleToast@lemmy.world 1 points 1 week ago

Yeah, that doesn't really work. https://en.wikipedia.org/wiki/Three-body_problem

[-] Ludicrous0251@piefed.zip 1 points 1 week ago

Ah yes, the hyperintelligent aliens send sentient subatomic particles to fuck everything up, don't they...

[-] MalReynolds@slrpnk.net 0 points 1 week ago

If you stuck the 'planet' at the center of mass of two (or more) orbiting stars, I guess ?

It wouldn't be a stable system, but you could use active stabilization (i.e. honking big rockets) if you had your heart set on it.

[-] threelonmusketeers@sh.itjust.works 1 points 1 week ago* (last edited 1 week ago)

Assuming you could determine your position between the two stars with decent accuracy, you shouldn't need a "honking big rocket" just to maintain your position. A small ion engine or cold gas thruster should suffice.

[-] MalReynolds@slrpnk.net 1 points 1 week ago

Depends how big a planet is...

this post was submitted on 03 Feb 2026
3 points (80.0% liked)

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