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GrizzKarizz t1_j4ytefp wrote

Reply to comment by CremePuffBandit in Are Two Tidally Locked Earth in One Solar System Possible? by Thirdy-DOg

Similar question, if there was another Earth sized planet in our (therefore each other's) langrange point, would that be stable?

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slinkymcman t1_j4yyfsf wrote

No Lagrange points only work because the mass is negligible at them

Edit Lagrange are stable because they don’t impact forces on the other two bodies when you account for rounding errors

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MrMe_1621 t1_j4yzbto wrote

No, the planets would probably end up orbiting each other or colliding. Lagrange points are stable for things like satellites because their masses are insignificant compared to the Sun and Earth. If an Earth-sized planet was at one of the Lagrange points(mostly L1 and L2, I’m not sure about L3-5), the planets would be attracted to each other much more than to the sun.

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sault18 t1_j4zoyr1 wrote

Isn't Theia hypothesized to either have formed or migrated into Earth-Sun L4 or L5 point and then had to be gravitationally nudged out of there by Jupiter and / or Venus?

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pmMeAllofIt t1_j527nft wrote

L4/5 isn't stable for larger object. If Theia collected enough mass it would nudge itself out without the help of other bodies of mass. Being about 10% Earth's mass in the Sun-Earth L4/5 points I believe.

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GrizzKarizz t1_j53hikz wrote

I meant the L3 point, but I assume you are right and that it's not possible.

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MrMe_1621 t1_j53prs2 wrote

Well, of all the points I think L3 would be stable the longest since the attraction between planets is minimized. Over time the extra force might cause them to spiral inwards, but the effects of other planets would destabilize things more quickly.

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