4 ms·
If the moon wasn't drifting away and was in a static orbit, would the Earth's rotation slow and the moon's orbit speed up to the point where they're in sync?
by redact207 4y ago
If the moon wasn't drifting away and was in a static orbit, would the Earth's rotation slow and the moon's orbit speed up to the point where they're in sync?
- yellowapple 4y agoEventually, yeah; just as the Moon is tidally locked to Earth, Earth would be tidally locked to the Moon. I don't know offhand whether that would happen before the Moon drifts too far away to remain in Earth's orbit, however.
- sliken 4y agoMoon is below escape velocity, so it's not leaving. In fact when 1 day = 1 lunar month the movement away will stop, and reverse. It will continue to get closer to earth until it hits the Roche limit and becomes a ring.
- aussieshibe 4y agoFair warning: everything I know about orbital mechanics is from Kerbal Space Program. The moon cannot orbit at a higher speed while keeping the same semi-major axis (average distance to the orbital centre of mass). If you suddenly doubled the orbital speed of the moon right now, the apoapsis (the highest point in its orbit relative to the orbital centre of mass) would increase significantly. If you slowly accelerate the moon in the direction of its orbital velocity consistently over a long time period, the moon will slow down relative to the Earth, but it's semi major axis will increase. Actual scientists of HN: have at me.
- incompatible 4y agoYeah, the moon isn't "drifting away" on its own, its being forced away as it takes energy from the Earth.
- robertlagrant 4y ago> Fair warning: everything I know about orbital mechanics is from Kerbal Space Program. Knowing what I know about that game I read this as: Warning; I actually know what I'm talking about here.
- cwillu 4y agoIt depends; there's actually a mod that adds realistic n-body gravity, and it's remarkable how much it affects.
- deleted 4y ago[deleted]
- devoutsalsa 4y agoThe moon is drifting away because the Earth is rotating. Eventually the Earth will be tidally locked with the moon, the same side of the Earth facing the moon at all times. When this happens, the moon will (for the most part) stop moving away from the Earth. Well, that’s what would happen if we didn’t get eaten by the sun when it morphs into a red giant. For further research, check out… “Will the Moon ever leave the Earth’s orbit?” => https://youtu.be/IM_euz9PUiw https://youtu.be/IM_euz9PUiw
- dotancohen 4y agoIt's already happened! More at the end. This is called tidal locking, and if the universe consisted of only the Earth and moon, this would in fact happen. However, the big heavy Sun also affects both the Earth and moon's rotations. So why do I say that it has happened? Because the moon, having significantly less mass than the Earth, is almost tidally locked to the Earth. That's why we always see the same side of the moon. So the Earth's rotation hasn't synchronized with the moon's revolution, but the moon's rotation has nearly synchronized with the Earth's revolution (actually both the Earth and moon revolve around their common barycenter).
- sliken 4y agoYes, but it will take a long time. Then very slowly the moon will slow down, decrease it's orbit, until it hits the Roche limit and becomes a ring.