I can give some background here! The moon orbits the earth every 27.3 days, whereas the Earth rotates once every 24 hours. Because of this, the earth drags the tidal bulge in the direction of its rotation, slightly ahead of the moon instead of pointing straight at it.
This in turn pulls on the moon, increasing its orbital angular momentum relative to the earth ever so slightly. More angular momentum means a larger orbit, and the moon’s orbital distance increases by roughly 3.8 centimeters per year.
This also means that, while the moon gains orbital angular momentum, the earth loses rotational angular momentum, so while the moon gains distance from the earth, the earth actually slows down its rotation.
Theoretically, in the eventual equilibrium state the other commenter noted, the earth and moon are both tidally locked to each other, earth completing one rotation and the moon completing one orbit in exactly the same amount of time, roughly once every 47 years.
Obviously this assumes a closed system with no influence from the sun, so it wouldn’t look exactly like this, and as the other commenter said it would take such a ridiculously long time (almost triple the current age of the universe) the sun will have expanded and destroyed the earth and moon far before this theoretical equilibrium state would ever occur
Because the moon orbits in the direction that the earth rotates, the moon is being flung into a higher orbit - like you said.
However, if the moon ended up orbiting in the opposite direction to the rotation of the earth, the opposite effect would have taken place - the moon would have been slowed down by the gravitational effects of the tides, and its orbit would have decreased.
At some point the moon would have been close enough to cross the Roche limit and it would have been ripped apart. The earth would have had rings like Saturn and probably would have endured huge collisions from moon chunks.
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u/pattywagon95 9h ago
I can give some background here! The moon orbits the earth every 27.3 days, whereas the Earth rotates once every 24 hours. Because of this, the earth drags the tidal bulge in the direction of its rotation, slightly ahead of the moon instead of pointing straight at it.
This in turn pulls on the moon, increasing its orbital angular momentum relative to the earth ever so slightly. More angular momentum means a larger orbit, and the moon’s orbital distance increases by roughly 3.8 centimeters per year.
This also means that, while the moon gains orbital angular momentum, the earth loses rotational angular momentum, so while the moon gains distance from the earth, the earth actually slows down its rotation.
Theoretically, in the eventual equilibrium state the other commenter noted, the earth and moon are both tidally locked to each other, earth completing one rotation and the moon completing one orbit in exactly the same amount of time, roughly once every 47 years.
Obviously this assumes a closed system with no influence from the sun, so it wouldn’t look exactly like this, and as the other commenter said it would take such a ridiculously long time (almost triple the current age of the universe) the sun will have expanded and destroyed the earth and moon far before this theoretical equilibrium state would ever occur