Submitted by Any_Palpitation_3110 t3_z7gd3c in space
PoppersOfCorn t1_iy79h20 wrote
Reply to comment by Radiant_Nothing_9940 in what would be different if we had two moons by Any_Palpitation_3110
So basically, from the gravitational interaction between earth and the moon. The moon creates a bulge on the earth surface(tides) but this bulge isn't directly underneath the moon, so it causes torque, and the difference slows the earths rotation and also results in the moon continually moving away from earth
Ripper209 t1_iy7dm16 wrote
How does general relativity explain this?
JapariParkRanger t1_iy7e26z wrote
There are no major relativistic effects needed to explain tidal forces.
Ripper209 t1_iy7ekfy wrote
Can you please elaborate?
JapariParkRanger t1_iy7f6e1 wrote
General Relativity has little to do with tidal forces.
Ripper209 t1_iy7g210 wrote
Ngl im kinda stupid, how does the moon affect the tides then
TwoUglyFeet t1_iy7lii5 wrote
Gravity. The moon pulls on the earth like two people holding a rope. This force is called tidal force and causes to water (and the earth) to move to side closest to the moon. These are what tides are.
Ripper209 t1_iy7m41w wrote
In terms of general relativity, is this "rope" nonexistent? Are they just moving along curved paths caused by the mass of the moon and earth?
TwoUglyFeet t1_iy7nlu4 wrote
The moon is in earth's gravity well. This bending is the reason we see the forces of the Earth and moon acting on each other.
Ripper209 t1_iy7srji wrote
Thank you very much this was really helpful
strange--alien t1_iy88lp4 wrote
If you imagine this scenario, having a tennis ball on a string and holding it above your head spinning it like a helicopter rotor. Generally speaking, the tennis hall represents a moon, rope is the gravitational tether between the two, and (with a bit of imagination) your hand are represents the earth. So, when spinning the tennis ball around, the mass of the tennis ball sets a limit on the speed of spinning. One rotation is an earth day. If you had a heavier ball like a basket ball (larger moon) the speed of rotation would be slower because the earth has to sling a heavier moon. Spinning a lighter ball like a ping pong ball (tiny moon) would be so easy that the tiny moon wouldn't have any affect on spinning speed basically. Smaller you get and the moon wouldn't be able to hold itself in the earth's gravity and would fling off in to space. To summarise, larger moon puts a brake on our earth's rotation, Smaller moon would ease pull back on our earth. Two moon's would be wack! Double the werewolves, double the astrology readings. Spooky
Ripper209 t1_iy9mz4n wrote
This is exactly what I'm looking for thanks!
strange--alien t1_iya1txe wrote
I could hear your unspoken question very clearly. Btw I messed up one piece. One tennis ball rotation is one moon orbit (27 days), not one day. Still same physical concept though.
Ripper209 t1_iya3fef wrote
It's totally cool I appreciate it
[deleted] t1_iy7jka7 wrote
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