Why Does Earth Keep Spinning Around the Sun?

[pivoxa15]

Apparently, Moon slowly drifts away from Earth on average.At least, I've heard/read so.Big Oceans effect?Apparently.

That is better news than if the moon was slowly drifting inwards. What was the reason for why the moon is drifting away?

 

[DaveC426913]

It is stealing energy from the Earth's rotation. The Moon is pulling on the imperfections in the Earth's sphere, slowing it down in the same way you stop a slowing fan with your hand.

In turn, the Moon is given the extra energy, which boosts it into a higher orbit. I believe this process will stop once the Earth has been slowed to a one-face like the Moon is now. Then the Moon will begin spiralling in again.

 

[Ki Man]

I have heard that in space there is not entirely vacuum, so after extremely long time, these atoms would stop the Earth enough to make it go swoop into the sun? Or would it's kinetical energy be empty someday so it would fall into the sun.

its possible, but the particles are so small that it would have very little effect, although the Earth does colelct quite a few tons of dust every day out of space. most of the stuff floating in space would just burn up into the atmosphere and come down as dust, and i don't think a few specs of dust will send us on a collision course with the sun any time soon

 

[DaveC426913]

its possible, but the particles are so small that it would have very little effect, although the Earth does colelct quite a few tons of dust every day out of space. most of the stuff floating in space would just burn up into the atmosphere and come down as dust, and i don't think a few specs of dust will send us on a collision course with the sun any time soon

Well, it's true that it won't cause us to go on a collision course with the sun, but it's NOT because it's burning up in the atmo. Whether it burns up or not, it still contributes the same mass - and causes the same amount of friction.

 

[pivoxa15]

It is stealing energy from the Earth's rotation. The Moon is pulling on the imperfections in the Earth's sphere, slowing it down in the same way you stop a slowing fan with your hand.

In turn, the Moon is given the extra energy, which boosts it into a higher orbit. I believe this process will stop once the Earth has been slowed to a one-face like the Moon is now. Then the Moon will begin spiralling in again.

What is a one-face?

Would analysing it using action-reaction be better? i.e moon exerts a force towards the Earth (in order to make it more spherical?), the Earth exerts an equal and opposite reaction on the moon, sending it outwards.

Otherwise, it's Earth mechanically transferring some energy to the moon? Resulting in eath slowing down somehow such as slowing its spinning rate (hence losing kinetic energy) and moon gaining kinetic energy.

 

[D H]

It is often easier to look at these kinds of problems using conservation laws. The Moon raises tides (water and rock) on the Earth. If the Earth were rotating at the same rate as the Earth-Moon orbital rate, the tidal bulge would line up with the Earth-Moon line. However, the Earth's rotation advances the tidal bulge so the bulge on the Moon side of the Earth leads the Moon. This leading bulge exerts a slightly greater gravitational force on the Moon than does the trailing bulge on the opposite of the Earth. The Moon receives a small prograde boost, increasing its angular momentum. Conservation of momentum dictates that the Earth lose angular momentum.

 

[pivoxa15]

It is often easier to look at these kinds of problems using conservation laws. The Moon raises tides (water and rock) on the Earth. If the Earth were rotating at the same rate as the Earth-Moon orbital rate, the tidal bulge would line up with the Earth-Moon line. However, the Earth's rotation advances the tidal bulge so the bulge on the Moon side of the Earth leads the Moon. This leading bulge exerts a slightly greater gravitational force on the Moon than does the trailing bulge on the opposite of the Earth. The Moon receives a small prograde boost, increasing its angular momentum. Conservation of momentum dictates that the Earth lose angular momentum.

But that dosen't explain why the moon is moving away from the earth? It only says the moon is spinning faster.

 

[D H]

But that dosen't explain why the moon is moving away from the earth? It only says the moon is spinning faster.

I guess I wasn't clear enough. I said

The Moon receives a small prograde boost, increasing its angular momentum.

This increase in angular momentum is the Moon's orbital orbital angular momentum, not its angular momentum due to rotation about its axis. That increase in orbital angular momentum means that the Moon is moving away from the Earth.

In fact, the Moon's angular momentum due to its rotation will decrease over time. The Earth exerts a similar torque on the Moon. If the Moon rotates at the same rate as the Moon's orbital rate, the Moon's tidal bulge lines up with the Moon-Earth line and is fixed on the lunar surface. If the rotation rate and orbital rate differ, the bulge will be out of alignment and it moves, just as the tides move on the Earth's surface. Friction forces act against this motion of the tidal bulge, slowing or speeding up the Moon's rotation until it is once again in synch with the Moon's orbital rate.

 

[zennocobra]

yups.. i am wondering the same problem... and why does not it stop? or when does our Earth stop going around the sun? and spinning itself? It sure take "gigaterabillion" of energy to make such move... where does those energy coming from?

 

[DaveC426913]

yups.. i am wondering the same problem... and why does not it stop? or when does our Earth stop going around the sun? and spinning itself? It sure take "gigaterabillion" of energy to make such move... where does those energy coming from?

Newton's First Law: an object that is already in motion will tend to stay in motion (it requires no energy to do so).

It got the initial kick from the Big Bang, which gave everything a lot of kinetic energy. All that has happened since them is that everything has been transferring its kinetic and potential energy which, under gravity's influence, has everything tend toward elliptical paths.