The Universe (for thinking people only)

Originally posted by FabianFnas
Now the Moon loses its orbital energy due to mutual tide forces. When Earth and Moon mutually are in geo-synchronous rotation, the Moon will gradually sink back in orbit and eventually fall on Earth.

I haven't been able to find confirmation for that - any references?

Originally posted by avalanchethecat
I haven't been able to find confirmation for that - any references?

It is physics. Tidal forces between the Earth and the moon are in a constant "tug of war". As the Earth slows down, its angular momentum gets transferred to the moon, causing it to have more energy and it moves to a higher orbit.

Once the rotational period of the Earth (the day) matches the orbital period of the moon (the month), then the moon will stop moving further out and wouldn't have enough speed and its centripetal force to be less than the gravitational pull between them at that distance, and they will be pulled back together.

EDIT: However, the sun would have become a red giant and have completely engulfed the Earth and moon by then.

Thinking about it, the Earth-moon system will certainly become geosynchronous, but is the conclusion correct that by that time there would be not be enough energy in the moon's orbit for them to come together?

It all depends how far apart and how fast they are going at the time that they become geosynchronous. Anyone done any calculations on this?

I have found this reference on a science forum describing friction of the solar tides causing the moon to lose energy and then come back to earth.

http://www.bautforum.com/showthread.php/34229-The-Moon-leaving-Earth-s-orbit

Originally posted by lausey
Thinking about it, the Earth-moon system will certainly become geosynchronous, but is the conclusion correct that by that time there would be not be enough energy in the moon's orbit for them to come together?

It all depends how far apart and how fast they are going at the time that they become geosynchronous. Anyone done any calculations on this?

It seems there are some serious misconceptions about gravity and orbits going on in this thread.

1. Everything else being equal, the moon would continue to orbit the earth at a fixed distance forever. That is a basic law of conservation of momentum.
2. The moon is pulled away from the earth due to angular momentum and pulled towards the earth by gravity. These two forces are in balance and are stable ie if the moon gets closer to the earth the force pulling it away becomes significantly stronger, and if it gets further away the same force becomes significantly weaker. This variation is greater than the variation in gravity, thus the moon will always stick to its orbit.
3. Tidal forces result in geosynchronization. The moon has already been forced into synchronization causing it to always face the same side towards earth. The moon is going slower than earths rotation, so the tidal forces are causing the earth to slow down the earths rotation and speed up the moons orbit. The result is the moons orbit gets further away from the earth. Once they are synchronized, the moon will not magically fall to earth, it will continue to orbit at a given distance.

http://en.wikipedia.org/wiki/Orbit_of_the_Moon#Tidal_evolution
According to wikipedia, all things being equal we have another 50 Billion years to go, but since the oceans will have evaporated long before that, it might take much longer.

Originally posted by twhitehead
It seems there are some serious misconceptions about gravity and orbits going on in this thread.

1. Everything else being equal, the moon would continue to orbit the earth at a fixed distance forever. That is a basic law of conservation of momentum.
2. The moon is pulled away from the earth due to angular momentum and pulled towards the earth by gravi ...[text shortened]... rs to go, but since the oceans will have evaporated long before that, it might take much longer.

That is what I thought hence my following posts, but then realised (with confirmation from what someone else said in another forum) that solar tidal forces will cause the moon to lose more energy.

Originally posted by vishvahetu
You have completely missed the point....the point is that, isnt it astounding that we have this mysterious force that scientists call gravity.

Gravity is a enregy/force created by God to allow the functionallity of universe as we observe it.

But the cheating scientists say its just there, whithout cause or design, and this is their nonsense.

😴

Originally posted by lausey
That is what I thought hence my following posts, but then realised (with confirmation from what someone else said in another forum) that solar tidal forces will cause the moon to lose more energy.

That is wrong. The moon is gaining energy from the earths rotation ie it is slowly starting to go faster in a larger orbit while the earth is slowing down. Interestingly (and I hadn't realized this till I looked it up) the actual period of the moons orbit slows down because it has a larger orbit.

The sun is also slowing down the earth, but not quite as much as the moon is.

Its also interesting to note that the change in the moons orbit was noticed way back in 1695.

http://en.wikipedia.org/wiki/Tidal_acceleration

There are apparently other factors too.

Originally posted by twhitehead
It seems there are some serious misconceptions about gravity and orbits going on in this thread.

1. Everything else being equal, the moon would continue to orbit the earth at a fixed distance forever. That is a basic law of conservation of momentum.
2. The moon is pulled away from the earth due to angular momentum and pulled towards the earth by gravi ...[text shortened]... rs to go, but since the oceans will have evaporated long before that, it might take much longer.

You miss the entire point, the statement that the moon could crash into the earth is mentioned to have you see that something remarkable is going on, and its a tongue in cheek comment.

What is going on is beyond the scientists understanding, so they give all these forces names, and just marvel at their existence, but give no credit to the force maker.

You talk of balance and sycronocity and forces and gravity, but these are the workings of an intelligent design.

Originally posted by twhitehead
That is wrong. The moon is gaining energy from the earths rotation ie it is slowly starting to go faster in a larger orbit while the earth is slowing down. Interestingly (and I hadn't realized this till I looked it up) the actual period of the moons orbit slows down because it has a larger orbit.

The sun is also slowing down the earth, but not quite a ...[text shortened]... .

http://en.wikipedia.org/wiki/Tidal_acceleration

There are apparently other factors too.

Yes, aware of why the moon will go further out, but once it becomes geosynchronous, the solar tidal forces will become dominant. It also makes sense that the moon's orbital period will be longer, because the gravitational pull between the earth and the moon will be weaker further out and hence the centripetal force will have to be less to equalise.