What enables the moon to continue to orbit around the earth?

Question

A satellite will only orbit the earth for a few years before it will be forced out of orbit but the moon has been orbiting for 15 billion years, so what prevents the earths gravity from pulling it in? What keeps it going and why doesnt the friction caused by the earths gravity(the force that prevents it from flying away) slow it down?

Answer 1

It's the calming affect of cheese.

Answer 2

It has to do with angular momentum and the distortion of space-time. The moon's orbit around the Earth will not be stable forever. Not only is the Earth's gravity acting upon it but every other celestial body in it's vicinity including the sun and other planets. The moon has enough momentum to keep it spinning around the earth for a very long time, like a marble in a funnel. How this occurred can be explained in many ways, for example, the moon may have been a part of a larger body(s) that passed near and/or collided with the earth. The earth is potmarked with ancient impacts. One of these chunks may have had the right velocity and approach to enter a "stable" orbit around earth. Depending on gravimetric forces, like the marble, the moon may one day fall into the earth or possibly fly away from it entirely due to falling into the gravity well of another celestial body.

It's also worth noting that for some planets, the moon was formed when the gases and matter chunked up during the early stages of a planet's development. The existing motion of this cloud of dust could easily place the moon into orbit around the central planet. Similar to the way the solar system and planets evolved.

Answer 3

A lot of people gave you partially correct (even incorrect) answers. Here is the correct answer.

1) Satellites orbit the earth a lot longer than a few years, and they don't get "forced" out of orbit unless acted on by an outside force. However, their orbits do decay by design, which causes them to fall to earth and burn up in our atmosphere.
2) The earth is only 4-1/2 billion years old, hence the moon couldn't have been orbiting it for 15 billion years.
3) The moon experiences the Earth's gravity the same as anything else near it, but it also experiences centripetal force.

Lets imagine we wanted to launch an object into an orbit just like the moon, say a canonball.

Take a large and powerful cannon. The more gunpowder we pack behind the cannon ball the further it will travel. Now imagine setting up our super powerful cannon and firing it so that the cannon ball lands say 1,000 miles away. Now pack in more gunpowder and fire again, this time it will have traveled further, say 2,000 miles, before falling to the ground. Keep repeating the exercise and adding more gunpowder every time, and every time the cannon ball is fired it will travel further before it falls to the ground. Eventually, with enough power behind it, it will go all the way around the world before falling to the ground, and will have almost reached its starting point - it will land just behind you. Now, by packing in even more gun-powder, and getting just the right trajectory, it will over-shoot you and keep on going, it will not land. What the cannon ball is now doing is permanently arcing back down towards the Earth, but the curve of the Earth is falling away at the same rate, the cannon ball never 'catches up' with it. This is known as being in "free fall', the cannon ball is in orbit.

Astronauts aboard the International Space Station are in free fall, just like the cannon ball. The ISS - and the astronauts - are prevented from being thrown out of orbit (like the water that gets thrown out of the clothes in the spin drier) by the force of gravity. This balancing force is called centripetal force, and keeps the ISS in a closed orbit. Because the centrifugal force is exactly balanced by the centripetal force of gravity the astronauts aboard the ISS will not feel any sensation of centrifugal force. This is another example of the equivalence principle, which says that the effects of gravity and acceleration are indistinguishable from one another, and in this particular case they exactly cancel each other out.

In actuality, the moon's orbit is increasing a small amount each year. Someday, millions of years from now, we may actually lose it!

Answer 4

The invisible frame work large masses such as the moon ,planets and galaxies “hang” on to is called a gravitational field. These fields influence objects within these regions . The influence they create are detectable as gravitational forces, ie; "pulling forces" .These forces change the momentum of an object.The movement of the known moons, planets and galaxies are governed by the resulting balance form the laws of momentum and the laws of gravity. One pushes away and the other pulls in respectably. Newton was able to show that the force that say, causes an apple to fall to the ground, is exactly the force which influences the moon to orbit the earth. Einstein’s general theory of relativity explained this phenomena in terms of a local space time perturbation caused by mass, itself yielding an even more precise calculation of this gravitational force. How something here affects something there without any detectable rod or scaffolding is answered by the yet to be discovered graviton, mediator of the gravitational force, something akin to photons, the quanta which mediates the electromagnetic forces. This graviton is something like a billardball which goes from here to there “interacting” an exchanging this force. Having provided all this background info allow me now to divulge the answer;
Because there is nothing opposing it's movement!

Answer 5

Actually, the moon is falling towards the earth. There is no friction because friction requires two items to touch. When a object is in orbit around another object, it is actually moving perpindicular at the exact same rate that it is being pulled toward the object it is orbiting. The moon is getting closer, but only on the order of milimeters per year.

Answer 6

Because of the orbit its in. Its slowly moving outwards. Friction is only caused by two objects in contact. Gravity is pulling it towards earth but it falling away. Also satellites are in degrading orbits that are designed to bring them lower into the atmosphere thus burning them up.

Answer 7

"...moon has been orbiting for 15 billion years..."
Sorry, but this isn't correct. The solar system, including the Earth and moon, have existed for no more than 4.5-billion years.

The moon has a velocity vector AWAY from Earth that counters the force of gravity trying to pull it down. Also, the moon is receding from Earth at about 1.5 inches/year so Earth's tug on it is gradually weakening.

Answer 8

the moon has sufficient velocity to make it orbit the earth forever but the moon is actually slowly pulling away from the earth, it will eventually break free of the earths gravity and go spinning out into space. there was a time when it was much closer to the earth.

Answer 9

It is the velocity of the moon and the gravitational force between them keeps moon in orbit. Satellites orbit at a very lower altitude and they do have a negligible air resistance that bring them down. But the moon is very far away and absolutely no atmospheric drag. So the velocity remains the same

Answer 10

Inertia pushing the moon into space + earth's gravity pulling it back = orbit

Answer 11

The moon is much larger and denser than a man made satellite! Its mass and orbital velocity keeps it there. It is still falling toward earth.