Why doesn't the moon fall down?

Question

I have a project and want to know why?

Answer 1

Centrifical Force. Since the moon is traveling so fast and at a constant rate, it isnt enough speed to leave orbit or small enough speed to crash to earth.
Gravity is always pulling on the moon and since it is moving so fast it stays in orbit

Answer 2

Why doesn't the moon fall down?

well its perty simple realy
Ok the moon is a great big enormous lump of rock, and it is up in the sky, why doesn't it fall down?


Now there was a very clever man about 400 years ago called Sir Isaac Newton, who, in between discovering lots of mathmatics, writing about theology and inventing the wibbley edges on pound coins, was thinking about this sort of problem.




The first question he asked was what do we mean by fall down? If falling down means that everything falls in the same direction, and the world is round, things on the bottom of the Earth wouldn't stay there very long..


So obviously falling down means something a bit different! What happens is that everything falls towards the centre of the earth, (that way the kangaroos don't have to be tied down!). Now Issac started thinking about a cannons, now he knew that the faster you fired the cannon ball the further it went.


Now Issac, possibly sitting in a pub, thought what would happen if we had a really big cannon - no a really, really, really, reeeeaaally big cannon, and put it on top of a mountain (Oh and pretended there was no air to slow it down), how far could you get it to go?


So if you make the cannonball go fast enough it keeps falling all the time, but it never falls quite fast enough to actually hit the ground. This is called an orbit, and how astronauts, satellites, the moon don't crash into the earth.

So the moon, it is actually falling down all the time, just it allways misses the earth and allways will.

Answer 3

Newton's first law of motion states that an object a rest will remain at rest and an obect in motion will continue to move in a straight line at a constant speed unless acted on by a force. This is the law of inertia.

The moon, like every moving object, has inertia. Left to itself, it would move in a straight line at a constant speed. But it's not left to itself. The Earth exerts a gravitational force on it, and it exerts a gravitational force on the Earth. The force is proportional to the masses of the Earth and the moon. The two bodies have settled into a state where their mutual attraction balances their inertia.

The result is that the moon orbits the Earth. Technically it is always falling towards the Earth, but its trajectory takes it completely around the Earth so there is never a collision.

Even more technically, both the Earth and the moon orbit their common center of mass. However, because the Earth is much more massive than the moon, the center of mass is actually inside the Earth (although not at its center), so for all intents and purpose we can say that the moon orbits the Earth.

Answer 4

Actually, the moon wasn't thrown extra hard--it is moving further from the earth because the earth is spinning faster than the Moon orbits the earth--it's all to do with tides....

The earth pulls on the moon, and the moon pulls on the earth. This makes both bulge slighlty, or creates tides.

The moon always presents the same face to the earth because since it is so small, tidal friction with the earth added energy to the moon, making it orbit in exactly the same amount of time that it rotates. The earth experiences this friction too, though it is much bigger than the moon so the effect takes longer. Since the moon is "slowing" the rotation of the earth, that energy has to go somewhere--it goes to speeding the moon up, which makes the moon move further from the earth.

This concept is called the law of conservation of angular momentum. It is the same thing that ice skaters use when they start spinning--you'll notice that they can control how fast they spin based on whether they pull all their limbs tight to their body (fast) or spread them out (slow).

Answer 5

Alex b had the best answer so far. He explained it perfectly. The moon IS falling down, but it's moving sideways so fast that it keeps missing the Earth.

I just wanted to add that when the moon was formed, it was "thrown" just a little harder than necessary to keep it in orbit. It is actually gradually moving farther and farther from the Earth. Eventually, billions of years from now, it will fly off into space never to return....if the sun doesn't destroy both the earth and the moon first.

Answer 6

The moon orbits the Earth due to the gravitational pull the Earth has on the Moon. In the same way that the Earth orbits the Sun because of the Sun's gravitational pull.

Answer 7

Actually it is falling down! If it wouldn't be, it would fly away into space.

Imagine yourself throwing a ball. It will follow a curved trajectory. The faster you throw it, the further it flies. Throw faster and faster, eventually you've reached a speed (if you're superman) where the ball will follow the same curve as the surface of the earth. The ball will never touch down again, it will continue to fall but because it is also moving forward, the distance to earth stays the same.

This is what the moon is doing. It falls down to earth just fast enough to keep it from flying away into space, without actually falling hard enough to decrease the distance and eventually crash.

Answer 8

Its orbital velocity is high enough that, even though it is always falling toward the earth, it doesn't get closer. It's the same principle as the International Space Station and any other object that is in orbit around the earth. Swing a yo-yo around your head and feel the tension on the string.

Answer 9

its the same reason why earth isn't attracted to the sun

the gravitational energy exerted by the earth on the moon is cancelled by the centripetal force of the earth

Answer 10

It is but the earth is falling at the same speed