what hold the moon up in the sky?

Answer 1

Well first of all when you drop something it falls straight to the ground right? You also know that the Earth is round right? Now what happens when you throw a ball away from you parallel to the ground? It moves through the air in the direction you threw it, but it also falls toward the ground. If you were to throw that ball hard enough (and there was no air resistance) then it could move forward at a speed that made it so that the roundness of the Earth matches the rate at which the ball falls. Keep thinking of this and now picture the Moon moving around the Earth. It is moving at such high speed, parallel to the surface of the Earth, that as it is falling toward the Earth the Earth's surface is curving away from it at the same speed as it's downward movement (towards the Earth).

Answer 2

Nothing "holds it in the sky". It is actually falling toward the earth. The reason it never hits the earth is it is also moving through space as a speed great enough that the acceleration of the moon toward the earth keeps it moving in a (roughly) circular motion around the earth, rather than falling into it. If the moon were moving faster, it would escape the earth's gravity and not be in orbit any more. If it were moving more slowly, it would get closer and closer to the earth until we collided with it. The same thing keeps the earth in orbit around the sun. In reality, the moon is moving slightly faster than necessary for it to remain at a constant distance from the earth, so each year it is slightly further away from the earth on average than the previous year.

Answer 3

It's a nice balance between gravity and centrifugal force. The moon is spinning around the earth and normally, unless it were tethered, it would fly off at a tangent. But the earth's gravity provides that tether and keeps it pulled into its orbit. If the moon's speed was greater, or the earth's gravity weaker, it would have long ago left its position, but as things have balanced out so nicely, we can enjoy the glow of that friendly orb in our night sky.

Answer 4

First let me clarify that there is no 'up' or 'down' in space.

The Moon experiences gravitational pull by the Earth. In the absence of such a pull and any other force, it would have been moving on a straight path with a constant speed. But the gravitational force of the Earth gives it nearly the circular ( more correctly elliptical ) path. In classical mechanics, this is explained saying that the gravitational pull of the Earth is balanced by the centrifugal force due to uniform circular motion. In fact, there is no force like centrifugal force. It is just a concept to simplify application of mechanics. The path of any heavenly body moving round another larger body is correctly interpreted by saying that its angular momentum is constant as no net torque acts on it. In fact, in such motions both bodies revolve around each other, but the path of the larger body being smaller in length, it is usually considered to be stationary. Both revolve in such a way that their positions are colinear with their center of mass.

Answer 5

As the moon rotates around the earth. it is thrown outwards by centrifugal force. This is balanced by the combined pulls of the earth's and moon's gravity. Rather like swinging a conker around your head on a string.