Planet orbits around the sun

Gravity keeps the planets a certain distance from the sun; but what causes them to orbit? Where does their momentum come from? How are they moving through the orbit?

When the planets were first formed by collisions of many of Asteroids, The speed was set.

Gravity and centrifugal force keep them in orbit.

Gravity causes them to orbit.
Centrifugal Force keeps them from falling into the sun.

Speed was caused when stars supernova'ed and created the material asteroids are made of.

The planets are coasting forever in the frictionless vacuum of outer space on the momentum they got from their original formation long ago. That momentum came from the sum total of small random motions of all the particles in the ancient nebula which collapsed to form the Sun and solar system. It is similar to the way all random motions in a tub of water create a little whirlpool as they are all collected near the drain as you drain the tub.

Anything moving has momentum.... without any other force acting on a body, it will continue to move in a straight line.

The sun's gravity is the force acting on the planets, causing their paths to curve into an orbit. It's very much like going outside & throwing a rock - it's path is curved due to gravity. And, it *hits* the ground because you can't throw it fast enough to achieve an orbit... That's essentially what all the planets are doing - they're *falling* toward the sun, but they're moving so fast sideways, they keep *missing* it...

sun has a huge amount of gravity, so you know you a day is how much it takes to orbit once, a year is how much it takes to orbit the sun

Still has momentum from formation.