Planetary Movement

Revolution is the movement of circling another object.

Rotation is the axion of an object spinning on an axis.

Gravity is the effect of mass from one object to another. It can affect any object smaller than itself. It's effect is to pull. That's simply it. To pull inwards. Orbit is usually caused from this and inertia of the object orbiting. Like most scientists usually describe this as "constantly falling" but because of gravity, your being pulled back at the same time your falling so you really ARE constantly falling.

Q: What are 2 characteristics that keep a planet in orbit?
A: One of two is gravity. Gravity keeps planets from being flung off into the cold abyss of space. Two of two is inertia. Without inertia you would get pulled into the object your orbiting.

Q: What are two factors that determine gravity between two objects?
A: The answer is simple and easy to remember. What is it? Well, it's mass and distance.