What we know about gravity and the motion of objects came from Sir Isaac Newton. In 1687, he published his laws of gravity and motion in his book Principia.
Newton’s law of gravity states that every particle of matter in the universe attracts every other particle of matter in the universe. The power of a particle’s gravity depends on its mass and the distance between it and the particle it is attracting.
Newton’s first law of motion says that any object at rest or moving in a uniformly straight motion will stay that way until another object or force acts upon it. (Body A stays at rest until Body B disturbs it.)
The second law states that when acted upon, the object at rest will respond by moving in the same direction and with the same momentum as the force or other object (providing that no other force is at work). (When moved by Body B, Body A moves with the same momentum and in the same direction as Body B.)
Law number three describes how the object set in motion by a force will exert an equal force in the opposite direction against the force that moves it. (When Body B exerts a force on Body A, Body A in turn exerts an equal force on Body B, in the opposite direction.)