The force of gravity between two objects is determined by the mass of each object and the distance between their centers. Objects with a greater amount of mass will exert a greater degree of gravitational pull, but as the distance between two objects increases, the gravitational force between them lessens. The significance of distance with regard to large masses, such as planets, plays an important role in the science of Astronomy.
The relationship between mass, distance and gravitational attraction was first described in print by Isaac Newton in his "Principia." Newton's Law of Universal Mutual Gravitation is an inverse-square law that states that the force of gravity between two objects is an inverse proportionality in relationship to the distance between them.
An example of the significance of distance in Newton's law is how a person's weight decreases when they are further away from the center of the Earth, such as in an orbiting space station. The gravitational force, experienced as weight, is decreased, even through the person's mass and that of the Earth remain the same.