For example, the force doubles in size if either of the masses is increased to twice its mass. On the other hand, the force grows weaker if the two objects are moved farther apart. In fact, it is inversely proportional to the square of the distance between them, so that if the distance is tripled, the force is only one ninth as strong. The gravitational force of the sun, acting on the earth, keeps the earth in its orbit, preventing it from traveling away into interstellar space. The gravitational force of the earth, acting on us, holds us to the earth's surface.
Every planet has mass and so every planet exerts a gravitational force on nearby objects.
We say that planets have gravity. However, what we really mean is that there is a gravitational force of attraction between the planet and a person standing on the planet's surface. This force depends on the visitor's mass, the planet's mass, and the planet's radius. Accordingly, people have different weights on different planets. 25 lbs on the moon.