Gravity is the force that pulls objects together. It has been known by scientists for a long time. The force of gravity is constant and it affects objects of different masses in different ways.

If you were on a spaceship and you wanted to go to another planet, you would need to change the direction of your spaceship to go in the right direction. The same is true for objects on Earth. The Earth is a planet in the solar system. The sun is the star that provides energy to Earth. It has a mass of about 1.4 solar masses and it emits about 4.6 million miles per year.