We have all seen footage of astronauts floating freely in space, performing twists and turns that seem to defy gravity. As a result of these portrayals, many people believe that there is zero gravity in space. However, this statement could not be further from the truth. Gravity exists everywhere in the universe and is the most important force affecting all matter in space. In fact, without gravity, all matter would fly apart and everything would cease to exist.

Gravity is the attractive force between two objects at a fixed distance r. The strength of gravity is proportional to the mass of the two objects and inversely related the distance between them. A larger massed object has a greater gravitational force than a smaller massed object does which explains the difference between the gravitational field of the Earth and Moon. The force of gravity between two objects decreases rapidly at a rate of 1/r2. Thus, the gravitational force of two equal masses 1 meter apart is 100 times stronger than if the masses were 10 meters apart. Using the two parameters, mass and distance, we can understand how gravity operates in the universe and causes objects to appear as though they are experiencing zero gravity in space.