The Earth tries to pull everything down towards its center. This pull is called the force of gravity (the invisible force). When you lift things up you have to pull against gravity. If you drop a pencil, gravity pulls it to Earth. If you rest the pencil’s mid-point on your finger, gravity will pull down equally on both sides of the pencil and it will balance in the air.
Did you know that there is no gravity in space? This is why astronauts float around in their spaceships. Did you know that there is gravity on the Moon? The gravity on the Moon is much weaker than the gravity that we have here on Earth. This is why moon walking for astronauts is very difficult.
Gravity or gravitational forces happen when one object attracts another. When the molecules of one object pull on the molecules of another object, that is gravity. It's like the Earth pulling on you and keeping you on the ground. That pull is gravity at work.
Read more about Gravity in today’s Science Fun!