What is gravity?

Jump as high as you can — and you always come back down. Something invisible keeps tugging you back to the ground. That something is called gravity.

Gravity pulls things together

Gravity is an invisible pull. Everything that is made of stuff — you, a ball, a mountain, a whole planet — pulls on everything else. The bigger something is, the stronger its pull. Earth is enormous, so its pull is strong enough to hold you, the trees, the oceans and the air gently down on the ground.

Why we don’t float away

When you drop a spoon, gravity pulls it straight down to the floor. When you jump, gravity brings you back. It is working all the time, even though you can’t see it. Without gravity, you would drift off into the air like a balloon — and so would everything else!

Gravity reaches into space

Gravity isn’t only here on Earth. The Sun’s huge gravity holds all the planets, keeping Earth looping around it year after year. Earth’s gravity holds onto the Moon, so the Moon stays close to us instead of wandering off. Gravity is the invisible glue of the whole sky.

Wonder fact: The Moon is much smaller than Earth, so its gravity is weaker. On the Moon you could jump about six times higher than you can here — the astronauts who visited bounced around like kangaroos!