What Is Gravity, and Why Doesn't It Fling Us Off the Earth?

The Earth is spinning at over 1,000 miles per hour right now. Here's why you're not flying off into space.

Right now, you're standing on a giant ball spinning at over 1,000 miles per hour and hurtling around the sun at about 67,000 miles per hour. So why aren't you flying off into space? The answer is a force so constant you barely notice it: gravity.

A pulling force, everywhere

Gravity is a force that pulls any two objects with mass toward each other. Every single object with mass has some gravity — you have gravity, this article has gravity, a pencil has gravity — but the effect is only noticeable when at least one of the objects is enormous, like a planet.

Earth is massive enough that its gravity pulls everything near it — including you, the air, and the ocean — firmly toward its center. That's why things fall down instead of drifting sideways, and why you stay firmly on the ground instead of floating away.

Why the spin doesn't win

Earth's spin does create a tiny outward push, technically making you weigh a very slightly smaller amount at the equator than at the poles. But Earth's gravity is enormously stronger than that small spinning effect — strong enough to hold down oceans, mountains, and an entire atmosphere without any trouble. The spin is real, but gravity simply wins by a huge margin.

Mass is the key ingredient

The bigger an object's mass, the stronger its gravitational pull. That's why the Moon, which has much less mass than Earth, has weaker gravity — about one-sixth of Earth's. An astronaut who weighs 150 pounds on Earth would weigh only about 25 pounds on the Moon, even though their actual mass — how much "stuff" they're made of — hasn't changed at all.

Gravity also explains why planets orbit the sun instead of flying off in a straight line: the sun's enormous mass constantly pulls each planet toward it, bending their path into a loop instead of letting them travel in a straight line forever.

A question to think about

If you visited a planet with much stronger gravity than Earth's, what do you think would feel different about everyday activities like walking, jumping, or picking things up?