Jeffrey Andrews-Hanna

Gravity is what holds us down to the Earth, despite some people who claim it doesn't exist.

Without gravity, we'd all go flinging off into space.

So we're very happy that we have gravity on the Earth.

Gravitational acceleration on the Earth's surface is about 9.8 meters per second squared, about 30 feet per second squared.

The moon also has gravity, not surprisingly.

Gravity on the surface of the moon is about 1 fifth of gravity on the surface of the Earth.

Now we know this in part because we sent astronauts there and they walked around, they didn't fly off.

That one fifth gravity means they did kind of a funny little, I don't know, galloping bunny hop across the surface of the moon, but it was enough to let them walk.

But we can actually, we don't have to send people to the moon to know it's got a gravity field because we can feel it here on the earth.

People have been observing the lunar gravity field for millennia.

All you have to do is go to the beach.

The tide comes in, the tide comes out.

You're seeing the effects of the moon's gravity field on the Earth.

So that's another way we can measure it.

But the earth and the moon aren't the only objects out there with gravity.

In fact, anything that has mass has gravity.

Now we all know people who think they're the center of the universe.

I know that I'm not the center of the universe, but I am so important, I have my own personal gravity field.

So I exert a pull on everything around me,

It's a teeny, tiny pole, but it's a pole.