# Gravity Keeps Us Down to Earth

## What is Gravity?

Gravity holds us to the surface of the Earth and keeps our atmosphere wrapped around our planet. An object’s weight is a measure of the gravitational force acting on it.

## How Much Would You Weigh on Another World?

If you visited another world, you would notice a change in your weight, because the force of gravity acting on you there would be different from the force of gravity here on Earth.

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## Why Would Your Weight Be Different?

Gravity exerts a force of attraction between any two objects—the Earth and you, for example. Its strength depends on the amount of mass (matter) each one has and on how far apart their centers are. The more mass something has, the more gravity it has. The farther apart two objects are, the weaker the force between them becomes. So, if you visited another world, your weight would change because the mass and size of that world would differ from Earth’s, which means that the force of gravity acting on you would be different too. Your mass, however, would not change.

Q:

## What’s the difference between mass and weight?

A:

Mass is the amount of matter in an object and weight is the measurement of the gravitational pull on an object. The mass of an object is the same no matter where it is, but the weight of an object changes with the location of that object. ... more

# Watch a Video

## Weight

Explore the relationship between drag and weight by experimenting with air resistance and vacuums.

## Did You Know?

You weigh less on the second floor of a building than you do on the first floor, because as you go up, your distance from the center of the Earth increases. The difference in your weight is extremely small though – about the weight of a small insect.

## Pop Quiz

Does gravity exist in space?

A) True
B) False

Gravity exists everywhere.  It holds solar systems and galaxies together. Gravity from Earth keeps the Moon and spacecraft orbiting around it.  Gravity decreases with distance, so the farther you are away from a celestial body the less gravity you feel.