Gravity is a force.
It is an invisible force. That means you cannot see it.
Gravity pulls things toward each other.
A planet pulls things toward its center.
Earth is a planet. Earth pulls you toward its center.
Jump up. You do not float off into space.
You land back on the ground.
Drop a ball. It falls down.
Earth's gravity does that.
Earth's gravity keeps you on the ground. It makes things fall.
Anything that has mass also has gravity.
Things with more mass have more gravity.
Gravity gets weaker when things are far apart.
Things that are close together pull on each other more strongly.
Earth has a lot of mass.
All of Earth's mass pulls on the mass in your body.
That pull gives you weight.
On a planet with less mass than Earth, you would weigh less than you do here.
Here is a surprise. You pull on Earth, too, with the same force.
But Earth is so much bigger than you that your pull does not really change our planet.
The Sun's gravity keeps all the planets in orbit around the Sun.
Gravity keeps the Moon in orbit around Earth, too.
The Moon's pull pulls the seas toward it.
That causes the ocean tides.
We could not live on Earth without gravity.
The Sun's gravity keeps Earth in orbit around it.
That keeps us at a good distance to enjoy the Sun's light and warmth.
Gravity holds down the atmosphere and the air we need to breathe.
Gravity is what holds our world together.
Gravity is the force by which a planet or other body draws objects toward its center.
It is also a force of attraction that exists between any two masses, any two bodies, and any two particles.
Gravity is not just the attraction between objects and Earth. It is an attraction that exists between all objects, everywhere in the universe.
Scientists are honest about one big point: we do not know what gravity is in any fundamental way. We only know how it behaves. Some scientists think it is made up of particles called gravitons, which travel at the speed of light.
Sir Isaac Newton discovered that a force is required to change the speed or direction of movement of an object.
He realized that the force called gravity must be what makes an apple fall from a tree. It also lets humans and animals live on the surface of our spinning planet without being flung off.
He worked out that gravity forces exist between all objects.
The story that Newton discovered the laws of gravity just by watching apples fall from a tree is probably a myth. He did do his work on gravity while at a farm, but that is about as much as can be proven.
Anything that has mass also has gravity. Objects with more mass have more gravity.
Gravity also gets weaker with distance. The closer objects are to each other, the stronger their gravitational pull is.
Newton's law of gravity is a mathematical description of the way bodies attract one another, based on many scientific experiments and observations. It says the force of gravity grows with the product of the two masses, and shrinks with the square of the distance between their centers.
The effect of gravity extends from each object out into space in all directions, and for an infinite distance. But its strength reduces quickly with distance.
That is why you never notice the Sun's gravity pulling on you. The pull is so small at the distance between Earth and the Sun. Yet it is the Sun's gravity that keeps Earth in its orbit.
Earth's gravity comes from all its mass. All that mass makes a combined gravitational pull on all the mass in your body. That is what gives you weight.
If you were on a planet with less mass than Earth, you would weigh less than you do here.
You exert the same gravitational force on Earth that it does on you. But because Earth is so much more massive than you, your force does not really have an effect on our planet.
Gravity is what holds the planets in orbit around the Sun and what keeps the Moon in orbit around Earth.
The gravitational pull of the Moon pulls the seas towards it, causing the ocean tides. We are never aware of the pull of lunar gravity on our own bodies, but the Moon's gravity is responsible for the ocean tides on Earth.
Gravity also creates stars and planets by pulling together the material from which they are made.
Albert Einstein described gravity as a curve in space that wraps around an object, such as a star or a planet. If another object is nearby, it is pulled into the curve.
Gravity not only pulls on mass. It also pulls on light. Einstein discovered this principle. If you shine a flashlight upwards, the light will grow imperceptibly redder as gravity pulls it. You cannot see the change with your eyes, but scientists can measure it.
Black holes pack so much mass into such a small volume that their gravity is strong enough to keep anything, even light, from escaping.
Gravity is slightly stronger over places with more mass underground than over places with less mass.
NASA uses two spacecraft to measure these variations in Earth's gravity. These spacecraft are part of the Gravity Recovery and Climate Experiment, called GRACE.
The GRACE mission helps scientists create maps of gravity variations on Earth. GRACE detects tiny changes in gravity over time. It monitors changes in sea level, and it can detect changes in Earth's crust brought on by earthquakes.
Gravity matters down here, too. It holds down our atmosphere and the air we need to breathe, and the Sun's gravity keeps Earth at a comfortable distance to enjoy the Sun's light and warmth.
NASA Space Place — NASA Science for Kids, “What Is Gravity?” https://spaceplace.nasa.gov/what-is-gravity/en/ (article last updated December 17, 2020).
NASA StarChild, a service of the High Energy Astrophysics Science Archive Research Center (HEASARC) at NASA Goddard Space Flight Center, “What is gravity?” http://starchild.gsfc.nasa.gov/docs/StarChild/questions/question30.html
Checked November 2, 2026