Gravity: the force that keeps you grounded
Gravity is a force that pulls objects toward each other. The bigger an object is, the more gravity it has. Earth is big, so it has strong gravity that pulls everything, including you, toward its center. That’s why when you jump, you come right back down.
On Earth, you might jump about 1 or 2 feet high.
But what if gravity wasn’t so strong?
The moon has less gravity
The Moon is only about one-sixth the size of Earth, so it has much less mass. That means it also has weaker gravity, It’s only 1/6 as strong as that of Earth.
If you weigh 90 pounds on Earth, you’d weigh only 15 pounds on the Moon. You’re not actually lighter, but the gravitational pull is weaker, so your body feels lighter and is easier to move.
What happens when you jump on the Moon?
If you jumped on the Moon:
You could jump 6 times higher than on Earth. A 2-foot jump would become 12 feet.
You’d float in the air for longer—about 2 to 3 seconds instead of just one.
Moving would feel like bouncing in slow motion, just like astronauts.
That’s why astronauts walking on the Moon look like they’re bouncing around, because they are.
What did the astronauts experience?
When Neil Armstrong and Buzz Aldrin, the astronauts, first walked on the Moon in 1969, they knew that walking normally didn’t work well. So, they used a special hopping motion to move around. Their jumps looked high and floaty, but they were using very little effort.
The science behind gravity
The force of gravity is described by Isaac Newton’s Law of Universal Gravitation.
In his own words: "The force of gravity is proportional to the product of the masses and inversely proportional to the square of the distance between them."
That’s a little difficult to understand. Let’s paraphrase it:
Every particle of matter in the universe attracts every other particle with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centers.
Let’s simplify it further:
Every object in the universe attracts every other object with a force that's stronger when the objects are larger and closer together.
Here's a breakdown:
"Every object in the universe attracts every other object": According to Newton's law, all objects with mass exert a gravitational pull on each other.
"With a force that's stronger when the objects are larger": The gravitational force increases with the product of the two masses.
"And closer together": The force becomes stronger as the distance between the objects decreases (specifically, it increases as the inverse square of the distance).
Because the Moon has less mass and a smaller radius, its gravitational pull is much weaker than Earth’s.
The actual formula
Where:
F is the gravitational force,
G is the gravitational constant,
m1 and m2 are the two masses,
r is the distance between the centers of the two masses.
