Same throw, four planets
Throw the same ball on Earth, the Moon, Mars and Jupiter and watch what gravity does.
Imagine four friends on four different worlds. At exactly the same moment, they all throw a ball the same way: same speed, same angle. Will the balls land in the same place?
Race them
Press the button to launch four balls at once. Each colour is a different world.
The Moon ball floats on and on. The Jupiter ball smacks into the ground almost straight away. The only thing that changed is gravity.
What is gravity, again?
Gravity is a pull. Every planet and moon pulls things toward its middle. Bigger, heavier worlds usually pull harder.
Scientists measure the pull with a number called g. It tells you how much faster a falling thing gets every second.
| World | g (m/s²) | Compared to Earth |
|---|---|---|
| Moon | 1.62 | about 1/6 |
| Mars | 3.71 | a bit more than 1/3 |
| Earth | 9.81 | 1× |
| Jupiter | 24.79 | about 2.5× |
Why weaker gravity means longer throws
A thrown ball keeps moving forward until it hits the ground. Gravity decides how quickly that happens.
- On the Moon, gravity pulls gently, so the ball takes a long time to come down. More time in the air means more distance.
- On Jupiter, gravity pulls hard. The ball's upward speed disappears fast, and it is back on the ground in under a second.
At 10 m/s and 45°, here is what happens:
| World | Time in the air | Distance |
|---|---|---|
| Moon | 8.9 s | 63.2 m |
| Mars | 4.0 s | 28.4 m |
| Earth | 1.6 s | 11.5 m |
| Jupiter | 0.7 s | 5.2 m |
If gravity is 6 times weaker, the ball goes about 6 times farther. Distance and gravity are opposites: when one goes down, the other goes up by the same amount.
Wait, Jupiter doesn't have any ground!
True. Jupiter is a giant ball of gas, with no solid surface to stand on. In Launch Lab we built an imaginary floating launch pad in its clouds. The gravity number is real, though. If you could stand there, you'd feel about two and a half times heavier.
Real astronauts, real bounces
When Apollo astronauts walked on the Moon, they found that bouncing like kangaroos was often easier than walking. Each hop carried them much farther than it would on Earth, for exactly the reason you just saw.
Engineers sending rovers to Mars use these same ideas. Every landing is planned with Mars's own value of g.