Gravity on other planets simulator

What this simulator shows

Gravity pulls every object toward a planet or moon, and the pull is stronger on some worlds than others. Choose a world and a mass of 1, 2, 5 or 10 kg. The spring scale stretches to show the weight in newtons, with a dashed blue line marking the Earth reading for comparison. The jump picture shows how high a child who can jump 50 cm on Earth would go with exactly the same push off the ground, and Jump plays it at the real speed.

• Mass is how much matter something has, measured in kilograms. It is the same everywhere.
• Weight is the force of gravity on that mass, measured in newtons. It changes from world to world.
• Weight = mass × gravitational field strength. On Earth that is about 9.8 newtons for every kilogram.
• With weaker gravity, the same jump goes higher and lasts longer: about 3 m on the Moon.

Why hands-on helps

In everyday speech, "weight" means kilograms or pounds, so the science meaning can feel strange. Holding the mass fixed while the scale reading changes makes the difference visible: the same 10 kg block stretches the spring a lot on Jupiter and hardly at all on Pluto. The jump comparison gives children a feel for what weaker gravity would be like.

Common misconceptions

The biggest mix-up is between mass and weight. An astronaut on the Moon still has the same mass; there is just less gravity pulling on it. Another common idea is that there is no gravity in space. Astronauts on the International Space Station float because they and the station are falling around Earth together, not because gravity has disappeared. Some children think the Moon has no gravity at all, or that bigger planets always have stronger gravity at the surface. Saturn is far more massive than Earth, but its gravity at the cloud tops is only a little stronger, because it is so wide.

Jupiter, Saturn, Uranus and Neptune have no solid surface, so their values are for the cloud tops. Pluto is a dwarf planet, included for comparison.

A 10-minute gravity activity

• Ask: "If you went to the Moon, would you be lighter, heavier or the same?" Note the answer.
• Hang the 10 kg mass on Earth and read the scale. Switch to the Moon.
• Ask: "Did the block lose any of its stuff?" Talk about mass and weight.
• Press Jump on the Moon and on Jupiter. Compare heights and times.
• Find the world with the strongest pull, then the weakest.

Where this fits in school

• US, grade 5: NGSS 5-PS2-1 asks students to argue that Earth's gravity pulls objects down.
• US, middle school: NGSS MS-PS2-4 asks students to argue that gravitational forces are attractive and depend on the masses of the objects.
• England, Year 5: pupils explain that unsupported objects fall toward Earth because of gravity.
• England, Key Stage 3: pupils learn that weight = mass × gravitational field strength (g), and that g is different on other planets and stars.

Learning more

Forces and space are part of Eurekami's science skill map, with lessons that explain ideas like mass and weight using live diagrams. Daily practice mixes in a few science questions so they stay fresh.