Course Learning

Have you ever wondered why when you throw something into the air it falls straight back to the ground?

This is because of gravity, an invisible force which acts on objects, pulling them towards the centre of the earth.

It is gravity that keeps us firmly on the ground and what makes objects fall.

Without gravity, everything on Earth would float away.

Gravity acts on all objects. The larger the object, the greater the gravitational pull it has.

There is less gravity on the Moon than there is on Earth because the Moon is smaller than the Earth.

If you jumped on the Moon, it would take longer to return to the surface than if you jumped on Earth.

The Sun's gravitational pull keeps all of the planets in orbit.

The Earth's gravity keeps us just the right distance away from the Sun.

Gravity also keeps the Moon in orbit around the Earth.

The Moon's gravitational pull affects the oceans on Earth, as the Moon pulls water towards it, causing a change in the tides.

Gravity creates stars and planets by pulling together rock and gas.

Without gravity, it would make everyday activities like eating and drinking very difficult. Our food and drink would simply float away from our plates and cups, which is what occurs in the weightlessness of the International Space Station (ISS).

The English scientist, mathematician and philosopher Sir Isaac Newton discovered gravity.

Newton saw an apple fall from a tree and began to think that there must be a force that exists, pulling the apple to the ground.

He carried out many experiments and he worked out that the force of gravity was linked to how heavy objects were and how far apart they are.

The heavier the object, the stronger the gravitational pull.

The closer we are to that object, the more we feel that gravitational pull.

• Jupiter is a much larger planet than Earth it has much more gravitational pull, so you would weigh more on Jupiter than you do on Earth!
• Gravity actually causes you to shrink. Astronauts who have gone into space where the gravitational pull is less have returned to Earth 2cm taller than when they left!
• The gravity on the ISS is about 90% of the gravity we feel on the Earth's surface, but because it's in orbit it provides the feeling of weightlessness.
• A gravitational wave detected in 2015 occurred because of two merging black holes that emitted 50 times the power of all the stars in the Universe.
• The physicist Albert Einstein used Sir Isaac Newton’s theories on gravity to develop his famous theory of relativity.
• The Sun has a much wider gravitational field than Earth’s. It holds all the planets, moons and asteroids in our Solar System in orbit around it.

Black holes have such a strong gravitational pull that not even light can escape them!