Non-contact forces: gravity and magnetism
Non-contact forces act without touching the object. We can't see them, so they are also called invisible forces.
Gravity is a force that pulls objects towards each other. Everything that has mass has gravity, and the more mass, the stronger it is. The Earth has so much mass that it pulls everything towards its centre: that is why leaves fall from trees in autumn. The Earth's gravity also keeps the Moon, space stations and satellites in orbit around it. The Moon has less mass, so its gravity is weaker: astronauts can jump much higher there!
A magnet makes a non-contact force called magnetism. It can attract (pull) or repel (push away). Magnets attract some metals: iron, nickel and cobalt. Every magnet has two poles, a north pole and a south pole. Magnetism is related to electricity.
different poles attract
the same poles repel
The needle of a compass is a tiny magnet. The Earth acts like a giant magnet, so the needle always points north!