A bar magnet is just what it sounds like – a magnetized bar. One end has a south pole, and the other end has a north pole. For example, a hand compass is made with a bar magnet.
A spinning electron behaves like a tiny bar magnet. An electron orbiting a nucleus also behaves like a tiny bar magnet.
We can think of matter in this way: It can act as if it has many tiny bar magnets inside. In many cases, those bar magnets point in opposite directions. Then there is no magnetism. In other cases, those bar magnets point in different, random directions. Then there is a little magnetism.
In magnets made from iron, those little bar magnets all line up in the same direction. In other words, all the north poles are pointing in the same direction. The iron is strongly magnetized.
Our home, the magnet
The Earth is a giant magnet. Its molten, or hot liquid, outer core and its cooler layers are made of materials such as iron that turn the Earth into a magnet.
The North Pole and the South Pole are the opposite ends of the planetary magnet, just as with a smaller bar magnet.
The Earth’s liquid iron outer core is constantly moving. This produces charged particles in the core. The moving charge in the core produces a magnetic field. The iron and other materials in the layers of the Earth also help form the Earth’s magnetic field.
A compass works because opposite poles attract. The south pole of the thin bar magnet inside the compass always points to the north magnetic pole of the Earth.
Magnetism from the Earth’s core extends for thousands of miles around the planet. It acts as a giant protective shield against charged particles blowing out from the sun in the solar wind. This magnetic region is called the magnetosphere.
The magnetosphere bounces most of the sun’s charged particles back into space. It also protects spacecraft orbiting the Earth from cosmic radiation.
The aurora australis, or the southern lights, turn the skies red over Australia. When charged particles from the sun hit the Earth’s magnetic field, they can create colorful auroras. The aurora borealis, near the North Pole, and the aurora australis, near the South Pole, create the most dramatic displays.
The Earth’s magnetic field is similar to the magnetic field of a bar magnet.