A magnet attracts other magnets, and it also attracts some iron and steel things, such as pins and paper clips. Every magnet has a north pole and a south pole. Opposite poles attract each other, and the same poles push each other away. Some stones are natural magnets. Two kinds of magnets exist: permanent magnets and temporary magnets. Here is a rule to keep. Magnets are not for mouths or small children. Loose magnets can hurt children if they are swallowed. If a child swallows more than one, the magnets can pull together inside the body and cause serious damage.

People have used a compass for hundreds of years to find their way. Early Chinese compasses were oriented to point south rather than north like today's compasses. Miners in search of jade appear to have used south-pointing spoons. A lodestone compass was used in navigation as early as 1086, and compasses were used to navigate by the 1100s. In time, 32 points of direction were added to the compass card. A magnetic compass has a magnetized needle that turns to line up with Earth's magnetic field. In the southern hemisphere the weight on a compass needle needs to be on the north end, so the needle stays horizontal and free to rotate. Some compasses, such as a solar compass that uses the Sun, do not use Earth's magnetism to indicate direction.

The needle of a compass lines up with Earth's magnetic poles. These are not the same as Earth's geographic North and South Poles. Magnetic declination is the angle between magnetic north and true north. A mile or two away it may be considerably different, requiring a different correction. Edmond Halley carried out the first magnetic declination survey and published a chart of his findings two years later. Halley used his view of the planet to explain why declination slowly changes over time. Declination is unreliable near the poles, and at the magnetic poles a compass does not show direction. As of November 2026, receivers from the global positioning system (GPS) have begun to take the place of compasses.

Now let's turn to electricity, and how it came to be linked to magnets. Magnetism is caused by the motion of electric charges. In 1820 Hans Christian Ørsted's discovery showed that electricity and magnetism are related. An electric current creates a magnetic field. Ampère found that parallel wires carrying currents in opposite directions repel each other. François Arago found that unmagnetized iron filings orient themselves in a circle around a copper wire carrying current. Michael Faraday discovered electromagnetically induced currents in 1831. A changing magnetic field near a conductor can create an electric current in the conductor. The currents depend on the rate at which the field changes.

Let's end up in space. We have looked at Earth up close. Now look at what lies above it. Earth's magnetic field begins in its core. Earth is surrounded by a large magnetic shield called a magnetosphere. It protects us from harmful charged particles in space. The Sun sends out a flow of charged particles called the solar wind. The solar wind creates temporary cracks in Earth's magnetic shield, letting some energy reach Earth's surface daily. Since these intrusions are brief, they do not cause significant issues. Direct observations of Earth's magnetic field extend back just a few centuries, so scientists rely on indirect evidence.

Words to know

• declination: compass angle
• hemisphere: half of Earth
• lodestone: natural magnet
• magnetosphere: magnetic shield