An Ancient Compass

A compass can help people find their way on land, on sea, and in the air. The Chinese made the first compasses about 2,500 years ago. To make a compass, the Chinese used a mineral called lodestone. They shaped the lodestone into the form of a spoon.

They then placed the lodestone spoon on a flat plate made of bronze. The plate represented Earth. The Chinese marked the directions on the plate, including north, south, east, and west. The bowl of the spoon always rested in the center. The handle of the spoon always pointed toward the south.

A compass uses the Earth’s magnetic field to The lodestone acted just like the needle on a compass. show direction. One end of a needle always points south, and the other end always points north. Lodestone and a compass needle act this way because they are magnets. A magnet is any material that attracts iron or something that contains iron.

You probably have a magnet in your home. There may be a magnet holding your last science test on the refrigerator. Magnets can attract or repel each other. For example, the magnet on the refrigerator is attracted to the steel metal in the door. This happens because steel is made from iron. Magnets also attract another metal called nickel.

Earth’s core, or center, is made of iron and nickel. These two metals make Earth act like a giant magnet. Like all magnets, Earth has two poles. One is a north pole. The other is a south pole. A pole of one magnet attracts or repels the pole of another magnet.

If the two poles are alike, they will repel each other. For example, if you bring the south poles of two magnets close together, the poles will repel each other. However, if the two poles are different, they will attract each other. This is what happens when you bring the north pole of one magnet close to the south pole of another magnet.

All compasses, including the ancient Chinese ones, work because of what happens between the poles of two magnets. One end of a compass needle points north. This end of the compass needle is the needle’s north pole. If the compass needle’s north pole points north, what kind of magnetic pole must be in Earth’s north? That's right—it’s a south magnetic pole! In other words, the magnetic pole near Earth’s North Pole is actually a south magnetic pole.