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.
The lodestone acted just like the needle on a
compass. 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.
Discovery Education Science
© 2007 Discovery Communications, LLC
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An Ancient Compass
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 r i g h t it's a south magnetic pole! In other words, the magnetic pole near
Earth's North Pole is actually a south magnetic pole.
Discovery Education Science
© 2007 Discovery Communications, LLC
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