Navigation Novelty: Compass Quiz

A compass' small, lightweight magnet, or needle, is balanced on a nearly frictionless pivot point.

One end of the needle is often marked "N," for north, or colored in some way to indicate that it points toward north.

The Earth's diameter is about 8,000 miles (12,875 kilometers), which is a long way for the planet's magnetic field to go before affecting your compass. That's why a compass has a lightweight magnet and a frictionless bearing -- otherwise, there just isn't enough strength in the Earth's magnetic field to turn the needle.

Convection caused by heat radiating from the Earth's core, along with the rotation of the Earth, may be what causes the liquid iron of the Earth's core to rotate and create a magnetic field.

You can magnetize a needle by stroking it with a magnet 10 to 20 times.

Because of the trouble encountered by magnetic compasses on moving platforms, many ships and planes instead use gyroscopic compasses.

Not only do magnetic compasses correct themselves slowly when the platform turns, but they also must be kept level to work properly.

A spinning gyroscope inside the compass, fueled by a small motor, keeps the needle pointing north even in rough seas or turbulence.

The axis of a gyrocompass is pointed north using a magnetic compass as a reference. Magnetic compasses are also periodically used to correct any errors picked up by the gyrocompass.

To make your own compass, all you have to do is place a magnetized needle on a lightweight floating material in a dish of water. The needle will slowly point toward north.