Physicists do know that the Earth acts very much the same way that electrons do. Just as every electron in an atom orbits around the nucleus of the atom, the Earth orbits the sun once a year. Just as every electron spins around its own axis like a spinning top, the earth spins round its own axis every day. The reason the needle of a compass lines up in a north-south direction is because the Earth is surrounded by its own magnetic field. It is not clear to scientists why the Earth acts like a magnet. It may be related to strong magnetic currents at the earth’s core, or it may be related to its rotation or orbital motion around the sun.

The lithospheric magnetic anomalies (at the right) show a modeled image of Earth's magnetic field variations created as a result of science satellites. The color bars indicate areas with positive and negative magnetic fields.