Why do compass needles point north--but not quite north? What guides the migration of birds, whales, and fish across the world\'s oceans? How is Earth able to sustain life under an onslaught of solar wind and cosmic radiation? For centuries, the world\'s Great scientists have grappled with these questions, all rooted in the same phenomenon--Earth\'s magnetism.
Over 2,000 years after the invention of the compass, Einstein called the source of Earth\'s magnetic field one of greatest unsolv.
Why do compass needles point north--but not quite north? What guides the migration of birds, whales, and fish across the world\'s oceans? How is Earth able to sustain life under an onslaught of solar wind and cosmic radiation? For centuries, the world\'s Great scientists have grappled with these questions, all rooted in the same phenomenon--Earth\'s magnetism
