North Pole, South Pole: The Quest to Understand Earth's Magnestism

Earth's magnetic shield is essential to life on Earth because it deflects the sun's violent and toxic rays. Magnetism itself has been, throughout human history, the main method of navigation – and is even used by migrating birds and animals.

But what is the source of Earth's magnetism? What mysterious force makes compass needles point to the poles, and dangerous particles from the sun veer back into space?

For centuries this question absorbed and often obsessed the world's greatest scientific minds. Albert Einstein called it 'the last great unsolved mystery of science'. Each scientist contributed a piece of the puzzle – but it was only in the 21st century that the code was finally cracked.

And there was another astonishing twist to come…