Earth's magnetic field can change ten times faster than previously thought, according to new research. It has had our backs for billions of years - and is caused by a swirling sea of iron 17,400 miles beneath the surface.
But it's unpredictable. Jules Verne imagined it was an ocean populated by weird and wonderful creatures when he wrote Journey to the Centre of the Earth.
Now, more than 150 years later, the core of our planet is beginning to give up its secrets. British scientists have simulated its behaviour over the past 100,000 years - showing how it has influenced shifts in the magnetic field.
Like the invisible force shield around the Death Star in Star Wars, this protects us from radiation in the solar wind. As a tool for navigation
Read more on mirror.co.uk