Earth's magnetic poles have always been dynamic, typically swapping north for south every 300,000 years or so according to geologic records. The last complete transition occurred approximately 780,000 years ago. Scientists have kept more accurate records of the poles' location over the past 150 years using instruments designed by Carl Freidrich Gauss. Their data shows the North Pole has been wandering across the Canadian arctic, by about 40 km/year. The magnetic field itself has been fading in strength and current measurements indicate it is 10% weaker than all previous measurements. Computer models show that our magnetosphere is the result of the outer core's quickly rotating sea of liquid iron and accompanying simulations demonstrate the peculiar changes to Earth's magnetic fields during a transition. Theories abound as to what may happen to Earth itself during a transition, ranging from disappearing completely and irradiating all life to becoming violently skewed and rendering the Northern Lights across the globe.