Deep beneath our feet, at a staggering depth of over 5,100km, lies Earth’s inner core—a solid ball of iron and nickel that plays a crucial role in shaping the conditions we experience on the surface. In fact, without it we’d be unlikely to even exist. Deep beneath our feet, at a staggering depth of over 5,100km, lies Earth’s inner core—a solid ball of iron and nickel that plays a crucial role in shaping the conditions we experience on the surface. In fact, without it we’d be unlikely to even exist. Earth Sciences Phys.org – latest science and technology news stories