BBC Horizon: The Core documentary. How do we reach the center of the Earth to gain knowledge about its inner workings? This documentary explores the journey from the surface of the Earth to its center as documentary film makers travel to the worlds deepest laboratory more than 2 miles below the Earth surface where solid rock is pliable like plastic. The farthest depths at which humans can excavate will most probably never exceed the Earths crust or about 0.3% towards the Earths center which of course means we will never actually see the mantle never mind the core or outer core with the naked eye. The environment is simply way too extreme since the core’s average temperature is around 5,400°c and surrounding pressure is estimated to be 50 million PSI which is pretty hard to imagine (average car tyre pressure is 30 PSI),even when in comparison with the depths of the deepest oceans.
To look beyond the Earths crust we have to turn to seismology, the science of measuring seismic waves produced by Earthquakes. This has revealed that the outer core is completely molten metal with a viscosity not much thicker than water and thousands of miles deep. Studying the outer core has also shown its motion is what powers the magnetosphere, an invisible shield around the Earth protecting us from the suns dangerous charged particles.
No matter how much we know about the Earth there is always something new to be discovered science has proven.