Scientists have determined that the center of the earth is 6371 km below the surface. But how has this been determined? Many people might answer that question by saying scientists can drill into the Earth with machines. However, the drilling rigs that scientists use can only drill about 20 km in the Earth which is not very deep! In other words, we can only drill into upper part of the crust of the earth. Extremely high temperatures and pressures within the Earth make drilling into it very difficult