The inner core is the Earth’s deepest layer, and it is a solid iron ball that is approximately 1,500 miles in diameter. Although it is extremely hot, the iron cannot melt due to the high pressure. The inner core also consists of nickel and sulfur and smaller amounts of elements other than iron.
The metals are compressed tightly together and are forced to vibrate as solid. The tremendous pressure causes the inner core to form into a solid mass. The high temperatures reach up to 9,000 F, and the pressures are almost 45 million pounds per square inch, which is 3 million times the air pressure at sea level. Beneath the crust’s surface, the inner core extends 3,200 miles further. Most of this layer comprises iron, but scientists theorize that it also contains other elements such as sulfur, potassium and carbon. The inner and outer cores create the Earth’s magnetic field. The Earth’s rotation causes the core to spin, which leads to the creation of an effect that maintains the Earth’s magnetic field. The inner core is unattached to the mantle, and it makes up 1.7 percent of the Earth’s mass. Indirect methods, such as seismic tomography, are used to study the core and determine its properties.