The Earth's inner core is the Earth's innermost part and according to seismological studies, it has been believed to be primarily a solid ball with a radius of about 1220 kilometers, or 760 miles (about 70% of the Moon's radius).[1][2] It is composed of an iron–nickel alloy and some light elements. The temperature at the inner core boundary is approximately 5700 K (5400 °C).[3]
