<P> The Earth 's inner core is the Earth 's innermost part . It is primarily a solid ball with a radius of about 1,220 kilometres ( 760 miles ) , which is about 70 % of the Moon 's radius . It is composed of an iron -- nickel alloy and some other elements . The temperature at the inner core 's surface is approximately 5,700 K ( 5,430 ° C ) , which is about the temperature at the surface of the Sun . </P>
what is the inner core of the earth made from
iron -- nickel alloy some other elements