<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 light elements . The temperature at the inner core boundary is approximately 5700 K ( 5400 ° C ) . </P>
<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 light elements . The temperature at the inner core boundary is approximately 5700 K ( 5400 ° C ) . </P>
the core of the earth is mostly composed of
the core of the earth is mostly composed of
an iron -- nickel alloy
an iron -- nickel alloy