what is the inner core of the earth made from
some other elements iron–nickel alloy an iron–nickel alloy
title: Inner core text: Inner core The Earth's inner core is the Earth's innermost part. It is primarily a solid ball with a radius of about , 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 or 9806 °F, which is about the temperature at the surface of the Sun. The Earth was discovered to have a solid inner core distinct from its molten outer core in 1936, by the Danish seismologist Inge Lehmann, who deduced its presence by studying seismograms from earthquakes in New title: Inner core text: feature that was present during the planet's formation, but a feature younger than the Earth (the Earth is about 4.5 billion years old). Inner core The Earth's inner core is the Earth's innermost part. It is primarily a solid ball with a radius of about , 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 or 9806 °F, which is about the temperature at the surface of the Sun. The Earth was discovered to have a solid inner core distinct from title: Structure of the Earth text: of iron–nickel alloy was subjected to the corelike pressures by gripping it in a vise between 2 diamond tips (diamond anvil cell), and then heating to approximately 4000 K. The sample was observed with x-rays, and strongly supported the theory that Earth's inner core was made of giant crystals running north to south. The liquid outer core surrounds the inner core and is believed to be composed of iron mixed with nickel and trace amounts of lighter elements. Recent speculation suggests that the innermost part of the core is enriched in gold, platinum and other siderophile elements. The matter that title: Inner core text: Based on the relative prevalence of various chemical elements in the Solar System, the theory of planetary formation, and constraints imposed or implied by the chemistry of the rest of the Earth's volume, the inner core is believed to consist primarily of a nickel-iron alloy. Pure iron was found to be denser than the core by approximately 3%, implying the presence of light elements in the core (e.g. silicon, oxygen, sulfur) in addition to the probable presence of nickel. Further, if the primordial and mostly "fluid" (still forming) earth contained any significant mass(es) of elements denser than iron and nickel, title: Inner core text: would be found to be homogeneous, because the solid inner core was originally formed by a gradual cooling of molten material, and continues to grow as a result of that same process. Even though it is growing into liquid, it is solid, due to the very high pressure that keeps it compacted together even if the temperature is extremely high. It was even suggested that Earth's inner core might be a single crystal of iron. However, this prediction was disproved by observations indicating that in fact there is a degree of disorder within the inner core. Seismologists have found that