The immense pressure from the other parts of the planet keep the extremely hot iron of the Earth's inner core from melting. The iron in the inner core maintains a temperature of around 9,000 to 13,000 degrees Fahrenheit.
The inner core has a round shape with a thickness of about 750 miles. Since the core consists of a large iron ball, the entire planet is essentially a magnet with poles on the top and bottom. The magnetic field helps the Earth avoid collision with particles from the sun.
The layer outside the inner core is the outer core, with a thickness of approximately 1,430 miles. The outer core consists primarily of iron and nickel, two valuable metals found in abundant amounts on the planet. While these metals exist in solid form on the Earth’s surface, they create a molten alloy in the outer core. The outer core’s alloy is incredibly hot, having a temperature that ranges from 7,200 to 9,000 degrees Fahrenheit. The metals in the core constantly move, as the core rotates regularly. The liquid outer core changes the location of the magnetic polar regions as it moves.
The heaviest materials on the planet descended into the inner core during the creation of the planet billions of years ago. Air, water and other light, less dense materials remained near the crust.