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Core of the Earth
by FRASER CAIN on MARCH 9, 2009
 
The Earths interior (University of Chicago)

Scientists believe that deep down inside the Earth, there’s a huge ball of liquid and solid iron. This is the Earth’s core, and it protects us from the dangerous radiation of space.
When the Earth first formed, 4.6 billion years ago, it was a hot ball of molten rock and metal. And since it was mostly liquid, heavier elements like iron and nickel were able to sink down into the planet and accumulate at the core. The core is believed to have two parts: a solid inner core, with a radius of 1,220 km, and then a liquid outer core with a radius of 3,400 km. The core is through to be 80% iron, as well as nickel and other dense elements like gold, platinum and uranium. The inner core is solid, but the outer core is a hot liquid. Scientists think that movements of metal, like currents in the oceans, create the magnetic field that surrounds the Earth. This magnetic field extends out from the Earth for thousands of kilometers, and protect us from the solar wind blowing from the Sun. Without this magnetic field, the solar wind would blow away the lightest parts of our atmosphere, and make our environment more like cold, dead Mars.

Text adapted. Original version available at: http://www.universetoday.com/26700/core-of-the-earth/