Question

How did the earth come to have a molten iron core?

Asked by: Ralph Wiley

Answer

Four and a half billion years ago, Earth (and the other planets in the Solar System) formed when smaller bits of matter in solar orbit came together gravitationally. As a result of those multiple collisions the kinetic energy of motion was converted to heat energy, resulting in a hot, molten mass that would become our Earth.

While in this hot, fluid state, the denser, heavier material (iron and nickel) settled to the center and the less dense rocky material floated nearer the surface, resulting in today's iron/nickel core.

As the Earth radiated energy into space, the outer layers cooled first. The core, being insulated by Earth's outer layers, took longer to cool. That is not the complete story, however. In addition to the initial energy of formation, there are radioactive elements in the Earth with long half lives that continue to release energy. This energy cannot immediately escape into space either, and also accounts for the Earth's hot, molten interior.

Answered by: Paul Walorski, B.A., Part-time Physics/Astronomy Instructor

Search

Loading



Sponsors

USC University of Southern California Dornsife College Physics and Astronomy Department McMaster University Physics and Astronomy Department

Science Quote

'If you would be a real seeker after truth, it is necessary that at least once in your life you doubt, as far as possible, all things.'

René Descartes
(1596-1650)

Deal of the Day

Image of Shark Tooth Fossil in Matrix. Click on this image for more info. Shark Tooth Fossil in Matrix
Regular Price: $39.95
Today's Price: $15.00
Superb shark fossil specimen for the science classroom! Buy it now! Deal ends at midnight!

Top Selling

Here are our physics & astronomy bestsellers:
Mini Plasma Ball
Slide Making Kit
Top Secret - Spinning Top
Wood Grain Newtons Cradle
Deluxe 3D Mirascope
Solar Radiometer
Periscope
Solar Science 4M Kit
Ultimate Chemistry Set CHEM C3000
3D Magnetic Field Tube