Why Does The Earth Have Layers?

...or why do we live on an onion made of magma?

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Thanks to Miles Traer and Mike Osborne for geophysics help on this one!

Why does Earth have a liquid core, and how do we know?
http://scienceblogs.com/starts....withabang/2011/09/28

How many pennies would you have to stack to melt the one on the bottom? http://www.reddit.com/r/asksci....ence/comments/2g8jj9

Why are the inner planets rocky and the outer ones are gas giants?
http://www.quora.com/Why-are-t....he-inner-planets-roc

Produced for PBS Digital Studios

Joe Hanson - Host and writer
Joe Nicolosi - Director
Amanda Fox - Producer, Spotzen IncKate Eads - Associate Producer
Katie Graham - Director of Photography
Andrew Matthews - Editing/Motion Graphics
John Knudsen - Gaffer
Dalton Allen - Post-production Intern

Theme music:
"Ouroboros" by Kevin MacLeod

Stock images via Shutterstock

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