Hard-Boiled Earth

What do planet Earth and a hard-boiled egg have in common? They both have three layers. Like an egg, Earth has a hard outer shell called the crust. This is the part of Earth on which we live. Under the crust is a layer of hot rock called the mantle. The mantle is like the white of a boiled egg. There is an upper mantle and lower mantle.

The yolk is at the center of an egg. At the center of Earth is a layer called the core. The core is split into two parts. The outer core is made of liquid metal. The inner core is solid metal.