Each planet is a little different on the inside. And what’s inside a planet can shape what’s on the outside, too. That’s what I found out from my friend Steve Reidel, a WSU geologist.
“Well, there’s the rocky planets,” he said. “Then there are the big, gas giants.”
Rocky planets, like Earth, are wrapped in a thick crust. Beneath Earth’s crust is the mantle. The mantle is quite solid, but it actually behaves more like a fluid. It flows and deforms. It’s similar to Silly Putty, but a really strong version of Silly Putty. It’s about 1,800 miles thick. It is also the main source of Earth’s volcanoes…
See Dr. Universe’s complete response here.