AY 101 Lecture Notes - Lecture 12: Terrestrial Planet, Red Color, Volcanism
Document Summary
Over time, solar heat boiled off the air, causing much of the water to be lost to space. These small worlds cooled rapidly after forming: no geologic activity means these faces have been largely unchanged for billions of years. The interiors of the terrestrial planets are differentiated, meaning the material is segregated in layers according to density. Internal heat is responsible for differentiation: as interior of forming planet heats up, the rock and metal can melt, denser material will sink towards the center, less dense material will end up near or on the surface. Heat inside any world must flow to the surface: the heat get out through a process called convection, the interior of the earth is hot enough for bubbles of almost solid rock to expand and rise slowly. Thus, convection operates inside the earth: each terrestrial planet has a lithosphere, or ridged outer layer of cooler, lower density rock that floats on warmer, more plastic material below.
