AY 101 Lecture Notes - Lecture 13: Terrestrial Planet, Volcanism, Red Color
Document Summary
Red color due to iron oxide dust. Seasonal variations like earth with expanding and shrinking polar caps. Water is present, mainly in the forms of ice and vapor. Nasa has suggested that early in its history, the planet had a thicker atmosphere and a substantial ocean of liquid water. Over time, solar heat boiled off the air, causing much of the water to be lost in space. There is controversial evidence for fossil microbial life. Distance from sun (farther from sun = less heat) Bigger, more massive terrestrial planet = more geologically active. Bigger, more massive = higher surface gravity. Size, mass, and distance from sun combine to determine the ability of a world to hold and retain an atmosphere. Mercury and titan are similar-sized worlds, 1/3 earth size. The moon is too small to have held its internal heat for long and is basically geologically dead.
