BIO 200 Lecture Notes - Lecture 2: Protoplanetary Disk, Protoplanet, Archean

• School: University at Buffalo
• Department: Biological Sciences
• Course: BIO 200
• Professor: jessicapoulin

Document Summary

Perturbations in the outer rings of the disk -> protoplanets. Stars close to protoplanetary disk destroyed in supernova. Formation of the sun: protoplanets -> shockwave -> most mass concentrated in the middle. > enormous amount of heat -> nuclear fusion of hydrogens -> 2 hydrogen = helium -> formation of the sun. Formation of the earth: gravity condenses -> rest of protoplanetary areas -> ring -> large fragments collide -> destined to become planets -> protoplanet = earth. Earth: 4. 6 billion years ago (10-20 million years to form) Precambrien supereon: hadean, archean, proterozoic: hadeon eon: no oceans, no oxygen, planetoids + bombardment + residual heat -> fully molten (hydrogen, helium), no protective atmosphere. > as soon as atmosphere appears -> life appears. Life: unicellular life 3b years ago, fossils of stromatolites (cyanobacteria) (archean. Eon), bacteria and archaea represented as soon as we had life forms.