AST 346 Lecture Notes - Lecture 1: Milky Way, Outer Space, Quasar
Document Summary
Lecture 2: brief history of galaxies (part i) What are galaxies: galaxies are the fundamental particles of cosmology. Galaxies trace space and time: galaxies are collections of stars, gas, dust, and dark matter. Galaxies are formed and evolve with time. How we learn about galaxies: observations of the milky way galaxy. Composition of stars, gas, and dust: observations of nearby galaxies. Structure, kinematics, and composition of stars, gas, and dust. Large-scale structure: observations of distant, early, high-redshift galaxies, observations of quasar absorption lines. Gas and dust content of distant, early, high-redshift galaxies. Some notable early observations: 1610: galileo resolved the milky way into individual stars using his telescope, 1755: immanuel kant published general natural history and theory of the the heav- ens. Demonstrated how planar structure of the solar system arises from attractive force of gravity from the sun, which binds the system, and how orbits of the planets prevent its collapse.