PHYS 1201 Study Guide - Midterm Guide: Virgo Supercluster, List Of Largest Galaxies, Galactic Center
Document Summary
Solar system consists of the sun & all the objects that orbit it. Galaxy: great island of stars in space; from a few hundred million to a trillion or more stars. Milky way galaxy (ours) disk-shaped collection of stars, more than. 100 billion stars, one of 2 largest galaxies in the local group. Galaxy clusters: groups of galaxies with more than a few dozen members. Universe: sum total of all matter & energy. Earth solar system milky way galaxy local group galactic. *expanding universe: average distances between galaxies are increasing with time. Gravity began to draw matter together; galaxies etc. happen when gravity wins out against the overall expansion. A star is born when gravity compresses the material in a cloud to the point where the center becomes dense & hot enough to generate nuclear fusion. Nuclear fusion: lightweight atomic nuclei smash together and stick to make heavier nuclei. nuclear fusion.
