ASTR 1P02 Lecture Notes - Coma Cluster, Barred Spiral Galaxy, Density Wave Theory
12 Mar 2013
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Document Summary
A diffuse band of light across the sky. Greeks called it galaxies kuklos (milky circle) Romans called it via lacte (milky way) Galileo used his telescope in 1609 to find that it consists of many faint (because they are very distant) stars. In the 18th century thomas wright and immanuel kant proposed that we observe this band of light because we live in a disk of stars. Size of the milky way and our location in it: After wwi harlow shaply measured our distance from globular clusters (clusters of 100,000 to 1,000,000 stars) He noticed that they are located on one side of the sky near the constellation of sagittarius. Shapley assumed that they are distributed in a spherical manner around the center of our galaxy. By measuring the distances to them he could deduce how far away we are from the center. Using similar method the astronomers have determined the size and the shape of the milky way.
