PCS 181 Lecture Notes - Lecture 4: Maltese Lira, Elliptical Galaxy, Spiral Galaxy
31 Jan 2017
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Document Summary
You get clumps of dark matter, and they have enough gravity to pull dark and regular matter together, which fall in and become galaxies. Andromeda- biggest galaxy (2-3x as big as the milky way) Our galaxy has a bright bulb in the centre, a disk and spiral arms, a halo (cloud of extra stars that milky way lives in). In terms of scale, our galaxy is about 100, 000 light years across and a thousand light years thick. The milky way has about 170 globular clusters. Globular cluster m80- 12 billion years old: one of the first things to be born in the universe as the universe is about 13 billion years old. Hundreds of thousands upto millions of stars. 60 to 150 light years across in the core, stars closer than size of the solar system, which means that collisions are possible. It is possible to have planets around globular clusters, they have been found.
