Lecture 21

Lecture 21 - 1. Determining the Scale of the Universe o...

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1. Determining the Scale of the Universe o Geometric methods Most reliable Best is annual paradox Can only measure a small part of the universe, only see so far Also distance to center of galaxy from stellar orbits around central black hole o Standard candles Most ways to get distance work this way Identify some type of objects with known luminosity Compare brightness to luminosity to get distance 2. Distance Determinations Near and Far o Low luminosity galaxies have less mass and thus rotate slower, and vice versa 3. The problem with a distance ladder: ladders wobble! 4. How big, and how old is the universe? o Hubble constant related the expansion (how fast its moving) of the universe to the distance o Hubble constant small? Not expanding fast, took a long time, very old o Hubble constant large? Universe expanding fast, quickly got to where we are today, very young 5. Elliptical Galaxies o Very different from spirals Some giant ellipticals much bigger than Milky Way
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This note was uploaded on 03/30/2012 for the course ASTR 1102 taught by Professor Staff during the Spring '08 term at LSU.

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Lecture 21 - 1. Determining the Scale of the Universe o...

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