Chap 12.1 Astronomy

Chap 12.1 Astronomy - Josh Kelly 11/2/10 Astronomy Chapter...

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Josh Kelly 11/2/10 Astronomy Chapter 12.1 Radar ranging – We measure the Earth-Sun distance by bouncing radio waves off planets and using some geometry. Parallax – We measure the distances to nearby stars by observing how their positions change, relative to the background stars, as Earth orbits the Sun. These distances rely on our knowledge of the Earth-Sun distance, determined with radar ranging. Main sequence Fitting – We know that distance to the Hyades star cluster in the Milky Way Galaxy through parallax. Comparing the apparent brightness’s of its main sequence stars to those of main sequence stars in other clusters gives us the distances to other star clusters in our galaxy. Cepheid Variables – By studying Cepheids in star clusters with distances measured by main sequence fitting, we learn the precise period-luminosity relation for Cepheids. When we find a Cepheid in a more distant star cluster or galaxy, we can determine its luminosity by measuring the period between its peaks in brightness and then use this
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This note was uploaded on 01/25/2012 for the course 750 110 taught by Professor Ericgawaiser during the Fall '10 term at Rutgers.

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Chap 12.1 Astronomy - Josh Kelly 11/2/10 Astronomy Chapter...

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