GSC 102 Midterm: gsc 102 exam 2 study guide
12 Dec 2017
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Lightyears the distance that light can travel in one year. (1 lightyear = 5,900,000,000,000 miles) Parallax to determine the distance to (relatively) nearby objects. A parsec is the distance to an object whose parallax angle is 1 arcsecond when using a 1 au baseline. There are plenty of fuzzy, gassy, diffuse nebulae in the galaxy. Cepheid stars pulse with a frequency which is proportional to their luminosity. Doppler effect is when a wave emitted or received by a moving object appears to change. Light from things moving towards us gets bluer, and from things moving away from us gets redder. It turns out that all very distant galaxies are redshifted. Hubble"s law observes that more distant galaxies are moving away from us more quickly. Expansion of the universe and age of the universe. Hubble"s law implies that space is expanding. We can extrapolate this expansion backwards to get an age for the universe: 13. 7 billion years.
