Edwin Hubble 1889 1953 Biography American astronomer Education

Edwin Hubble (1889 - 1953) Biography • American astronomer • Education: University of Chicago • First to show other galaxy by photographing stars of Andromeda • Discovered the expansion of the Universe (Hubble Law) by observing the red-shifts of galaxies. Contributor: Mike Chu – Spring 2013, Montgomery College, Germantown http: //cosmology. carnegiescience. edu/timeline/1929 ? ? ?

1923 -24 Observations of Andromeda • The prevalent view of the time was that the Milky Way was the sole star system in an empty space • “Andromeda Nebula” was but a faint patch • Hubble photographed Andromeda and identified stars and Cepheid variables. • Hubble estimated the distance to be (? ? ) • (Comment: Add a picture) References: 1. Horizons by Michael Seeds, Chapter 12 ? ? ? 2. Wikipedia: ? ? ?

Hubble Expansion • Hubble worked at Mount Wilson Observatory (1919 -? ) • Vesto Slipher had already done some observations of galaxies (call “nebula” at the time? ) Showed that the recession velocity of galaxies is proportional to distance: v = H d where H is Hubble Constant Measured H=500 (km/s)/Mpc – 500 km/s for every Mpc Concluded that universe is expanding Over-estimated the value by 7 to 8 times (Comment: add original plot and a modern update)

Addendum (for students)

Follow-up topics (for mid- and long- presentation) • Early modern astronomy techniques, e. g. photographic plates • Early modern large ground-based telescopes, e. g. Mount Wilson Observatory (a documentary is available on PBS. org) • Prediction and history of Hubble Constant • The expansion of the universe