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General
Copernicus, Nicolaus (1473-1543)
Einstein, Albert (1879-1955)
Galileo Galilei (1564-1642)
Hipparchus (c. 180-125 BC)
Hubble, Edwin P. (1889-1953)
Jansky, Karl (1905-1950)
Kepler, Johannes (1571-1630)
Newton, Issac (1642-1727)
Ptolemy (2nd Century AD)
Hawking, Stephen (1942-1998+)

Harlow Shapley was an American astronomer who discovered the galactic distance scale using Cepheid Variables and observed nearby galaxies.

LINKS
Brief description of what Shapley did, including further links, and information on terms such as Cepheid Variables and RR Lyrae among others
http://www.treasure-troves.com/bios/Shapley.html

Shapley's determination of the size of the galaxy including diagrams
http://zebu.uoregon.edu/~soper/MilkyWay/shapley.html

An obituary of Harlow Shapley
http://antwrp.gsfc.nasa.gov/diamond_jubilee/1920/shapley_obit.html

A short biography of Harlow Shapley
http://www.phys-astro.sonoma.edu/BruceMedalists/Shapley

The great debate of 1920...Shapley - Curtis debate on scale of universe
http://antwrp.gsfc.nasa.gov/diamond_jubilee/debate20.html