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Astrolabe.org: The Astrolabe
A description of the ancient astrolabes and how they worked. Provides information about definitions, collections, and also includes photos.
Curated OER
Educational Technology Clearinghouse: Clip Art Etc: Nicolaus Copernicus
Nicolaus Copernicus (February 19, 1473 - May 24, 1543) was the first astronomer to formulate a scientifically based heliocentric cosmology that displaced the Earth from the center of the universe. His epochal book, De revolutionibus...