Nicolaus Copernicus [Mikołaj Kopernik] (1473-1543)
Polish astronomer, mathematician, economist, and physician. In his principal work "De Revolutionibus Orbium Coelestium" ("On the Revolutions of the Celestial Orbs") which was published in 1543 (the year of his death), he presented a description of a heliocentric planetary system (in which the planets, including the Earth, revolve around the Sun). This was in opposition to the geocentric system (in which everything including the Sun and planets revolve around the Earth ), developed by the Alexandrian astronomer Ptolemy, and almost universally accepted for some fifteen hundred years before Copernicus.
Source:
http://www.uranos.eu.org/biogr/kopern.html Aleksander [Alex] Wolszczan (born 1946)
Contemporary Polish radioastronomer and astrophysicist, one of the foremost researchers of pulsars. Graduated from Nicolaus Copernicus University in Torun, Poland (1969), then earned a Ph.D. degree in physics there in 1975. His Ph.D. thesis concerned spectra of pulsars. Throughout his career he collaborated with Polish and American research centers. Since 1992 he lectured and conducted research on astronomy and astrophysics at Pennsylvania State University and lectured at Nicolaus Copernicus University in Torun, Poland.
Source:
http://www.uranos.eu.org/biogr/wolsz.html 
