Nicolaus Copernicus Prussia also resisted the Polish crown's efforts for greater control over the region. "Encyclopædia Britannica", "Encyclopedia Americana", "The Concise Columbia Encyclopedia", "The Oxford World Encyclopedia", and "World Book Encyclopedia" refer to Copernicus as a "Polish astronomer". Sheila Rabin, writing in the "Stanford Encyclopedia of Philosophy", describes Copernicus as a "child of a German family [who] was a subject of the Polish crown", while Manfred Weissenbacher writes that Copernicus's father was a Germanized Pole. There are additional arguments for Kopernik's Polish descent on his father's side. Kopernik's Y-DNA haplogroup, R1b L51, is found in southern Poland (in Silesia, where his father
Nicolaus Copernicus several Kraków astronomers with whom he collaborated in 1515–30 in observing eclipses. Tycho Brahe would include a fragment from the "Commentariolus" in his own treatise, "Astronomiae instauratae progymnasmata", published in Prague in 1602, based on a manuscript that he had received from the Bohemian physician and astronomer Tadeáš Hájek, a friend of Rheticus. The "Commentariolus" would appear complete in print for the first time only in 1878. In 1510 or 1512 Copernicus moved to Frombork, a town to the northwest at the Vistula Lagoon on the Baltic Sea coast. There, in April 1512, he participated in the election of Fabian