Christoph Clavius Biography

Christoph Clavius

Christoph Clavius was born in Bamberg, Bavaria on March 25, 1538 and died on February 2, 1612 in Rome, Italy. His life’s work was devoted to practicing mathematics and astronomy. It is suspected that he changed his name from a German name, possibly 'Schlüssel', which means ‘key’, to the Latin name ‘Clavius’ which also means ‘key’. Clavius was a member of the Jesuit Order, where he received his education and was sent to University of Coimbra in Portugal in 1556. He became a Professor of Mathematics at Collegio Romano in 1565, while still a student of theology. He published several books, the most well known one being The Elements of Euclid.

Gregorian Calendar

Although his primary studies were in the field of mathematics, his observation of the solar eclipse in 1560 inspired him to pursue the study of astronomy. His first and most significant astronomical achievement was his reformation of the Julian calendar (which came to be known as the Gregorian calendar under King Gregory XIII) and the establishment of functioning leap years. Since the Gregorian calendar used a more accurate value for the tropical year than the Julian calendar used, Clavius used its concept of omitting centennial years to correct the calendar, which became known as the solar correction. He proposed the rule that leap years occur in years that are divisible by four, except years ending in ‘00’ must be divisible by 400. We still use this rule today. Clavius met with Galileo in Rome in 1587, and the two occasionally corresponded from that day onward. Clavius confirmed Galileo’s discoveries, however, he did not confirm Galileo’s theory. As an astronomer, Clavius supported the Ptolemaic system and strongly opposed Copernicus. His development of the modern calendar is extremely significant, although it is greatly overlooked today.