Christopher Clavius, (March 25, 1538 – February 12, 1612) was a German Jesuit mathematician and astronomer who was the main architect of the modern Gregorian calendar. In his last years he was probably the most respected astronomer in Europe and his textbooks were used for astronomical education for over fifty years in Europe and even in more remote lands (on account of being used by missionaries). Image File history File links Download high resolution version (972x1406, 1337 KB) Christopher Clavius (1538–1612), German mathematician and astronomer. ... March 25 is the 84th day of the year in the Gregorian calendar (85th in leap years). ... Events Treaty of Nagyvarad. ... February 12 is the 43rd day of the year in the Gregorian Calendar. ... Events January 20 - Mathias becomes Holy Roman Emperor. ... The Society of Jesus (Latin: Societas Iesu), commonly known as the Jesuits, is a Roman Catholic religious order. ... A mathematician is a person whose primary area of study and research is mathematics. ... An astronomer or astrophysicist is a scientist whose area of research is astronomy or astrophysics. ... Inscription on the tomb of Pope Gregory XIII celebrating the introduction of the Gregorian Calendar The Gregorian calendar is the calendar that is used nearly everywhere in the world. ... Europe is conventionally considered one of the seven continents of Earth which, in this case, is more a cultural and political distinction than a physiographic one, leading to some dispute as to Europes actual borders. ... A missionary is a propagator of religion, often an evangelist or other representative of a religious community who works among those outside of that community. ...

Very little is known about Clavius' early life other than the fact that he was born in Bamberg in either 1538 or 1537 (the exact year is somewhat unknown and depends on when one assumes a new year begins). His given name is not known to any great degree of certainty — it is thought by scholars to be perhaps Christoph Clau or Klau. There are also some who think that his taken name, "Clavius", may be a pun on his original German name, suggesting that his name may have been "Schlüssel" (German for "key", which is "clavis" in Latin). Bamberg is a town in Bavaria, Germany. ... The New Year is an event that happens when a culture celebrates the end of one year(like end of 2005,come 2006)) and the beginning of the next. ...

Clavius joined the Jesuit order in 1555. He attended the University of Coimbra in Portugal, where it is possible that he had some kind of contact with the famous mathematician Pedro Nunes . Following this he went to Italy and studied theology at the Jesuit Collegio Romano in Rome. In 1579 he was assigned to compute the basis for a reformed calendar that would stop the slow process in which the Church's holidays were drifting relative to the seasons of the year. This calendar was adopted in 1582 in Catholic countries by order of Pope Gregory XIII and is now used worldwide. The Society of Jesus (Latin: Societas Iesu), commonly known as the Jesuits, is a Roman Catholic religious order. ... Events Russia breaks 60 year old truce with Sweden by attacking Finland February 2 - Diet of Augsburg begins February 4 - John Rogers becomes first Protestant martyr in England February 9 - Bishop of Gloucester John Hooper is burned at the stake May 23 - Paul IV becomes Pope. ... The University of Coimbra (Portuguese: Universidade de Coimbra) is a Portuguese public university in Coimbra, Portugal. ... Pedro Nunes (latin, Petrus Nonius), (1502, Alcácer do Sal – August 11, 1578, Coimbra) was a Portuguese mathematician, born from a New Christian (of Jewish origin) family. ... The North American College at the Gregorian The Pontifical Gregorian University is a Roman Catholic theological seminary in Rome. ... For other uses, see Rome (disambiguation). ... Events January 6 - The Union of Atrecht united the southern Netherlands under the Duke of Parma, governor in the name of king Philip II of Spain. ... Events January 15 - Russia cedes Livonia and Estonia to Poland February 24 - Pope Gregory XIII implements the Gregorian Calendar. ... Gregory XIII, born Ugo Boncompagni (January 7, 1502 – April 10, 1585) was pope from 1572 to 1585. ...

Within the Jesuit order, Clavius was almost single-handedly responsible for the adoption of a rigorous mathematics curricula in an age where mathematics was often ridiculed by philosophers and theologians.

As an astronomer Clavius held strictly to the geocentric model of the solar system, in which all the heavens rotate about the Earth. Though he opposed the heliocentric model of Copernicus, he recognized problems with the orthodox model. He was treated with great respect by Galileo, who visited him in 1611 and discussed the new observations being made with the telescope; Clavius had by that time accepted the new discoveries as genuine, though he retained doubts about the reality of the mountains on the Moon. In light of this fact, it is very ironic that a large crater on the moon is named for him. This artistic representation of the geocentric model shows signs of the zodiac and the solar system with world at centre. ... Earth is the third planet in the Solar system. ... Heliocentric Solar System In astronomy, heliocentrism is the theory that the Sun is at the center of the Universe and/or the Solar System. ... Nicolaus Copernicus (February 19, 1473 – May 24, 1543) was an astronomer who provided the first modern formulation of a heliocentric (sun-centered) theory of the solar system in his epochal book, De revolutionibus orbium coelestium. ... Galileo Galilei. ... Events June 23 - Henry Hudsons crew maroons him, his son and 7 others in a boat November 1 - At Whitehall Palace in London, William Shakespeares romantic comedy The Tempest is presented for the first time. ... 50 cm refracting telescope at Nice Observatory. ... Bulk composition of the moons mantle and crust estimated, weight percent Oxygen 42. ... To meet Wikipedias quality standards, this article may require cleanup. ... Clavius on the moon Clavius is one of the largest crater formations on the Moon, and it is the third largest crater on the visible near side. ...

References

• James M. Lattis, Between Copernicus and Galileo: Christoph Clavius and the collapse of Ptolemaic cosmology (University of Chicago Press, 1994).

External links

• The Galileo Project — biography of Christopher Clavius.
• Opera Mathematica — the complete mathematical works of Christopher Clavius.
• John J. O'Connor and Edmund F. Robertson. Christopher Clavius at the MacTutor History of Mathematics archive.