This webpage belongs to, which is a website promoting [Jan Zuidhoek (2019) Reconstructing Metonic 19-year Lunar Cycles (on the basis of NASA’s Six Millennium Catalog of Phases of the Moon): Zwolle], and shows a concise curriculum vitae of the author of this ioneering book, which is available via this website.



Concise Curriculum Vitae


 Jan Zuidhoek was born in 1938, studied mathematics, physics, and astronomy at the university of Utrecht from 1960 to 1969, and was a teacher of mathematics from 1970 to 2001 at the Gymnasium Celeanum in Zwolle. After having gone deeply into the fields of history of mathematics, chronology, and history of early Christianity, he became fascinated by the Alexandrian computus, i.e. the Alexandrian form of the computus paschalis being the science developed from the beginning of the third century on behalf of the determination of the date of Paschal Sunday. In 2009 he succeeded, by using NASA’s Six Millennium Catalog of Phases of the Moon, in determining the initial year (AD 271) of De ratione paschali, i.e. the medieval Latin text containing the legendary 19-year Paschal cycle of Anatolius, the famous third century Alexandrian computist who invented the very first Metonic 19‑year lunar cycle. The underlying reconstruction of the so called proto-Alexandrian 19‑year lunar cycle was the subject of the presentation he gave at the international conference on the science of computus which took place at the university of Galway in 2010. This presentation resulted in his article entitled “The initial year of De ratione paschali and the relevance of its paschal dates”, which was published in 2017 in the proceedings of that conference. The presentation he gave at a similar conference in 2018 led to this book, in which he describes not only his reconstruction of both lost Alexandrian Metonic 19-year lunar cycles actively constructed already before the first council of Nicaea (AD 325), turning point in the history of Christianity, but also the development from the second of them to the particular Metonic 19-year lunar cycle from which thirteen centuries later the Italian astronomer Luigi Lilio and subsequently the German mathematician Christoph Clavius would develop a modern, astronomically more correct, system for determining the Gregorian calendar date of Easter Sunday.



some more photographs



back to homepage

© Jan Zuidhoek 2019-2021