This webpage belongs to www.janzuidhoek.com, which is a website promoting [Jan Zuidhoek
(2021) Reconstructing Metonic 19-year Lunar Cycles
(on the basis of NASA’s Six Millennium Catalog of
Phases of the Moon): Zwolle], and concerns this groundbreaking
book, which is available via this website, and its author Jan Zuidhoek.
Book and Author
This book explains, by
following the mainstream of the history of the computus
paschalis developed from early in the third century
for the purpose of determining (Alexandrian or Julian calendar) dates of
Paschal Sunday which rose shortly after AD 250 in Alexandria (Egypt) to
ultimately (in AD 1582, turning point in the history of chronology) flow
into a modern way of determining (Gregorian calendar) dates of Easter, how of
old dates of Paschal Sunday depend on phases of the moon and how recently, on
the basis of NASA’s Six Millennium Catalog of Phases
of the Moon, both lost Metonic 19‑year lunar
cycles constructed in Alexandria before the first council of Nicaea in AD 325 (turning point in the history of
Christianity) were reconstructed.
The author of this
groundbreaking book 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, of chronology, and of
early Christianity, ultimately resulting in his lucid webpage “Christian Era and Universal Time”, he
became fascinated by the Alexandrian computus. In
2009 he succeeded, by using the Six Millennium Catalog,
in determining the Metonic 19‑year lunar cycle
underlying the fifth century Latin text De
ratione paschali
containing the legendary 19‑year Paschal cycle of the famous third
century Alexandrian computist Anatolius.
The presentations he gave at the international conferences on the science of computus at the university of Galway in 2010 and 2018
resulted in 2017 in an article entitled “The initial year of De ratione paschali and the
relevance of its paschal dates” and in 2019 in the first edition of this book
reducing that pioneering article to a preparatory study.
© Jan Zuidhoek 2019-2022