Holwarda, Johannes Phocylides [Fokkens]

Born Holwarden, Friesland, the Netherlands, 19 February 1618

Died Franeker, Friesland, the Netherlands, 22 January 1651

Johannes Holwarda's most famous observational accomplishment was his rediscovery of the variable star Mira (o Ceti) in the constellation Cetus.

Holwarda studied in Franeker under Adrian Metius and graduated in 1640 with a doctoral degree in medicine. In 1639, he became a lecturer in logic and was promoted in 1647 to professor of philosophy in Franeker. In addition to philosophy, Holwarda studied theoretical and practical astronomy and worked as a medical practitioner.

In 1640, Holwarda wrote his Dissertatio astronomica, in which he examined in great detail the widely used astronomical tables of Philip Lansbergen . In this work and according to his own calculations and observations, Holwarda found errors and theoretical mistakes of a considerable magnitude. Holwarda proved to be a persistent