On August 13, 1596, Frisian theologian and astronomer David Fabricius observed the first known periodic variable star, which he called Mira Ceti (The ‘Wonder’ in the stellar constellation ‘Whale’).
David Fabricius – Early Years
David Fabricius was born in Esens, East Frisia, the son of a blacksmith. Not much is known about his childhood and youth. He attended the Latin schools in Norden and probably in Braunschweig. He later once remarked that his teacher Heinrich Lampadius († 1583) in Braunschweig had introduced him to astronomy and mathematics. After finishing school he studied, probably at University of Helmstedt. After a short period of study he took up office as a Protestant pastor in Resterhafe near Dornum at the age of 20. As was common for Protestant ministers of the day, he dabbled in science: his particular interest was astronomy. Thus, in the following years, he spent a lot time studying the heavens and the stars. Since 1590 he recorded his daily weather observations, exchanged letters on astronomical questions with the astronomer Justus Byrg from Cassel in 1593 and 94, and fabricated himself the most necessary astronomical instruments, as e.g. quadrants, semisextants etc.
Fabricius also started communicating with contemporary scientists about the movements of planets, about northern lights as well as comets. Amongst them were Tycho Brahe, Johannes Kepler, and Simon Marius. Between 1601 and 1609 he exchanged forty letters with Kepler, mainly about the planet Mars. He undertook numerous journeys and became acquainted with important contemporaries. When Tycho Brahe was staying in Wandsbek from 1597 to 1599, David Fabricius was one of his visitors.
The Discovery of Mira Ceti
On August 13, 1596 (Gregorian calendar), Fabricius with the help of a telescope noticed the alterability of the star Omikron at Cetus. This star changes about every 331 days its luminosity. Due to this weird ability, Fabricius named this star ‘res mira‘ (strange thing). Hoiwever, since Johannes Hevelius  it is simply called Mira, the “Wondrous”. Cetus is a very large but often hard to notice constellation between Fish and the Eridanus. It contains next to Mira another variable star, Tau Ceti. Mira became the eponym of a whole class of long-period variable stars. David Fabricius’ discovery was very important to contemporary scientists. Many believed that the constellations of the zodiac were unalterable and eternal, which he disproved.
Focussing on Meteorology
After his amazing success, Fabricius began focusing on meteorology, researching the influence of celestial bodies on the air circulation on earth. His manuscripts on the topic were well preserved and exist up to this day. In his last period, David Fabricius worked together with his son, Johann. In 1611 his son Johann (the eldest of seven sons) returned from his studies in Leiden and brought a telescope with him. Observing the sun in February 1611, he noticed dark spots. Father and son Fabricius made joint observations and were able to establish their existence without any doubt. David Fabricius determined the rotation time of the sun from the movement of the spots on the visible solar disk. Although Galileo Galilei in Pisa and Thomas Harriot in London had already noticed spots on the sun in 1610, Johann Fabricius and Christoph Scheiner in Ingolstadt were the first to write and publish a scientific treatise on the subject.
Further Projects and Mysterious End
In addition to astronomy, Fabricius also investigated a possible influence of the stars on the movements of the Earth’s air circuit. In 1589 he produced the first East Frisian map printed in East Frisia under the title “Never and warhafftige Beschriinge des Ostfreslandes“. David Fabricius’ ending is a bit strange and mysterious. He is said to have delivered a sermon shortly before his death in which he claimed he knew a goose and chicken thief, but did not want to reveal his name. A self-made horoscope predicted disaster for May 7, 1617 and Fabricius spent the day in his house. In the evening he thought the danger was over and set out for a walk. On the way, a farmer, Frerik Hoyer, killed him with a peat spade. Hoyer obviously felt embarrassed as a thief and was angry about it. He was whacked to death for what he did.
Caroline Crawford, The Life of Stars 
References and Further Reading:
-  Fabricius at The Biographical Encyclopedia of Astronomers [PDF]
-  Fabricius at the Galileo Project
-  David Fabricius at Wikidata
-  Tycho Brahe – The Man with the Golden Nose, SciHi Blog
-  And Kepler Has His Own Opera – Kepler’s 3rd Planetary Law, SciHi Blog
-  Johannes Hevelius and his Selenographia, SciHi Blog
-  Johannes Fabricius and the Sunspots, SciHi Blog
-  Timeline of 16th century astronomers, via Wikidata
-  Simon Marius and his Astronomical Discoveries, SciHi Blog
-  Johannes Holtmanns: Fabricius, David. In: Allgemeine Deutsche Biographie (ADB). Band 6, Duncker & Humblot, Leipzig 1877, S. 505 f.
-  Works by or about David Fabricius at German Digital Library (DDB)
-  Caroline Crawford, The Life of Stars, Gresham College at youtube