On 3rd of August 1596 the amateur Frisian astronomer David Fabricius first observed the variable star Mira. There is some evidence that Mira might have been observed by earlier astronomers but it was Fabricius’ observation that eventual led to Mira being recognised as the first variable star.
Fabricius, whose real name would have probably been Schmidt, was a village pastor in East Frisian and serves as model for hundreds of similar clerics throughout Europe who in the 17th, 18th and 19th centuries contributed significantly to the development of, above all, natural history as devoted amateurs who invested their spare time in the study of nature. He made his first appearance on the European astronomy scene in 1592 when he wrote to Jost Bürgi, mathematicus and instrument maker at the court of Wilhelm IV of Hessen-Kassel, then the second most important centre for astronomy in Europe, requesting assistance in the construction of astronomical instruments. When he first observed Mira in 1596 he wrote a letter describing his discovery, he thought it was a nova, to Tycho Brahe in Hven the leading centre for astronomical research in Europe. Brahe was very impressed by the work of the Frisian cleric and an important scientific correspondence developed between the two men that lasted until Brahe’s death in 1601. On several occasions Brahe tried to convince Fabricius to come and work with him but the pastor preferred to remain in East Frisian. In 1601 Fabricius visited Tycho in Prague and during his stay he met Simon Marius with whom he also conducted an astronomical correspondence.
He did not however meet Brahe’s newest assistant Johannes Kepler who was in Austria dealing with family business during Fabricius’ visit, however a lively correspondence developed between the Frisian Pastor and the Imperial Mathematicus which lasted more than eight years with some of the letters running to 40 or 50 pages. This correspondence is very important for the history of astronomy because it is in these letters that Kepler outlines his path towards his first two planetary laws. Fabricius proved a worthy partner in this endeavour criticising and pointing out the weak points in Kepler’s argumentation. Criticism that Kepler was more than willing to accept from the man whom he regarded as the best observational astronomer in Europe after the death of Tycho. However Fabricius never accepted Kepler’s elliptical heliocentric orbits remaining a loyal Tychonicer, a fact that may have led to Kepler breaking off the correspondence somewhat abruptly in 1609.
In 1611 Fabricius’ son Johannes brought home a telescope from the University of Leiden where he was studying medicine. With this instrument the father and son, with the son this time in the leading role, discovered the sunspots. Although they were not the first European astronomers to make this discovery, this honour goes to Thomas Harriot, Johannes Fabricius was the first to publish it in his De Maculis in Sole in 1611. Unfortunately his publication went largely unnoticed and is not mentioned at all by Galileo and Christoph Scheiner in their monumental argument as to who first discovered the sunspots.
The end of David Fabricius’ life reads like something concocted by a Hollywood scriptwriter. Shortly before his death the worthy pastor held a sermon in which he claimed to know the identity of a chicken and goose thief but he did not reveal the name of the delinquent. On the 7 May 1617 he was beaten to death with a spade by the farmer, Frerik Hoyer, who thought that it was he who had been denounced from the pulpit.
David Fabricius is one of many scientific investigators who made significant contributions to the development of science but who remain largely unknown in our culture of big names and spectacular events.