1564-1617

German astronomer who was the first to discover a variable star. In 1596 Fabricus observed a third magnitude star in the constellation Cetus. He assumed it was a nova since it later disappeared. Johann Bayer observed the star again (1603) and named it Omicron. Johannes Holwerda discovered Omicron Ceti's variability in 1638 and named it Mira (miraculous) Ceti. Fabricus's observations of Mars, together with Tycho Brahe's, were used by Johannes Kepler to derive the laws of planetary motion.