German astronomer and priest Johannes Stoeffler was born Dec. 10, 1452. After completing his studies at the University of Ingolstadt, he settled at a parish in Justingen. Stoffler became well known as a maker of astronomical instruments, globes, and celestial clocks; his 1513 treatise on the astrolabe, Elucidatio fabricae ususque astrolabii, was the authority on the subject for decades. He also was a celebrated author of ephemerides – reference books with the positions of astronomical objects organized in tables.
Stoeffler went on to receive the chair of mathematics and astronomy at the University of Tubingen, and spent a good portion of his career working and writing on calendar reform at the invitation of the Catholic Church. (Though the Church disregarded his suggestion that astronomers be responsible for determining the date of Easter each year.) He died of the plague in 1531.
