Christoph Scheiner (1575–1650)

The Jesuit astronomer Christoph Scheiner was born on July 25, 1575. He joined the Jesuit order in 1595, and started his studies in 1601 at Ingolstadt where he later taught mathematics from 1610 to 1616.He moved to Innsbruck in 1616, was in Rome from 1624 to 1633, and died in Niesse on June 18, 1650. The above portrait is from the Stadt Müseum Ingolstadt.

Christoph Scheiner  image
Portrait of Christoph Scheiner (1575–1650).
Credit: Wikipedia.

The controversy between Scheiner and Galileo over priority in the discovery of sunspots was an important factor (though not the only one) responsible for the degradation in the relationship between Galileo and Roman members the Jesuit Order. By his own account Scheiner began observing sunspots in March or April 1611,together with his then assistant J.B. Cysat. The first published account of his observations are his "Three Letters on Sunspots" (Tres epistolae de maculis solaribus), dated November 11, 1611, addressed to Augsburg magistrate Mark Wesler (1558-1614) and published in Augsburg in January 1612. These were followed by three more letters in September 1612, again published via Wesler. Scheiner was required by his ecclesiastic superiors to write under the pseudonym "Appelles", to avoid possible embarrassment to the Jesuit order in the event that his findings were to prove spurious.

Scheiner's original opinion was that sunspots were small planets closely orbiting the Sun, a position convincingly refuted by Galileo in his own 1632 "Letters on Sunspots". Unlike Galileo, Scheiner pursued sunspot observations on a continuous basis for more than 15 years. In the course of doing so he devised techniques that greatly improved the accuracy of observed sunspot positions, and "designed specialized solar observing instruments". Results of his observations were published in 1630 in his "Rosa Ursina", a book four years in the making that opened with biting attack on Galileo, to which the latter was to reciprocate in his Dialogues.