4.13 Christoph scheiner

Christoph Scheiner was born in Wald, near Mindelheim in Swabia (southwest Germany), on 25 July 1573. Heattended the Jesuit Latin school in Augsburg, continued his studies in the Jesuit college atLandsberg, and entered the Jesuit order in 1595. Having completed his preparatory study, he entered the university at Ingolstadt in1600. Here he studied metaphysics and devoted himself to the study of mathematics. In 1610 he joined the faculty of the Jesuitcollege of the university as professor of Mathematics and Hebrew.

Scheiner's talents lay in the mathematical sciences and instruments. Early in his career hebecame an expert on the mathematics of sundials and also invented a pantograph (a device for copying and enlarging drawings). Uponhearing about Galileo's discoveries with the telescope, in 1610, Scheiner immediately set out to obtain good telescopes with whichto scrutinize the heavens. After verifying Galileo's discoveries for himself, he turned his attention to the Sun, where, in Marchor April 1611, he discovered sunspots . He was neither the first to observe sunspots nor the first to publish on the subject, but hispublication was the start of a controversy with Galileo over the nature of sunspots.

Because of the conservative stand of the Jesuit order on cosmological issues, Scheiner attempted to rescuethe perfection of the Sun, and by implication the heavens generally, from imperfection. He therefore postulated thatsunspots were caused by satellites of the Sun whose shadows are projected on to Sun's disk as they cross in front of it. Histract, Tres Epistolae de Maculis Solaribus ("Three Letters on Solar Spots") appeared in Augsburg early in 1612, underthe pseudonym "Apelles latens post tabulam," or "Apelles hiding behind the painting." These letters were written to Marc Welser , an Augsburg banker and scholar who was a friend and patron to Jesuit scholars.

Welser invited Galileo to comment on these letters, and Galileo responded with two letters to Welser of hisown in which he argued that sunspots are on or near the surface of the Sun, that they change their shapes, that they are often seento originate on the solar disk and perish there, and that therefore the Sun is not perfect. In the meantime, Scheiner hadwritten two further letters to Welser on this subject, and after reading Galileo's first letter he wrote yet another. This secondseries of three letters was published by Welser in the fall of 1612, with the title De Maculis Solaribus et Stellis circa Iovis Errantibus Accuratior Disquisition ("A More Accurate Disquisition Concerning Solar Spots and Stars [i.e., Satellites]Wandering around Jupiter"). Again, Scheiner used the pseudonym of Apelles. Scheiner restated his argument that sunspots were causedby satellites and argued that Jupiter had more satellites than the four discovered by Galileo. Upon reading this tract, Galileo wroteyet a third sunspot letter to Welser, dated December 1612, and in 1613 the Lyncean Academy published all three letters under the title Istoria e Dimostrazioni intorno alle Macchie Solari e loro Accidenti ("History and Demonstrations Concerning Sunspots and their Properties.") A thirdof the copies contained reprints of Scheiner's two tracts. Although he was polite to Scheiner, Galileo refuted hisarguments and there was little doubt as to who was the winner of this dispute.

Scheiner went on to publish books on atmospheric refraction and the optics of the eye, and inthese works he built on the optical achievements of Johannes Kepler , thus providing important material for later writers on the subject. He also continued hisresearch on sunspots. In the meantime, he had begun instructing Arch Duke Maximilian, brother of Emperor Rudolph II, in themathematical subjects, and in 1616 he left Ingolstadt for good to become Maximilain's advisor. Scheiner henceforth had the patronageof the Emperor's brother and in 1621 he became the confessor of Arch Duke Karl, brother of the new Emperor, Ferdinand II. One ofScheiner's greatest achievements was the foundation of a new Jesuit college in Neisse in Silesia. When the Arch Duke died on avoyage to Spain in 1624, Scheiner went to Rome, where he stayed for the next eight years. It was in Rome that he published hisgreatest work, Rosa Ursina (1630), the standard work on sunspots for more than a century.

In his Assayer of 1623, Galileo had made certain disparaging remarks about those who had tried to steal hispriority of discovery of celestial phenomena. Although Galileo almost certainly had others in mind, Scheiner interpreted theseremarks as being directed against him. He therefore devoted the first book of Rosa Ursina to an all out attack on Galileo, and it has been said that his enmity toward Galileo wasinstrumental in starting the process against the Florentine in 1633. Scheiner's diatribe against Galileo does, however, not takeaway from the importance of Rosa Ursina . Here Scheiner agreed with Galileo that sunspots are on the Sun'ssurface or in its atmosphere, that they are often generated and perish there, and that the Sun is therefore not perfect. Scheinerfurther advocated a fluid heavens (against the Aristotelian solid spheres), and he pioneered new ways of representing the motions ofspots across the Sun's face. Because shortly after the appearance of Rosa Ursina sunspot activity decreased drastically (the so-called Maunder Minimum, ca. 1645-1710), his work was notsuperseded until well into the eighteenth century.

In 1633 Scheiner returned to the German region, where he spent the rest of his life in Vienna and Neisse, supervisingthe building of the Jesuit college. Until the end, he worked on a massive refutation of the Copernican theory , the finished part of which was published posthumously, in 1650, under the title Prodromus pro Sole Mobili et Terra Stabili contra Galilaeum a Galileis ("Introductory Treatise in Favor of a Moving Sun and a Stable Earth against Galileo Galilei"). The work remained virtuallyunkown and had no effect on the outcome of the debate between Copernicans and advocates of the geocentric/geostaticcosmology.