maculis solarib stellis circa iouem (1 Ergebnisse)

First edition. First edition, rare, of Scheiner's second series of letters on sunspots and the satellites of Jupiter. This is one of the first books containing telescopic observations and illustrations, and is a fundamental text for the history of the telescope and Galilean studies. "[Scheiner (1573-1650)] was appointed professor of Hebrew and mathematics at Ingolstadt in 1610. The following year Scheiner constructed a telescope with which he began to make astronomical observations, and in March 1611 he detected the presence of spots on the sun. His religious superiors did not wish him to publish under his own name, lest he be mistaken and bring discredit on the Society of Jesus; but he communicated his discovery to his friend Marc Welser in Augsburg. In 1612 Welser had Scheiner's letters printed under the title Tres epistolae de maculis solaribus, and he sent copies abroad, notably to Galileo and Kepler. Scheiner believed the spots were small planets circling the sun; and in a second series of letters, which Weiser published in the same year as De maculis solaribus . accuratior disquisitio, Scheiner discussed the individual motion of the spots, their period of revolution, and the appearance of brighter patches or faculae on the surface of the sun. Having observed the lower conjunction of Venus with the sun, Scheiner concluded that Venus and Mercury revolve around the sun. Welser had concealed Scheiner's identity under the pseudonym of Appeles latens post tabulam. Galileo, however, identified Scheiner as a Jesuit and took him to task in three letters addressed to Welser and published in Rome in 1613 [Istoria e dimostrazioni intorno alle macchie solari]. Galileo claimed priority in the discovery of the sunspots and hinted darkly that Scheiner had been apprised of his achievement and was guilty of plagiarism" (DSB). Scheiner concluded that "A new world system was called for, one where Mercury and Venus, and perhaps other bodies, went around the Sun, and where the regions about the Sun and Jupiter, and probably Saturn as well, were filled with numerous planetary bodies" (Reeves & Van Helden, p. 181). Galileo's sunspot letters were published in two issues, one of which contains an appendix reprinting the two Scheiner works (but with illustrations inferior to the originals). OCLC lists, in the US: Cal Tech, Yale, Adler, Harvard, Johns Hopkins, Linda Hall, Duke, Cornell, and Rice. ABPC/RBH list six copies, all in modern bindings except the Macclesfield copy, which was part of a sammelband. The present work, 'On solar spots and the stars wandering around Jupiter; a more accurate enquiry' "began with a long and quite superfluous geometrical demonstration about internal and external angles of triangles. Scheiner then proceeded to use this demonstration in an exhaustive geometrical explanation of the conjunction of Venus of 11 December 1611, the timing of which he had misjudged [in Tres epistolae] in his use of Magini's Ephemerides Having thus shown himself to be a perfectly capable mathematician, and having reduced his error to an incidental oversight, Scheiner returned to the sunspots. As before, he presented his second series of observations, from 10 December 1611 to 12 January 1612, in a group of small diagrams in which the sizes of the spots were exaggerated He made a number of important points, alleging that the spots were rarely spherical, that they were almost constantly changing their shapes, that they appeared largest in the middle and narrowest near the limb, and that they could not usually be seen at the limb, but appeared and disappeared a little distance from it. He also noted that the spots split up, coalesced, and were often temporarily surrounded by groups of other very small spots, that such groupings were more compact near the limb, and rather loose near the center, and that they had rough edges, and were darker at their center and lighter at their borders. Some spots were darker near the limb than towards the center of the Sun's disc, they moved more slowly near the limb, and their motion appeared to be parallel to the ecliptic. "Scheiner illustrated these conclusions by a discussion of his observations of individual spots, in the course of which he offered a general assumption about the nature of the Sun. Focusing on the speed of those spots moving parallel to and at some distance from the ecliptic, he inferred that they could not be attached to the solar surface, which he assumed was hard and unchanging. If the Sun were a solid body and the spots adhered to its surface, one would expect that a spot at a more northerly solar latitude would take exactly as much time to travel its shorter route across the face of the Sun as a spot on the ecliptic. Because this did not happen, and because Scheiner believed the Sun to be a solid body, he concluded that the spots could not be on its surface. "The spots' constantly changing shapes reinforced this conclusion. Because the Sun was conventionally held to be a hard and unchanging globe, the ceaseless metamorphosis in the spots could be accommodated only beyond the solar body. The fact that the spots were darker near the limb than at the center appeared likewise to support this conclusion, for in the center of the Sun its most powerful perpendicular rays penetrated the material of the spots to some extent, and reached the eye. Such was not the case at the limb, as Scheiner demonstrated with a diagram similar to the one he had used in Tres epistolae to discuss the varying illumination of the spots. If the spots were on the surface in the form of chasms, they would necessarily appear darker near the center of the Sun and lighter near the limb. As Scheiner saw it, the spots were 'shadow-casting bodies [that] wander around the Sun.' "Scheiner went into great detail about the large spot ?, which he compared with the spot seen in 1607 by Kepler, who had supposed it to be Mercury, and depicted it in his Phenomenon singulare of 1609. Here his use of project.