KEPLER, JOHANNES. 1571-1630.
Astronomia nova ΑΙΤΙΟΛΟΓΗΖΟΣ, seu Physica Coelestis, tradita commentariis De Motibus Stellæ Martis, Ex observationibus G.V. Tychonis Brahe.... [Heidelberg: E. Vogelin], 1609.
Folio (386 x 252 mm). 2*-4*6 A-2E6 [χ]2. [xxxvi], 336,  pp, plus folding letterpress synoptic table. Approximately 300 woodcut diagrams in text, woodcut chapter initials, head-and tail-pieces. Period vellum over boards, title in manuscript to spine. Lacking 6 blanks, title and last leaf supplied in facsimile, without the engraved portrait of the dedicatee found in some copies. Numerous paper repairs and some edge-tears, toned, recased with hinges tissue-reinforced, upper cover with vellum repair, two smaller areas of loss to vellum, edges rubbed.
FIRST EDITION ONE OF THE FOUNDATIONAL TEXTS OF MODERN ASTRONOMY, KEPLER'S MOST IMPORTANT BOOK. Kepler sets forth the first two of his three laws of planetary motion, the Law of Ellipses, which shows that the orbits of the planets are elliptical rather than the perfect spheres imagined by Aristotle, and the Law of Equal Areas, which says that a line that connects the Sun and a planet will sweep out equal areas in equal times, meaning that a planet's orbital speed changes with its distance to the sun. The importance of these laws to modern astronomy can not be understated with them Kepler paved the way for his intellectual successors, including Galileo and Newton. "Copernicus had shown the sun to be the centre of the universe round which the earth and planets revolve, but his description of their movements was still strongly influenced by ancient conceptions of order and harmony. It was Kepler's aim to determine the true movements of the planets and the mathematical and physical laws controlling them" (PMM). "Copernicus had referred planetary motions to the center of the earth's orbit, but Kepler referred them to the sun itself, therefore paving the way for a real center of force and making possible the Newtonian celestial mechanics" (Dibner Heralds of Science 9). Caspar Bibiotheca Kepleriana 31; Grolier/Horblit 57; Houzeau & Lancaster Astronomie 11830; Lalande 149; Norman 1206; PMM 112; Zinner E. Geschichte und Bib. der Astronomischen Lit 4237.