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 ASTRONOMY

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ASTRONOMY

of the heavens; the latter in that drawn from the twelve signs of the Zodiac.

Grasse, Lehrb. einer Literdrgesch. (Leipzig. 1839), II, con- tains a list of the earlier literature of the subject; Low, As- froloffi^ in der Bibel in Ben Chananja (1S63); Reitzenstein, Poimandrea (Leipzig, 1904); Maass, Die Tagesgiitter (Berlin, 1902); Chwolson, Ssabier und Ssabismus (1856); Kroll in Neite Jahrb. fur Phil, und Pad.. VII, 559, sqq.; Schiaparelli, L'astronomia neW Antico TeaUtrmmto (Milan, 1904); Boll, Spkara (Leipzig, 1905); Reitzenstein, Zwei religion&gesch. Fragen (Strasburg, 1901); Bousset, Religion des Judentums im neutestam. Zeitalter (Berlin, 1906). See also the literature quoted for ancient astrology. In discussing the "Star of the Wise Men ", spoken of in Matthew, use may be made (although caution should be observed) of the works of Felix von Oefele. Di^ A ngaben der Berliner _ Planetentafel P. 8279 verglichen mil der Geburtsgeschichte Christi. in Mitteilun^jen der Vorderasiat. Gesellach. (1903), VIII, Pt. II; Idem, Das Horoskop der Emp- iangnis Christi, in the .same proceedings, Pt. VI.

ZiMMERMANN, Die W Under der Planeten (Berlin, s. d.); JIayer, Handbuch der Astrologie (Berlin, 1891); Forster, Himmelskunde und Weisaagungen (Berlin. 1901); Mensing.\, Ueber tdle und neue Astrologie (Berlin, 1872); Lebrun, Hist, crit. des prat, superstit.: Maury, La magie ct Vaatrol. (Paris, 1857); KlESEWETTER, Gesch. des Okkultismus (Leipzig, 1895), II; Bocche-Leclercq, //is(. rfe ladivin. (Paris, 1879); Lenor- MANT, La divination chez les Chaldcena (Paris, 1875); Habler, Astral, im Altertum (Zwickau. 1881); Hommel, Aufadtze und Abhandlungen (Leipzig. 1892-1901); Winkler. Gesrh. Babi/lon und Asaj/r. (Leipzig. 1892); Id., Altorient. Forschungen (Leipzig, 1902), III, ii; Brug.sch, JEgyptologie; Jensen. Kosmologie (1893); Epping-Str.4SSMaier, Aatron. aua Alt-Babylon in Stimmen aus Maria-Loach, II; Boll, Sph(Fra (Leipzig, 1903); Bouche-Leclercq, L'aatrol. grecque (Paris, 1899); Kroll in AViM? Jahrbh. fiir Phil, und Pad., VII, 559; Dieterich, A.braxaa (Leipzig, 1904); Weber. Indien Studien, I; Reitzenstein, Potmarw^res (Leipzig. 1904); \}iiF.KlR,Religiovsgesch. Untersuch., I; Maass, Die Tagesgotier (Berlin, 1902); Steinschneider, Ilebr. UeberseU. (Berlin, 1893); Lowin, Ben Chnnanja (1863), 401: Burckhardt, Kultur der Renaissance (Leipzig. 1898), tr.; VolGT, Wiederbelebung des klaaa. Altertuma (Leipzig. 1898); collection of ancient astrological writings in Fabriciu.s. Bibl. gro'c (1790). Ill; Lilly, Christian Astrology Modestly Treated (London, 1647); Chrlstmas, Astrology, Cradle of the Twin Giants, Science and History (London, 1849); Schindler, Der Aberglaube des Mitteialters (Breslau, 1858); Star of Bethlehem, .see Searles in Catholic World, XLVII, 59.

Max Jacobi.

Astronomy (from Gr. fio-rpop, star; viixetv, to distrib- ute), a science of prehistoric antiquity, originat- ing in tlie elementary needs of mankind. It is divided into two main branches, distinguished as astrometrj' and astrophysics; the former concerned with determining the jilaces of the heavenly bodies, the latter, with the investigation of their chemical and physical nature. But the division is of quite recent date. The possibilities of antique science stopped short at fixing the apparent positions of objects on the sphere. Nor was any attempt made to rationalize the observed facts until the Greeks laboriously built up a speculative .system, which was finally displaced by the vast fabric of gravitational theory. Descriptive astronomy, meanwhile, took its rise from the invention of the telescope, and the facilities thus afforded for the close scrutiny of the denizens of the sky; while practical astronomy gained continually in refinement with the improve- ment of optical and mechanical arts. At the present time, astrophysics may be said to have absorbed descriptive astronomy, and astrometry necessarily includes practical research. But mathematical as- tronomy, grounded on the law of gravitation, keeps its place apart, though depending for the perfecting of its theories and the widening of its scope upon advances along the old, and explorations in new, directions.

Prehistoric Astronomy. — Fomial systems of astronomical knowledge were early estaolishetl by the Chinese, Indians. Egy~|>tians, and Babylonians. The Chinese were acquainted, probably in the third millennium B. c, with the cycle of nineteen years (rediscovered in 632 b. c. by Meton at Athens), by which, since it comprised just 235 lunations, the solar and lunar years were harmonized; they re- corded cometary apparitions, observed eclipses, and employed effective measuring apparatus. European methods were introduced at Pekin by Jesuit mis-

sionaries in the seventeenth century. Indian astron- omy contained few original elements. It assigned particular prominence to the lunar zodiac, called the nakshatras, or mansions of the moon, variously reckoned at twenty-seven or twenty-eight; and these, which were probably a loan from Chaldea, served mainly for superstitious purposes. In Egypt, on the other hand, considerable technical skill was attained, and a peculiar constellational system of obscure derivation, came into use. The Babylonians alone, among the nations of the fore-time, succeeded in laying the foundations of a progressive science. Through the medium of the Greeks, they transmitted to the West their entire scheme of uranography, our familiar constellations having been substantially designed on the plain of Shinar about 2800 B. c. Here, too, at a remote epoch, the "Saros" became known. This is a cycle of eighteen years and ten or eleven days, which affords the means of predict- ing the recurrence of eclipses. The changing sit- uations of the planets among the stars were, moreover, diligently recorded, and accurate acquaintance was secured with the movements of the sun and moon. The interpretation in 1889, by Fathers Epping and Strassmaier, of a collection of inscribed tablets preserved in the British Museum vividly illuminated the methods of official Babylonian astronomy in the second century b. c. They were perfectly effectual for the purpose chiefly in view, which was the prepa- ration of yearly ephemerides announcing expected celestial events, and tracing in advance the paths of the heavenly bodies. Further analysis in 1899 by Father Kugler, S.J., of the tabulated data employed in computing the moon's place, disclosed the striking fact that the four lunar periods — the .synodic, side- real, anomalistic, and draconitic months — were substantially adopted by Hipparchus from his Chaldean predecessors.

Greek Astronomy. — .\stronomy, however, no sooner became a distinctively Greek science than it underwent a memorable transformation. Attempts began to be made to render the appearances of the sky intelligible. They were, indeed, greatly hampered by the assumption that movement in space luust be conducted uniformly in circles, round an immobile earth; yet the problem was ostensibly solved by .\pollonius of Perga (250-220 B. c), and his solution, applied by Hipparchus to explain the movements of the sun and moon, was extended by Claudius Ptole- miBus (Ptolemy) to the planets. This was the cele- brated theory of eccentrics and epicycles, which, by the ingenuity of its elaboration, held its own among civilized men during fourteen centuries. Hippar- chus. the greatest of ancient astronomers, observed at Rhodes (146-126 B. c), but is considered as belong- ing to the -Alexandrian school. He invented trigo- nometry, and constructed a catalogue of 1080 stars, incited, according to Pliny's statement, by a tempo- rary stellar outburst in Scorpio (134 B. c). Com- paring, as the work progressed, his own results with those obtained 1,50 years earlier by Timocharis and Aristyllus, he detected the slow retrogression among the stars of the point of intersection of the celestial equator with the ecliptic, which constitutes the phenomenon of the precession of the equinoxes. The circuit is completed in 25,800 years; hence the tropical year, by which the seasons are regulated, is shorter than the sidereal year by just twenty-one minutes, the equinox shifting backward to meet the sun by the annual amount of 50i". Greek astronomy was embodied in Ptolemy's " Almagest " (the name is of mixed Greek and Arabic derivation), composed at .■Mexandria about the middle of the second century A. D. It was based upon the geocentric principle. The starry sphere, with its contents, was supposed to revolve, once in twenty-four hours, about the fixed terrestrial globe, while the sun and moon, and the