Path: utzoo!mnetor!uunet!lll-winken!lll-tis!ames!oliveb!sun!livesey From: livesey@sun.uucp (Jon Livesey) Newsgroups: sci.misc Subject: Re: Digression Message-ID: <51010@sun.uucp> Date: 27 Apr 88 11:04:50 GMT References: <5017@uwmcsd1.UUCP+ <2790@gryphon.CTS.COM> <1221@uop.edu> <3103@whutt.UUCP> Organization: Sun Microsystems, Inc. - Mtn View, CA Lines: 95 In article <3103@whutt.UUCP>, mls@whutt.UUCP (SIEMON) writes: > In article <1439@uop.edu>, todd@uop.edu (Dr. Nethack) writes: > > BUT the notion of an astronomical configuration corresponding to an individual > and in some sense following that individual through life as a determinant in > the individual's fortune (I've been non-sexist here; actually all the original > cases are for males) goes back to circa 300 B.C. -- the first one known is on > a mountainside carving glorifying one of the Seleucids (Antiochos umpty-umpth.) > The classical form of the horoscope developed very rapidly in the next 100-200 > years. Read Neugebauer for the data (and especially for the fascinating story > of the development of Mesopotamian astronomy.) > Neugebauer O. "The Exact Science in Antiguity" Dover 1969. Neugebauer O. "A History of Ancient Mathematical Astronomy" Springer-Verlag 1975. Leaving aside the motivations, one of the most striking aspects of Babylonian astronomy was the primitive nature of the tools employed. They seem to have made do with the sun-stick [gnomon]; an upright stick whose shadow, which one can measure on successive days, traces out a projection of the locus of the Sun's path. If you sit in a churchyard, you can imagine that you feel the motion of the Earth, by carefully watching the movement of the shadow of the spire of the church. Even if you don't do very exact measurement, you can catch the extreme positions of the Sun's shadow each day, to tell noon, and the extreme positions for the year, which are at the Equinoxes. Ptolemy(*) calculated the diameter of the Earth (wrongly) based on the lengths of shadows cast by a gnomon at Alexandria, compared to one farther South at (I think) Suez. After a few years' experience with a gnomon, you can forecast planting season, and so on. Identical sun-sticks are in use in 'stone age' societies to this day, for example, Borneo. There are ample reasons to do simple practical astronomy, without dragging in astrology, although the astrologers will always be on the fringes somewhere. It's also true that you can use the night-time analogue of the gnomon, a hole to squint through, and a vertical shaft, to make sightings of stars. However, you only want to track a few objects, and the obvious ones will be the Moon, Venus, and some others. Alternatively, you can just track major events which need no instruments at all, rises, settings, and eclipses. To get precision, you have to track the same objects for a very long time, in the (perhaps unconscious) hope that the various systematic, as well as random, errors will cancel out. That's what the Babylonians did systematically from around 700bc onwards. Fortunately, long-lived empires encourage record-keeping, and even when the Babylonian Empire fell, first to Cyrus the Great, around 550bc, and later to Alexander, around 330bc, the conqueror appears to have encouraged bureaucratic, religious, and scientific continuity, for political reasons. (Alexander did the same in Egypt, of course) One way or another, records survived, and observations continued to be made. Around 150ad, Ptolemy(*) said he had records of eclipses back to 747bc. Observations over such a long period were enough to allow the development of his deterministic (but incorrect) theory of planetary motion, based on epicycles. As well as eclipses, the Babylonians collected observations of Venus accurate enough to allow dating of earlier records back to around 2000bc. The Babylonians themselves might not have been able to carry out this dating over very long periods since they had no very good model of the movement of astronomical bodies, yet astronomical prediction is always an attractive goal, and the next few hundred years of astronomy saw the development of such models, mainly by the Greeks, the Arabs, and finally Western Europe. For an introduction to the development of increasingly sophisticated Greek cosmologies, leading up to the present day, you can do worse than the following book, which is a very readable introduction: Durham F. and Purrington R. D. "Frame of the Universe" Columbia University Press 1983. (*) Ptolemy the Astronomer (Claudius Ptolemaeus, 85-165ad), who worked during the reign of Hadrian, an Emperor who was an enthusiast of Hellenic science and culture, and who visited Greece in 125ad and Alexandria in 130ad, *not* Ptolemy the King, Alexander's heir (367)-305-285bc, and Cleopatra's ancestor, who helped Alexander found Alexandria, and later encouraged the development of Hellenic culture and science in Egypt, and may have founded the famous museum and library. When Alexander died in 322bc, his Empire, after a short interregnum, broke up into three parts; Macedonia itself, where his family lived, but not for long since they were 'liberated' by Rome around 150bc, Egypt, which fell to General (King) Ptolemy, who took the precaution of hijacking Alexander's body, and the Seleucids, mentioned above, who reigned in Asia Minor, and erected a great empire under Antiochus III, afterwards making the mistake of fighting Rome for the remains of Macedonia, losing to Scipio Africanus and his brother Scipio Asiagenus at Magnesia, and eventually losing their independence in sad dribs and drabs under Antiochus IV. There were some rather pathetic minor characters, too, like Demetrios Poliorketes 294-288bc, who mainly tried to arrange alliances with the big boys. Demetrios (The Besieger of cities) thought of himself as a great military genius, and Alexander's reincarnation, but all that is left of him is a few coins, one of which sits on my desk.