Most Bible Students have probably never even heard of Claudius Ptolemy, but he has greatly influenced how we understand Biblical chronology, and therefore prophecy concerning Jesus. Ptolemy was an ancient astronomer and mathematician upon whose works modern historians base much of their data concerning the Jewish chronology from the time of the captivity and then the release of the Jews to about the rise of Alexander the Great. The dates of Nebuchadnezzar’s and Cyrus’ reigns and exploits are assumed to be fixed by Ptolemy’s seven lunar eclipses dated from 747 BCE TO 330 BCE. However, in any given year there could be a total of seven lunar and solar eclipses, five of the sun and two of the moon or four of the sun and three of the moon. The smallest number of eclipses that could occur in one calendar year is two, both of the sun. To complicate matters even further, there are some 70 eclipses in any given 18 years period. Moreover, the solar eclipses occur one third of the way around the earth in every 18-year cycle. Thus, a solar eclipse will occur in the same place at the same longitude every 54 years. Some 600 lunar eclipses occurred worldwide from 747 to 330 BCE, over 300 of which could have been observed in Babylon. Why, therefore, has Claudius Ptolemy used only seven to establish his “Canon of the Kings”? Many astronomers had been asking this question for centuries. However, Ptolemy’s work for dating the history of ancient Babylon and Persia has been used for the past 400 years by historians interested in Babylonian and Persian chronology for at least the four centuries preceding Alexander the Great. Notice what the historian Humphrey Prideaux D. D. said about Ptolemy’s cannon in 1836:
“Ptolemy’s canon being fixed by eclipses, the truth of it may at any time be demonstrated by astronomical calculations, and no one has ever calculated those eclipses but has found them fall in the times where placed; and, therefore, this being the surest guide which we have in chronology, and it being also verified by its agreement everywhere with the Holy Scripture [Prideaux’s understanding], it is not for the authority of any other human writer whatsoever to be receded from.” [“Old and New Testament Connected in the History of the Jews and Neighboring Nations”; p. 242]
This exceedingly favorable analysis of the importance of Ptolemy’s cannon is held to this day among historians. Lloyd and Marshall, world renown chronologists, regard Ptolemy’ cannon as “the most precious monument of antiquity.” Yet, this decidedly optimistic outlook of Claudius Ptolemy’s method of fixing historical data was not always held by world prominent historians. Consider, for example, what Plutarch said:
“As for his [Solon’s] interview with Croesus, some think by chronology that it is fiction. But when a story is so famous and so well attested. I do not propose to reject it out of deference to any chronological canons, so-called: which thousands are to this day revising, without being able to bring their contradictions into any general agreement” (Plutarch, Solon, XXVII, Loeb edition).
The historical event of which Plutarch is speaking occurred in the Babylonian period. It concerned a documented meeting between the philosopher, Solon, and King Croesus of Lydia. However, some who experimented in dating history according to astronomical data, showed some chronological discrepancies with the events that were already accepted. Yet, there was great disparity between the chronological cannons of different historians of Plutarch’s day, which they were unable to correct between themselves. Since eclipses are repeated every 18 years, as noted above, if one used the wrong astronomical information, one could be in error from 18 to 54 years. The error would depend upon the eclipse in mind and the erroneous eclipse taken in consideration when calculating one’s data. This is what Plutarch was complaining about, and his disagreement over the methods used for that period of history was shared by others as well. Note what is recorded concerning Themistocles:
“Thucydides and Charon relate that Xerxes was then dead, and that it was his son Artaxerxes that Themistocles addressed himself. But Ephorus, Dinon, Clitarchus, Heraclides, and several others, write that Xerxes was then upon the throne. The opinion of Thucydides seems most agreeable to chronology, though this is not perfectly well settled” (Themistocles, XXVII, Langhorne’s translation).
Part of the confusion one deals with regarding using data about eclipses in the reigns of ancient monarchs is that the ancient data is often very vague as to where the eclipse appeared in the heavens and even the time of day or night and season of the year. The data is also lacking as to the magnitude of the eclipse, whether partial or total etc. This causes the historians to play the ‘identification game’ – to which eclipse is the ancient record under consideration referring? If this is not bad enough, imagine the problem the occurs for us today when an ancient record is a fraud – that is, the eclipse was not observed at all, but was manufactured by the ancient source whose works are studied by a modern historian. Remembering that Claudius Ptolemy is highly regarded among modern historians who use his alleged findings to date ancient Babylonian and Persian histories, he has been under criticism for quite some time among the scientific circles. Notice: The claim that Claudius Ptolemy ”deliberately fabricated” many of his observations is not new. Astronomers have questioned Ptolemy’s observations for centuries. As early as 1008 AD, ibn Yunis concluded that they contained serious errors, and by about 1800, astronomers had recognized that almost all of Ptolemy’s observations were in error. In 1817, Delambre asked: “Did Ptolemy do any observing? Are not the observations that he claims to have made merely computations from his tables, and examples to help in explaining his theories?” (J.B.J. Delambre, Histoire de l’Astronomie Ancienne, Paris 1817, Vol. II, p. XXV. Quoted by Robert R. Newton in The Moon’s Acceleration and Its Physical Origins [MAPO], Vol. I, Baltimore and London: The Johns Hopkins University Press, 1979, p. 43.) The New Testament says we should not permit our own lives to be squeezed into the world’s mold (Romans 12:1-2). Neither should we try to squeeze Biblical chronology into the timeframe the world has set up for the world leaders who have affected Biblical history. Our God is a great God. He alone is able to see the end of a matter from the beginning. He knew the name of the king who would set Israel free from captivity even before this king was even born. He revealed his name through the prophet Isaiah (Isaiah 44:24-28) and said he would use Cyrus to build both Jerusalem and the Temple. When we consider this Scripture with Daniel 9:25, there is little doubt that whatever historians or theologians conclude concerning the time of the Cyrus’ edict, he did give a command to restore and rebuild Jerusalem, and God charged him to do so. One may say whatever he wishes concerning Artaxerxes Longimanus (the king most Biblical scholars begin dating the 70 Weeks Prophecy), but the Bible itself names Cyrus as the one who wrote the decree to restore and build Jerusalem and the Temple.
 The second century astronomer (cir. 70-161 AD) upon whose work so much of modern understanding of ancient Babylonian and Persian chronology is based.
 Ptolemy said there were three lunar eclipses in the first and second years of Merodach-baladin of Babylon (March 19, 720 B.C.; March 8, 719 and September 1, 719), another eclipse happened occurred in the fifth year of Nabopolassar (April 22, 600 B.C.), another in the seventh of Cambyses (July 16, 522 B.C.), and two more in the twentieth and thirty-first years of Darius Hystapses (November 19, 501 B.C. and April 25, 490).
 “Since eclipses of sun and moon are possible only when the sun is near one of the nodes of the moon’s orbit, eclipses, in general, will occur at intervals of about 6 months. Since the lunar eclipse limits are smaller than the solar, it is possible that no eclipses of the moon will occur in any calendar year. Two solar eclipses must occur under these conditions, however. In this century there are 14 years when only two solar and no lunar eclipses take place. Under the most favorable circumstances there may be as many as seven eclipses, two of the moon and five of the sun or three of the moon and four of the sun, in any one year…. From A.D. 1901 to 2000 there will be a total of 375 eclipses, according to Oppolzer’s ‘Canon der Finsternisse,’ 228 of the sun and 147 of the moon; an average of nearly four per year” (The Elements of Astronomy, by Edward Arthur Fath, 1944, pp. 166-167; see Theodor von Oppolzer, Canon of Eclipses, 1962, Dover reprint, or Oppolzer’s 1887 work).
 “Each individual eclipse, whether of the sun or moon, belongs to a series…. Though an eclipse repeats itself only after eighteen years, there are several eclipses of some kind each year. This is because there are many series going on all the time; there are about 28 series of lunar eclipses, and 42 of solar. Thus there must be a total of about 70 eclipses in every 18 years, or nearly an average of four a year, including eclipses of both sun and moon” (Skilling & Richardson, Astronomy, 1949, p.249).
 Skilling and Richardson, pp. 249-250
 The Encyclopedia Britannica (11th ed.) says that Ptolemy’s canon is “the only authentic source of history of Assyria and Babylonia before the recent discoveries at Nineveh” (article on Chronology).
 Dr. Robert R. Newton, noted physicist, in his book: The Crime of Claudius Ptolemy writes: “In Chapter VII.4 of the Syntaxis [Almagest], Ptolemy says that he has measured the coordinates of all the stars that it is possible to observe, down to stars of the sixth magnitude. He identifies the instrument with which he made the measurements, he describes the procedure that was followed, and he presents the alleged results in his star catalogue. However, we proved in Chapter IX above that the coordinates were not obtained by measurement at all. They were not obtained with the instrument that Ptolemy claims to have used, they were not obtained by the method that he claims to have used, and they were not obtained by any other instrument or procedure of observation. They were fabricated, and Ptolemy lied about what he did” (p. 353).
 In contrast to my attitude is one taken in the Interpreter’s Dictionary of the Bible – Ezra and Nehemiah, the Books of – Volume 2, page 217, and generally throughout the article the position is taken that sources other than the Bible are to be taken as more credible than the word of God. For example in ‘b. Interruption in the building of the temple’ the author assumes “the Chronicler’s ignorance of the facts” concerning the time the building of the Temple was begun. He also noted a contrast between the age of the Levites who were inducted into the service of the Temple, age 20 in Ezra 3:8 and age 30 in Numbers 4:3. If, however, he had thought the word of God to be correct, he might have continued his search and found that David changed this law in 1Chronicles 23:24, 27-32; apparently because the duties of the Levites changed dramatically after the Tabernacle was fixed at Jerusalem and not carried about as it had been up to the time David made a permanent place for the Arc in Jerusalem. The author concludes this section with these words: “None of the information for the period from 538 to the beginning of the building of the temple in 520, except perhaps some proper names, is historically credible.” Sadly, this is the position we all must take, if we use secular chronology as the framework of the word of God. Men make mistakes, and men who build upon the foundation of data gleaned from the ancient secular historical accounts (which, by the way, do not agree among themselves), prepare for themselves and posterity a kind of ‘Tower of Babel’ – impressive to all who build upon the name of man, but God is not in it, and all the work therein is doomed to failure.
 This blog is largely based upon the work of Dr. Ernest Martin: “Chronology: The Key to Prophetic Understanding.”