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Re: The Star of Bethlehem and Navigation
From: Geoffrey Kolbe
Date: 2009 Jan 01, 08:29 +0000
From: Geoffrey Kolbe
Date: 2009 Jan 01, 08:29 +0000
To answer Marcel's question directly, the precision of modern astronomical programs to predict the positions of astronomical bodies at any given time depends on our knowledge of delta T, which is basically a term to account for the slowing of the earth's rotation. Various estimates of delta T have been made by various authors. That most respected currently is probably the work of F. R. Stephenson and L. V. Morrison, "Long term fluctuations in the earth's rotation 700 B.C. to A.D. 1990", Philosophical Transactions of the Royal Society, Vol. 351, pp 165-202, (1995). From an assembled collection of ancient observations of solar and lunar eclipses, Stephenson and Morrison distilled curves of best fits to the data for delta T, with an estimate of an error of "not more than 8 minutes". So, modern computer programs which can be used to recreate ancient astronomical phenomenon will have a formula for delta T built in. However, the timings of astronomical phenomenon calculated by these programs for around 2 BC could be off by +/- 8 minutes. Now, +/- 8 minutes of time corresponds to +/- 2 degrees of longitude, so this is the sort of error we can put on Koch's estimate of the longitude of where Jesus would be born. Rather than pinpointing Bethlehem, it would seem the best Koch can do is to say the King of the Jews was born "somewhere in Judaea" which would be unsurprising. Kock might say that astronomers in those days would have had current observational data and so be able to pinpoint the place where the time of the heliacal rising of Venus would coincide with its turning from retrograde to direct with greater accuracy. I have not read Koch's book, so I do not know if that is his argument. But if it is, my response would be a pithy Anglo-Saxon epithet! On the matter of lunar occultation, Stephenson and Morrison report that there are "many" records of occultations of the planets and stars by the moon. "However, owing to the brilliance of the moon, it is difficult for the unaided eye to decide whether or not an occultation is actually taking place unless the occulted object is extremely bright..." which leads to large uncertainty in the timing of such events. From this, I would not hold out much hope of a lunar occultation giving the Three Wise Men a pointer to a manger in Bethlehem. Geoffrey Kolbe --~--~---------~--~----~------------~-------~--~----~ Navigation List archive: www.fer3.com/arc To post, email NavList@fer3.com To , email NavList-@fer3.com -~----------~----~----~----~------~----~------~--~---