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HISTORY: FICTION or SCIENCE # 7
Episode 131
One on One Video Call W/George
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Transcript:
https://youtu.be/TO1vP6IeFp0
Speaker 0 (0s): Welcome back ladies and gentlemen, thank you for returning participating and that hopefully enjoying this phenomenal series by Anatoli flamenco FICTION or SCIENCE. What is this thing? We call history. We are on the seventh reading chapter two, astronomical. Datings the strange leap of parameter D in the theory of lunar motion.
Nowadays, we have special calculation tables. The so-called cannons whose compilation was based on the theory of lunar motion. They contain the date of each eclipse, the area to be covered by the lunar shadow, the phase, et cetera. See the famous, astronomical Canon of Gunzel. For instance, if an ancient text describes some eclipse in enough detail, we can determine what characteristics of the eclipse had been observed.
The phase, the geographical area, that the shadow passes over, et cetera. The comparison of these characteristics to the referential ones contained in the tables may give a concurrence with an eclipse possessing, similar characteristics. If this proves a success, we can date the eclipse. However, it may turn out that several eclipses from the astronomical Canon fit the description.
In this case, the dating is uncertain. All the eclipses described in the quote, ancient unquote and medieval sources have been dated by the following method. To some extent, at least nowadays the datings of the ancient eclipses are occasionally used in astronomical research. For instance, the theory of lunar motion has the notion of the so-called parameter D the second derivative of lunar elongation that characterizes acceleration.
Let us remind the reader of the definition of elongation figure 2.1 figure 2.1 shows the solar orbit of the earth and the Tellerik orbit of the moon. The angle between the vectors, IES and EMS called lunar elongation, D D the angle between the lines of sight drawn from the earth to the sun and the moon. Apparently it is time dependent and example of the elongation of what Venus can be seen in the picture on right.
Maximal elongation is the angle where the line of sight as drawn from earth to Venus touches the orbit of Venus. One has to know that the orbit in figure 2.1 are shown as circular while being elliptic in reality. However, since the eccentricity is low here, the ellipses are schematically drawn as circles.
Some computational problems related to astronomy require the knowledge of lunar acceleration as it had been in the past. The problem of calculating parameter D over a large time interval as a time function was discussed by the Royal society of London and the British academy of sciences in 1972, the calculation of the parameter D was based on the following scheme.
The equation parameters have lunar motion, including D D R taken with their modern values, and then varied in such a way that the theoretically calculated characteristics of ancient eclipses coincide with the ones given for day-to-day eclipses in ancient documents, parameter D is ignored for the calculation of actual eclipse dates. Since the latter are a rougher parameter, whose calculation does not require the exact knowledge of lunar acceleration alterations in lunar acceleration affect secondary characteristics of the eclipse, such as the shadow track left by the moon on the surface of the earth, which may be moved sideways
Speaker 1 (4m 54s): A little,
Speaker 0 (4m 56s): The time dependence of D was first calculated by the eminent American astronomer. Robert Newton, according to him, parameter D can be de
Published on 4 years, 6 months ago