Alfred Wegener: Difference between revisions
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Alfred was directed to undertake a historical and critical study of a set of astronomical tables, the Alfonsine Tables. Commissioned by Alfonso X "The Wise" of Castile in the 13th century, they were used for navigation and time reckoning. They allowed one to find the position of the Sun, Moon, and planets at any hour and minute. They were the tables of reference throughout Europe from about 1330 until Erasmus Reinhold's Prutenic Tables appeared in 1551.
The creation of a
These Alfonsine Tables were now rare books available only in great university libraries. They were written in a difficult form of Medieval Latin and couched in terms of the of the Ptolemaic (Earth-centered) solar system. Moreover, the numerical values in the planetary tables employed base 60 sexagesimal system rather than the decimal system both for angular measurement and for date and time reckoning.
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Alfred began his work in September 1904, comparing the six existing principal Latin editions to eliminate printer's error. He then translated the text from Latin to German. Then, he converted the tables from sexagesimal to decimal values, a task involving about 9,000 calculations. That was the heart of the task, but there was a good deal more.
Alfred provided a correction for the difference between Toledo, Spain -- the 0° of longitude in the tables -- and Greenwich, England -- the 0° of longitude for modern astronomy. He uncovered a systematic sixteen-minute offset in the tables resulting from a discrepancy between the Alfonsine way of calculating the mean time of a transit and the modern method of doing so. Finally, he devised a formal to eliminate a correction in the tables meant to account for the precession of the equinoxes which
He had to provide extensive notes to give astronomical calculators the means to use them. The calculators in question were not machines, but observatory staff whose job it was to perform actual calculations. It required several explanations. The tables for the Sun are used differently
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