Vettius Valens

Vettius Valens ( born February 7, 120, † 175 ) was a Greek astronomer and astrologer of the 2nd century AD He wrote the nine -volume work Anthologiae, which is regarded as pioneering work in terms of astrological associations of the week. It was written 150-175 and is the oldest direct evidence of the introduction of the seven-day week based on the names of planets dar.

Background

For the purpose of determining the respective planetary ruler of hour, day, month and year Vettius Valens developed the method of horoskopierten birth. When his own birth he called the first hour after sunset on 13 Mechir (February 7 ) 120 in the fourth year of the reign of Hadrian. As a further basis Vettius Valens chose the first Thoth as Sunday in the first year of the reign of Augustus, where he used the Egyptian calendar as a reference.

Vettius Valens refers, in this context, two further periods for the determination of the annual Regent. As a beginning, he took over the heliacal rising of Sirius. The explicit reference and nomination of the underlying time periods confirms the assumptions that Egypt played an important role in the seven-day planetary week.

Calculation of solar and planetary lengths

In the Anthologiae I, Vettius Valens 20 circulation rules written based on personal calculations. He identified the circumferential lengths of the sun and the planets Jupiter, Mars, Saturn, Mercury and Venus. As a starting point Vettius Valens defined the era of Augustus and calculated the rounds have occurred since then in full years.

For the calculation of Venus, he sat down at the eight-year synodic period in which Venus stands by the 584 -day intervals five times in conjunction. As accounting scheme for the Mercury acted the difference of days that had passed since the first Thoth.