Sothis year

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Definitions for the tropical year

The term Sothis year (also Sopdet year ) originally referred to the calendar period between two heliacal rises of the star Sirius in ancient Egypt .

background

With the beginning of the Middle Kingdom , the duration of a Sothis year in connection with the coffin texts and diagonal star clocks was additionally transferred to the periods between two Sirius culminations or between two acronymic Sirius falls .

Before the introduction of the Egyptian administrative calendar , on which the Egyptian civil lunar calendar was based, the Egyptians based themselves on the Sothis year, which, with an average of 365.250015 days, provided the original division of the Egyptian calendar year and roughly corresponded to the Julian calendar . The seasons of Sothisjahres shifted compared against the actual solar year on average about every 126 years by one day.

Comparison of solar and Sothis years (period 2770 to 1500 BC)
Observation site 1 Sothis year 1 solar year deviation Postponement from one day to:
Nile Delta 365.25001 days 365.24208 days 0.0079298 days 126 years + 39 days
Elephantine 365.25002 days 365.24208 days 0.0079417 days 125 years + 11 months

See also

literature

  • Rolf Krauss: Sothis and moon dates: studies on the astronomical and technical chronology of ancient Egypt. Gerstenberg, Hildesheim 1985, ISBN 3-8067-8086-X .
  • Christian Leitz : Studies on Egyptian Astronomy. Harrassowitz, Wiesbaden 1991, ISBN 3-447-03157-3 .
  • Alexandra von Lieven : Floor plan of the course of the stars: The so-called groove book. The Carsten Niebuhr Institute of Ancient Eastern Studies (among others), Copenhagen 2007, ISBN 978-87-635-0406-5 .
  • Siegfried Schott : Ancient Egyptian festival dates. Publishing house of the Academy of Sciences and Literature, Mainz / Wiesbaden 1950.

Individual evidence

  1. ↑ Jean Meeus: Astronomical Algorithms: Applications for Ephemeris Tool 4, 5. Barth, Leipzig 2000 for: Ephemeris Tool 4.5 according to Jean Meeus: Umrechnungsprogramm, 2001 .
  2. ↑ a b From the summer solstice to the next summer solstice, based on the period 2770 BC BC to 1500 BC Chr.