๐“‡ณ The Egyptian Sky

Science Centre Observatory, Jurong ยท Sah, Sopdet, the Imperishable Stars & the 36 decans
โ† Dashboard

For the ancient Egyptians the sky was the goddess Nut, arching over the Earth, her body strewn with stars. She swallowed the Sun each dusk and gave birth to it each dawn โ€” and along her body ran two great families of stars.

The northern stars that never set were the Imperishable Stars (jแธซmw-skw) โ€” eternal, they were where the dead king went to live forever among the gods. Chief of them is Meskhetiu, the Bull's Foreleg (our Big Dipper), and Taweret the hippopotamus (our Draco), who guard the pole.

The stars that rise and set were the Unwearying Stars (jแธซmw-wrแธw). Greatest are Sah (Orion, the soul of Osiris) and Sopdet (Sirius, Isis), who chase each other across the heavens as Isis follows Osiris.

The first clock. Egypt divided this rising band into 36 decans โ€” star-groups whose dawn risings, ten days apart, marked the weeks of the year and, through the night, its hours. That is the origin of the 24-hour day, and of a 365-day calendar (36 ร— 10 + 5). Sopdet's dawn return each summer announced the Nile flood and the New Year.

๐Ÿ‰๐Ÿชท The same stars, other names. Sah is China's ๅƒ and India's Mแน›gaล›ฤซrแนฃa; Meskhetiu is the Northern Dipper ๅŒ—ๆ–—. Each figure below shows its matching Chinese mansion and Indian nakshatra.

Two families of stars โ€” Imperishable & Unwearying

The circumpolar stars that never set (gold, near the pole) versus the stars that rise and set (cyan). Tap a family to light up its figures on the map and table.

The sky map โ€” Egypt's figures

Strip map
Circle chart

โ† swipe the strip sideways โ†’

Figure โ†” Western sky

FamilyEgyptian figureWesternStars

Every star of a figure

Pick a figure to see it drawn over the real stars โ€” with its myth and the Chinese mansion & Indian nakshatra it shares.

The 36 Decans โ€” the star-clock โ€” the origin of the hour

The band of rising stars split into 36 "weeks" of 10 days. Each decan's dawn rising began a week; through the night their risings counted out the hours. Tap a decan to read it โ€” Sopdet (Sirius) is the first.

โณ Why our day has 24 hours. At night about 12 decans rose in turn โ†’ 12 night hours; the Egyptians gave the day 12 to match, and we still keep their 24. And 36 decans ร— 10 days + 5 feast days = the 365-day year.
๐“‡ณ Which figures are up tonight? ๐Ÿ‰ Chinese Sky ๐Ÿชท Indian Sky

Securely identified Egyptian sky-figures are few โ€” the sky is known mainly from tomb-ceiling art (Senmut, Seti I, Dendera), not a star-list โ€” so this is a faithful, representative selection: Sah = Orion, Sopdet = Sirius, and Meskhetiu = the Big Dipper are well established; Taweret (Draco) and the mooring-post are the generally accepted northern group, though exact stars are debated. Figures are drawn from their brighter stars at Hipparcos J2000 positions. The 36 decans are shown as the timekeeping ring they formed, anchored on Sopdet; individual decan star-identifications (beyond Sopdet) remain uncertain. Shared-star links use the same coordinates as The Chinese Sky and The Indian Sky. Live view: The Egyptian Sky Tonight.

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