The Dendera Zodiac

The Dendera zodiac is a widely known Egyptian bas-relief from the ceiling of the pronaos of a chapel dedicated to Osiris in the Hathor temple at Dendera. It contains images of Taurus and the Libra.

The chapel was begun in the late Ptolemaic period; its pronaos was added by the emperor Tiberius. This led Jean-François Champollion to date the relief correctly to the Graeco-Roman Period. However, most of his contemporaries believed it to be of the New Kingdom.

The Dendera Zodiac
The Dendera Zodiac

The now-accepted date for the relief is 50 BC, since it shows the stars and planets in the positions they would have been seen at that date. The relief has been conjectured to be the basis on which later astronomy systems were based.

What was the Dendera zodiac used for?

The zodiac is a planisphere or map of the stars on a plane projection. It is showing the 12 constellations of the zodiacal band forming 36 decans of ten days each, and the planets. These decans are groups of first-magnitude stars. These were used in the ancient Egyptian calendar, which was based on lunar cycles of around 30 days and on the heliacal rising of the star Sothis (Sirius).

Its representation of the zodiac in circular form is unique in ancient Egyptian art. More typical are the rectangular zodiacs which decorate the same temple’s pronaos.

The celestial arch is represented by a disc held up by four pillars of the sky in the form of women, between which are inserted falcon-headed spirits. On the first ring, 36 spirits symbolize the 360 days of the Egyptian year.

On an inner circle, one finds constellations, showing the signs of the zodiac. Some of these are represented in the same forms as their familiar names (e.g. the Ram, Taurus, Scorpio, and Capricorn, albeit most in odd orientations in comparison to the conventions of ancient Greece and later Arabic-Western developments), whilst others are shown in a more Egyptian form: Aquarius is represented as the flood god Hapi, holding two vases which gush water.

The Dendera zodiac as displayed at the Louvre
The Dendera zodiac as displayed at the Louvre

“The beginnings of astronomy and the calendar in Egypt can be traced back to the third millennium BCE. Evidence for the 365-day solar calendar, for a lunar day-count, and for the observation of stars to divide the night into hours dates to this early period; water clocks and shadow clocks came later.

Throughout pharaonic history astronomy was linked to the notion of a celestial Hereafter and lore about stellar gods. In the first millennium BCE Egyptian culture came under the influence of Babylonian astrological astronomy; from the Hellenistic period down through Greco-Roman times, Egypt was a center of astrology.

The earliest evidence for Egyptian ‘sky-watchers’ dates to the early second millennium BCE. Contemporary texts use the title ‘hour man,’ a descriptive term presumably referring to a person observing the hour-stars. A millennium later the title ‘hour watcher’ is documented.

A 19th century illustration of the Dendera zodiac
A 19th century illustration of the Dendera zodiac, a bas-relief on the ceiling of the Hathor temple at Dendera in Egypt. It is the only complete map of the ancient skies to have survived.

The existence of titles such as ‘chief of hour-watchers’ shows that the profession was organized like others. A Late Period description of astronomer’s duties included

‘knowing the time of the rising and setting of stars, especially Sothis (Sirius), the progress of the sun towards north or south, the proper length of the hours of daytime and night, and the proper performance of rituals, as well as charms against scorpions.'”

The Cambridge History of Science: by Rolf Krauss (#aff)

Where is the Zodiac of Dendera?

The ancient Egyptians were pioneers in astronomy: their expertise played an important role in determining the annual flooding of the Nile, and aligning the pyramids towards the pole star. They were very interested in observing the night sky and phenomena associated with sun and moon.

The relief, which John H. Rogers characterized as “the only complete map that we have of an ancient sky”, has been conjectured to represent the basis on which later astronomy systems were based. It is now on display at the Louvre, Paris. D 38 ; E 13482 ; CM 464