Egypt Astronomy in ancient Egypt

Egyptian astronomy dates back to the fifth millennium BC, two thousand years further than other ancient cultures such as Mesopotamia or China. Egyptian culture depended on the annual floods of the Nile. Exact time keeping was essential to forecast the flood and for that, precise observations of the stars were necessary. As a result, the usage of a 365-day calendar in Egypt dates back to at least the third century BC, making the Egyptian calendar the oldest 365-day calendar in the eastern hemisphere. The primary focus of this site is not astronomy, but Star Lore, which is folklore based upon stars and star patterns. We try to create a collection of mythical stories about stars and constellations from all over the world. However, to better understand and interpret the stories, a brief history of the astronomy of different cultures might be helpful. This is by no means a scientific paper on the history of Egyptian astronomy, but merely an illustrated collection of highlights of that history, along with some links to what we think are reliable sources on the subject. There have been numerous attempts to interpret Egyptian star charts in hieroglyphic text, but the results are controversial. We found two extensive studies online, one by Alessandro Berio (second source here) and one by José Lull and Antonio Belmonte. Both are intriguing, but we are in no position to evaluate them. We also found an extensive interpretation of the works of S.A. Mackey by Antonios Goyios.

This portion of our site is about the history of ancient Egyptian astronomy. Click here to discover the world of Egyptian Star Lore.

Bits of History of Egyptian Astronomy

Nabta Playa The stone circles of Nabta Playa in southern Egypt date back to the 5th millennium BC - two thousand years before the reign of the Pharaohs. There are (disputed) claims that the circles represent Calendar Circles, indicating the rising of certain stars and the direction of the summer solstice sunrise. An astronomical use of those circles would make Nabta Playa one of the oldest archaeoastronomical sites on Earth. Source: Wikipedia

Nabta Playa Stone Circle (reconstructed at Aswan Nubia museum) Source: Wikipedia

The Decans (ca. 2100 BC) The Decans were 36 groups of stars that rose consecutively on the horizon throughout each earth rotation. The rising times of these stars were used as star clocks since about 2100 BC. The heliacal risings (a star's first visibility at dawn after a period during which it was obscured by sunlight) of the Decans took place ten days apart. With five additional days, these ten-day intervals were the base of the Egyptian calendar, with New year being the first appearance of Sirius - coinciding with the annual flooding of the Nile Source: Wikipedia and G.D. Thompson

Diagonal star table' from the late 11th Dynasty Source: Wikipedia

The Book of Nut (ca. 1850 BC) Dating back to the 12th Dynasty and to Pharaoh Senusret III, the The Fundamentals of the Course of the Stars, was named the Book of Nut after the Egyptian sky goddess. It is a collection of ancient Egyptian astronomical texts on the the movements of the moon, the sun and the planets and the cycles of the stars of the decans. Source: Wikipedia

Goddess Nut, supported by the god of air Shu; by E. A. Wallis Budge Source: Wikipedia

Senenmut's Tomb (1534 BC) The tomb of Pharaoh Senenmut contains the oldest form of astronomical ceiling decoration in ancient Egypt. The ceiling shows a Celestial Diagram consisting of a northern and a southern panel which depicted circumpolar constellations. There have been several attempt to identify the constellations in the diagram. Only one, Meskhetyu (today's Big Dipper) has been identified with some certainty. In 2000, Ove von Spaeth computed and verified the presence of distinctive planetary conjunctions in the chart and dated it as 1534 BC. Sources: Wikipedia, Ove von Spaeth: Dating the Oldest Egyptian Star Map

Bottom portion of the astronomical ceiling Source: Wikipedia

The Sundial (ca. 1500 BC) The earliest sundials known from the archaeological record are shadow clocks dated at about 1500 BC from ancient Egyptian and Babylon. Presumably, humans were telling time from shadow-lengths at an even earlier date, but this is hard to verify. The World's oldest sundial was found in Egypt's Valley of the Kings. Source: Wikipedia

World's oldest sundial Source: Wikipedia

Seti I's Tomb (ca. 1279 BC) The second best preserved astronomical ceiling decoration in Egyptian tombs is that of Pharaoh Seti I. It shows personified representations of stars and constellations which are still open to interpretation. Source: Wikipedia and G.D. Thompson

Astronomical ceiling of Seti I tomb Source: Wikipedia

Interpretation of Egyptian constellations The Decans were an indigenous Egyptian development. Most likely, the do not resemble any of the know Mesopotamian or Greek constellations. While there have been many documented efforts, there is no confirmed interpretation that links certain hieroglyphs in Decan tables without a doubt to specific stars. Although we know the names of the Decans, and in some cases can translate the names (Hry-ib wiA means 'in the center of the boat') the locations of the Decanal stars and their relationships to modern star names and constellations are not known. This is due to many factors, but key problems are the uncertainty surrounding the observation methods used to develop and populate the diagonal star tables, and the criteria used to select decans (brightness, position, relationship with other stars, and so on). Sarah Symons, A Star's Year: The Annual Cycle in the Ancient Egyptian Sky

The Dendera Zodiac (ca. 50 BC) Following the conquests of Alexander the Great in the 3rd century BC, Egyptian astronomy (and astrology) merged with that of ancient Greece and Mesopotamia. The Dendera Zodiac is a ceiling relief in the Hathor Temple at Dendera. It displays a merge of Greek, Mesopotamian and Egyptian Zodiac symbols, showing familiar Greek symbols such as Ram, Taurus, Libra, Scorpio, and Capricorn but also others like the Egyptian flood god Hapy standing in for Aquarius. Source: Wikipedia and H. Rogers. In the first century AD, Claudius Ptolemy made Alexandria in Egypt the center of Hellenistic astronomy. Egypt's legacy also lived on in the works of Arab astronomers such as al Sufi.

Drawing of the Dendera Zodiac by Prosper Jollois and Edouard Devilliers Source: Napoleon and the Scientific Expedition to Egypt

In 331 BC, Alexander the Great founded Alexandria. From that time on, Egyptian astronomy merged with that of ancient Greece.

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