Astronomy Fundamentals

History of Astronomy

What did ancient African cultures know about astronomy?

The ancient Egyptians built their pyramids and other great monuments with a clear understanding of the rhythms of rising and setting celestial objects. The Egyptians established the 365-day solar year calendar as early as 3000 B.C.E. They established the twenty-four-hour day, based on nightly observations of a series of thirty-six stars (called decan stars). At midsummer, when twelve decans were visible, the night sky was divided into twelve equal parts—the equivalent to hours on modern clocks. The brightest star in the night sky, Sirius the “Dog Star,” rose at the same time as the Sun during the Egyptian midsummer; this is the origin of the term “dog days of summer.”


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