Archaeoastronomy is a field that studies how the ancients saw the stars – and how they used their knowledge of them. Ancient people in Egypt, Ireland, Greece, and the Americas were capable of determining the times of astronomical events with great accuracy, and incorporated this into their architecture. The Greeks used advanced knowledge of geometry to study the heavens, but even the Mayans, who had no written language, were able to gain advanced knowledge about the heavens and studied the movement of Venus. People around the world have also made their own interpretations of constellations. While the Greek’s Orion and Great Bear are familiar to us, Ancient Egyptians saw hippopotamuses in the heavens, whereas the Incans drew out llamas.

In Ireland, Newgrange is an architectural structure of ancient times, a grassy mound surrounded by huge stones and with a door that leads into its inner chamber. Its single door points towards the sun during the sunrise on the date of the winter solstice. A “roof box” above the door allows sunlight at that time to flood into the central chambers of the monument.

Astronomy was often tied closely to astrology and the spiritual in the ancient world, as evidenced by the unique swirls etched into the outer rim of stones at Newgrange. We know that shamanism was common in this time period in Ireland; today, shamans are known to take hallucinogens that are believed to invoke spiritual visions. When asked to draw what they saw in their hallucations, the patterns closely resemble those patterns in Newgrange - indicating that the place was likely of religious importance.

Farther south, in Egypt, the Great Pyramids of Giza mark the last standing of the Seven Wonders of the Ancient World. They were built at different times, but must have been constructed with the ultimate plan of all three in mind, due to the way they are oriented together. In particular, the pyramid of Khufu and the pyramid of Khafre are aligned such that, during the sunset on the Summer Solstice, the sun hits the horizon exactly in between them. This resembles one of their hieroglyphs, akhet, which shows the sun setting in between two mountains. The akhet hieroglyph had to do with the afterlife.

Religion in Ancient Egypt included the belief that the Pharaohs were of the stars, and would go back to them upon death. This likely holds the key to understanding the mysterious air ducts in the Great Pyramid (of Khufu), whose angles point to important stars in ancient Egyptian religion: a star in Ursa Minor, Thuban (which was then the North Star), Sirius, and the stars in Orion’s Belt.

The Mesoamericans also built things that had connections to their knowledge of the stars. That includes the city at Macchu Picchu, and the Chichen Itza pyramid. Macchu Picchu includes two towers - one designed for observing the winter solstice, and another for the summer solstice. The Chichen Itza pyramid has a particularly striking feature that plays with shadows. Each face of the pyramid has a serpent’s head at the middle of the base. On the equinoxes, the shadow from the pyramid’s corners set a wavy, serpentine shadow pattern that leads down to the sculptured head – giving the illusion of the snakes slithering down the pyramid.

The Mesoamericans were not the only ancients who designed cities around solstices and equinoxes. In Italy, the Roman city now known as Aosta has star-inspired features, including a main axis of the city's layout oriented to the path of the sun during winter.

Ancient people around the world had an advanced understanding of astronomy, math, and architecture that made these remarkable constructions possible. From the designers of Stone Henge, oriented around the solstices, to the mathematicians of Ancient Greece, who used geometry to find out how far away the sun is from the earth, many ancient cultures were a lot more advanced than are often first assumed.

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To learn more, check out the course "Archaeoastronomy" from the Politecnico di Milano with Professor Giulio Magli on www.coursera.org . Coursera has some lecture-heavy courses but this is not one of them! It's six weeks' worth of pure fun and fascination. : )

On Ancient Greece, Geometry, and Astronomy: See Teaching Textbook's Geometry curriculum.