As Above, So Below

There is one thing in common all of humanity has had, regardless of where and when they have existed on planet Earth - that is the sky. As long as humans have had eyes, the magical and enticing canopy of the skies has always been above them to be noticed and revered. Therefore, it makes astronomy one of the oldest sciences, as ancient records on stone tablets from Mesopotamia show. The earliest human settlers quickly learnt that their survival was deeply tied to the skies. Food is fundamental to the survival of humans, and food is linked to agriculture and agriculture to the seasons; thus, it is no stretch of the imagination that the survival of humans depended on understanding the skies and the motions that herald the seasons. To navigate our way around the planet, we need a sense of direction and time. All these are fundamental human needs if we are to thrive on planet Earth and are deeply linked to understanding the skies.

Humans tend to attribute agency to things in their lives and the natural environment. There is cause and effect. Droughts brought famine, and rains were essential for successful harvests. If only these could be predicted! The skies held the answers, so gods were placed there to control all that happened on Earth. How do we communicate and connect to the gods? By building monuments on Earth, we are thus gateways to the skies and the heavens above.

This is the backdrop to the field of Archeoastronomy, which only was recognised as a discipline as recently as in the 1960s, while ancient structures stood silently, often in plain sight for hundreds and thousands of years. The discovery that many ancient structures found worldwide were not randomly built but were constructed purposefully in relation to the motion of the skies shed new light on our past. Hundreds and thousands of years later, it is how we piece together the story of humanity before they left written records – it is the world of prehistory, one of enigma and interpretation. All over the world are sites that modern humans have revisited through the lens of astronomy to recognise the remarkable design and purpose of building these ancient structures by our ancient ancestors, a reflection of their intrigue and connection to the skies.

Some themes recur across the world among civilizations that likely never communicated. One of them is the marking of the equinoxes and solstices. These occurrences are related to the position of the sun in the sky and mark the time when day and night are equal (equinoxes), the longest day (summer solstice), and the shortest day (winter solstice) in the northern hemisphere. They mark the start and end of the four seasons.

Let us visit a few of these remarkable sites. Stonehenge in the United Kingdom is thought to have been a calendar marking the summer solstice when it was constructed about five thousand years ago. On that day, the sun rises behind the heel stone, and the first rays shine into the centre directly. Less well-known than Stonehenge is a structure predating it in Africa known as the Nabta Playa stone circle, marking the summer solstice coinciding with the monsoon rains in the Sahara Desert.