Archaeoastronomy is the ultimate combination of archaeology, anthropology, mythology, astronomy and history. But what is the use in encompassing such a broad range of disciplines, you might ask. Astronomy is the oldest science in the world; so why not study how ancient civilisations interpreted phenomena in the sky, and what impact this had upon their culture? In seeking knowledge of those who lived in ancient times, we not only discover how science has developed throughout past centuries but we may also find a greater understanding of how we came to be. Thus, importantly, archeoastronomy is not simply the study of ancient astronomy, but it also considers the influence of astronomy upon culture.
It can be argued that the first archaeoastronomical observation was made in the 18th century by William Stukeley when he observed that the principal axis of Stonehenge was oriented to the direction of sunrise at summer solstice. Other megalithic objects can also be examined, such as the Great Pyramids of Giza, which are thought to have an alignment similar to the belt of Orion. Many astronomical artefacts have also been found all over the world, from sand paintings to ancient tablets and scrolls.
Archaeoastronomers are often split into two groups: Green (generally practised in Europe) and Brown (mainly practised in the Americas). Green archaeoastronomers focus primarily on statistical surveying where there is a lack of historical and anthropological evidence. This tends to result in accusations that the cultural context of social practice has been missed. For example, as the discipline emerged in Britain, people began to question the purpose and meaning of the vast amount of prehistoric sites, typically stone circles. Since no records and myths have been left behind, Green archaeoastronomers must approach it mathematically, trying to align sites with links to the heavens.
In contrast, Brown archaeoastronomy uses great amounts of ethnographic and historical evidence in relation to astronomical sites, yet on the other hand they tend to under-represent a statistical analysis. In looking at the Mayan Temple of Chichen Itza, Brown archaeoastronomers were able to evaluate human documents to establish the importance of astronomy in their culture. Thus, it was deduced that the Mayas had a very strong following of Venus. This has been stated due to the distinctive colours on El Caracol, a round structure theorised to have been an observatory which has doors and windows aligned to the path of Venus as it traverses the sky.
Many different empires all over the world reflect such inspirations in the layout of their empires. For instance, the Incas placed their capital in the centre of the empire with four quarters radiating outwards from the origin – which interestingly relates to the appearance of the Milky Way in the night sky; in one season the Milky Way bisects the sky, and in another it bisects the sky perpendicular to the previous season.
On the other hand, the Forbidden City in Beijing is laid out to observe five directions; North, South, East, West and Centre. With the Forbidden City in the centre of Beijing, one would approach the Emperor from the South, so that he appeared in front of the circumpolar stars whereby the heavens would revolve around him. The full name of the Forbidden City is actually the Purple Forbidden City where ‘Purple’ refers to the North Star. The constellation containing the North Star was called the Constellation of Heavenly God, and the star itself was called the ‘Purple Palace’. Because the Emperor was supposedly the son of the heavenly gods, his central and dominant position would be further highlighted by the use of the word ‘purple’ in the name of his residence.
One particularly astounding item that is found in the Forbidden City today is an 82cm high celestial golden globe surrounded by coiling dragons and inlaid with pearls which represent the stars. It is found in the Treasure Gallery which lies in the Palace of Tranquil Longevity in the northeast of the Palace Museum.
China is one of the first countries to have begun astronomical research, with written records of celestial events dating back to circa 40 centuries ago. It has been noted in some fields, the Chinese were roughly 20 centuries ahead of Western practices. In 613 BC, Chinese astronomers made observations of Halley’s Comet and have kept record of every appearance since then; a total of 31 occasions over 2500 years. Furthermore, since approximately 288 BC, the Chinese started observing sunspots using only the naked eye believing them to be dark gaseous masses or “birds landing on the surface of the sun”. In addition, they developed a lunar calendar which was used in ancient times to predict the weather.
One of the oldest observatories in the world can also be found in China. The Beijing Ancient Observatory was built in 1442, and consists of eight great bronze instruments, including an armillary sphere (measures the coordinates of celestial bodies); a quadrant (measures altitudes and zenith locations of celestial bodies); a theodolite (measures both altitude and azimuth coordinates); an astronomical sextant (measures angular distance between celestial bodies as well as the angular diameter of the moon and sun); and a celestial globe (determines the time in which the celestial bodies will rise and set). Many were originally made by the Jesuits and with their use, the Chinese could track the motions of planets and stars and assist sea navigation. Muslim scholars were often recruited for their expertise with these instruments.
Although archaeoastronomy is a relatively new subject, there are currently many active organisations, such as the ISAAC (International Society for Archaeoastronomy & Astronomy in Culture) and the SEAC (European Society for Astronomy in Culture) which both try to enhance the subject by linking it with other studies. There is also a South American organisation which aims to further understand indigenous tribes through their views on astronomy, thus linking anthropology to archaeoastronomy.
The breadth that archaeoastronomy offers excellently encompasses so many different views, resulting in the cooperation between people of all backgrounds and cultures which is unlike any other subject today. Being an astronomer myself, I love the idea of archaeoastronomy as it would allow me to combine not only my passion for the stars but also my love of ancient history and exotic cultures; the variety of civilisations to explore is limitless.
Image: Andy Oakly on Flickr