This is a longer version of something I wrote for an online astronomy course I’m doing.
Ancient monuments such as Stonehenge, Chacon Canyon and Chichen Itza were clearly built with astronomical functions in mind. There are many alignments in these structures which, when used, predict solstices, equinoxes, moon positions, star positions and even eclipses! Those who argue that they are evidence of alien intervention underestimate the knowledge-base of ancient civilisations.
Knowledge of the movements of heavenly bodies was of vital importance. There were so many practical reasons for this knowledge. Firstly, the people needed a calendar in order to carry out activities such as crop planting and hunting in different seasons– the sun was a convenient object which determined the length of daylight in latitudes away from the equator. The moon was also a convenient ‘clock’ which went through phases in a predictable way and formed the time-interval of the month.
Knowledge of how the constellations changed throughout the year would consolidate understanding of time-intervals. Hence, in Ancient Rome, the year was divided up – first of all into ten months and later into the more familiar twelve months. We can see how much the religion of the Romans was incorporated into sky observations by noting the names of the months and days of the week.
Knowledge of the sun’s, moon’s and star’s movements was also important for navigation. The Ancient Greeks used instruments such as the astrolabe which enabled them to predict when a star would rise.
In the northern hemisphere the star named Polaris appears to be stationary and the other stars rotate round it. This would have been observed by prehistoric people and would have been a reliable means of navigation at night. The Great Bear constellation appears to rotate during the night and would also have been used for navigation and time-keeping before the advent of clocks.
Finally we should remember that religious beliefs were part and parcel of astronomical knowledge in ancient times. The structures I mentioned at the beginning were most likely overseen by priest-astrologers. For example, the Aztecs carved a Megalithic calendar stone known as Montezuma’s Watch which is 12 feet in diameter and intricately carved with astronomical details and life-cycles which are concerned with ceremonial ritual as well as astronomical alignments. According to Aztec religion the world passes through five ages and Quetzalcoatl – one of their gods – was the ruler of the second era. The priest-astrologers had to know when was the appropriate time for a human sacrifice!
Recent research has established that Stonehenge was a meeting place for thousands of people who came from as far away as Scotland.1 It was not only an observatory but a social centre for ceremony and feasting.
We may never know the details of our ancestor’s beliefs but we can be sure they included veneration of the sun, moon, stars and planets. There are many puzzles remaining as to the exact function of many of these structures but there is no need to invoke aliens to explain them. Indigenous people were very knowledgeable and there were vast numbers of people with the skills to build them.