New analysis has discovered how Stonehenge may have functioned as an ancient solar calendar, helping people keep track of a year that lasted 365.25 days, calibrated by the alignment of solstices.
The research, published in the journal Antiquity, examines how the large sandstone blocks called “sarsens” appear to show a calendar of 12 months, each consisting of 30 days that were divided into 10-day “weeks.” Calendars like these were developed in ancient Egypt, which means the Stonehenge calendar system could be derived from elsewhere.
A similar calendar was developed in the eastern Mediterranean after 3000 BC and was adopted in Egypt as the Civil Calendar in approximately 2700 BC. It was widely used at the start of the Old Kingdom in 2600 BC, the study notes.
“The clear solstitial alignment of Stonehenge has prompted people to suggest that the site included some kind of calendar since the antiquarian William Stukeley,” said lead study author Timothy Darvill in a press release. “Now, discoveries brought the issue into sharper focus and indicate the site was a calendar based on a tropical solar year of 365.25 days.”
The crux of Darvill’s hypothesis lies in the fact that Stonehenge’s sarsens were added during the same phase of construction in approximately 2500 BC, were sourced from the same area and remained in the same position – suggesting they were meant to work as a single unit.
By comparing Stonehenge to other ancient calendars, Darvill was able to work out how it functioned as a calendar.
“The proposed calendar works in a very straightforward way. Each of the 30 stones in the sarsen circle represents a day within a month, itself divided into three weeks each of 10 days,” said Darvill, noting in the release that certain stones in the circle mark the start of each week.
Leap years were also taken into account in his analysis.
“The intercalary month, probably dedicated to the deities of the site, is represented by the five Trilithons in the centre of the site,” he explained. “The four Station Stones outside the Sarsen Circle provide markers to notch-up until a leap day.”
In Darvill’s proposed framework, the winter and summer solstices would be framed by the same pairs of stones every year.
“Finding a solar calendar represented in the architecture of Stonehenge opens up a whole new way of seeing the monument as a place for the living,” he said. “A place where the timing of ceremonies and festivals was connected to the very fabric of the universe and celestial movements in the heavens.”
