The northern hemisphere is less than three weeks away from the Spring Equinox, a day of celebration and ceremonies at Stonehenge, which many believe was aligned by its builders to point to the rising sun on this and the other quarterly seasonal events. While that function seems to work well, some have wondered if the entire structure was built to be an ancient calendar for tracking every day of the 365.25 day tropical year, not just the solstices and equinoxes. Believe it or not, that has never been proven at this extensively studied monument. That may change with a new theory … and an odd calendar.
Bournemouth University archaeologist Timothy Darvill is the author of a new study published in the journal Antiquity explaining how his Stonehenge calendar theory begins with the thirty sarsen (sandstone) stones originally forming what is now the most recognizable outer circle of Stonehenge. Those sarsens have been proven to come from the same quarry and brought to Wiltshire during the construction phase which occurred around 2500 BCE. That most likely means they were there as a unit … but for what purpose?
“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.”
Darvill theorizes that the 30 sarsen stones each represented a day in a 30-day month. He noticed stones S1, S11 and S21 are slightly different than the others, so he thinks those represented the first day of three 10-day weeks. Doing the math, that only gives a year of 360 days. While unusual, that calendar structure was used by earlier cultures in the eastern Mediterranean and in Egypt. Of course, they went out of whack eventually due to those 5.25 missing days. Darvill proposes some inner stone settings solved this problem at Stonehenge.
“Completing the basic tropical year requires an additional five days: an intercalary month of days known in later calendars as epagomenal days. The five components of the Trilithon Horseshoe, situated prominently in the centre of the structure, fit this role. Working from the north-east, they grow incrementally in stature, with the tallest—known as the Great Trilithon (S55 and S56, and lintel S156)—to the south-west … adding the intercalary month gives 365 solar days.”
That leaves the .25 days which modern calendars fix with leap years of 366 days. The four Station Stones in the inner Station Stone Rectangle set up during a separate phase of construction could have been used as tallies to remind Stonehenge calendar keepers to add a sixth day every fourth year.
If Darvill is correct and Stonhenge is truly a working and fairly accurate annual calendar, does this mean every day could be a celebration there? For now, it’s a topic for discussion and debate among historians. Is it really a calendar? Did the locals figure it out on their own or learn/steal it from another culture?
Could modern humans live under such a calendar? Probably not – it has less Mondays but also longer work weeks and less weekends.