Keeping time

Look: New evidence may finally solve a huge Stonehenge mystery



We still don’t know why Stonehenge exists.

It could have been a gravesite, a monument, an ancient calendar, or possibly a structure we haven’t considered yet.

Researchers have hypothesized that ancient peoples used Stonehenge to track the seasons.

Indeed, parts of the ruins align perfectly with the summer and winter solstice. But there’s more nuance to the calendar’s structure than just marking two big events per year.


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A report published Wednesday in the journal Antiquity suggests Stonehenge could have been a tool to track the passage of time day by day.

T. Darvill / Antiquity

Study author Timothy Darvill analyzed recent research on the stones still standing at Stonehenge, along with fallen ones and holes left behind that likely marked where former stones stood.

He argues that Stonehenge’s structure could have marked a 365-day calendar, with its outer circle representing a single month split into three ten-day weeks.

V. Constant / Antiquity

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“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.”

Archaeologist Timothy Darvill, in a statement.

The gap between the first and 30th stone is a bit larger than the others, suggesting it was probably an entrance.

And the 11th and 21st stone are a bit slimmer than the others, denoting the separation between weeks in the circle.

The main ring of rocks would have represented 30 days total — or 12 months in a year — similar to the calendar we use today.


T. Darvill

But to make a full 365-day year, the builders of Stonehenge would need five more markers.

Hence the five markers in the center of the ring, called trilithons.


This brief month of five days would be a corrective period so that the calendar could follow solar patterns accurately every year.

And to account for leap years, four more stones rested outside the circle, though two are missing today.

It’s unclear if the structure of the calendar was unique to the civilization in northwestern Europe, or if it may have been influenced by other cultures.

T. Darvill


Prior to Stonehenge’s completion, people in Egypt and the Mediterranean built similar calendars that tracked the motions of the sun and moon over the course of the year.

Egypt is home to what’s known to be the oldest 365-day solar calendar on record.

We do know that ancient Egyptians had extensive trade routes dating back thousands of years. How close they got to Stonehenge — and if they traded ideas with the ancient peoples who constructed it — remains unknown.

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“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.”

Timothy Darvill, in a statement.

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