5 June 2025 The Future is the Product of the Past

The Celts’ Astronomical Secrets: The Chão de Lamas Lunula and the Coligny Calendar Connection

A groundbreaking study published in the journal Palaeohispanica has shed light on the ancient timekeeping practices of the Celts, centering on a unique piece of jewelry known as the lunula from the Chão de Lamas treasure in Portugal. Conducted by Professor Roberto Matesanz Gascón from the University of Valladolid, the research posits that this intricately designed gold artifact may hold crucial information regarding the synchronization of lunar and solar cycles within the Celtic calendar.

Traditionally viewed as a mere decorative item, the lunula—shaped like a half-moon and discovered in Chão de Lamas (Miranda do Corvo, Coimbra)—has now been reinterpreted. Matesanz’s analysis of its complex geometric patterns suggests that it could serve as a visual representation of a Celtic calendrical cycle lasting 114 years. This timeframe aligns with six Metonic cycles, each spanning 19 years, which is a known astronomical framework that facilitates the alignment of lunar and solar calendars.

The Coligny calendar, an important epigraphic source from France dating back to the 2nd century AD, provides detailed insights into how the Celts structured their time. It organizes time into five-year cycles comprising 62 months, totaling 1,835 days. However, scholars have long debated how these cycles correspond to the tropical year of 365.24 days.

Matesanz’s study is particularly innovative as it establishes a connection between the Coligny calendar and the geometric designs of the Chão de Lamas lunula. He theorizes that the circular motifs on the jewel represent a timekeeping system that adjusts the solar year by eliminating 53 days every 114 years. This intriguing figure of 53 days is also referenced in Irish literary sources, hinting at a potential link to Celtic traditions in Ireland.

Detail of the lunula and nomenclature of the circular motifs present in it. Credit: Piero Baguzzi / R. Matesanz / MAN, Ministerio de Cultura de España
Detail of the lunula and nomenclature of the circular motifs present in it. Credit: Piero Baguzzi / R. Matesanz / MAN, Ministerio de Cultura de España

Geometric Patterns and Celestial Alignments

The lunula’s design is more than decorative; it features large concentric circles and smaller circles with central dots, organized into five distinct sections. Matesanz suggests that these elements may correspond to the months within the Celtic calendar’s five-year cycle.

The arrangement of these geometric motifs is critical. The study indicates that the lunula’s elements could symbolize six five-year cycles, each containing 62 months, culminating in a total of 30 years—referred to as the Celtic saeculum by Pliny the Elder in his Natural History. However, this calculation results in an excess of 53 days compared to the solar cycle.

To address this discrepancy, Matesanz proposes that the Celts would have adjusted their calendar every 114 years by omitting these days, ensuring that their festivals and astronomical observations remained in sync with the changing seasons.

The Coligny calendar. Credit: Wikipedia

Connections to Irish Mythology

One of the most captivating aspects of this research is the appearance of the 53-day figure in Irish Gaelic texts, particularly in the medieval tale Baile in Scáil. In this narrative, the legendary king Conn Cétchathach encounters a magical stone on the Hill of Tara, with his druids stating they cannot reveal his name until 53 days have elapsed. This period of silence may correspond to the days omitted in the Celtic calendar to maintain its alignment with the solar year.

If validated, this hypothesis would indicate that Celtic oral traditions preserved elements of an ancient time synchronization method, even centuries after Roman influence. It would further support the notion that Celtic civilization possessed sophisticated astronomical knowledge, evident in both their artifacts and mythology.

The study also prompts a reevaluation of the role of art as a symbolic language among the Celts. The Chão de Lamas lunula may exemplify how they integrated abstract and mathematical concepts into their artistic expressions.

Additional archaeological discoveries bolster this perspective. In the Iberian Peninsula, similar iconographic objects, such as the Axtroki bowls and the Leiro helmet, suggest potential calendrical functions. Meanwhile, in Central Europe, artifacts like the Schifferstadt-type golden hats have been interpreted as timekeeping instruments, reinforcing the idea of a shared understanding of time across ancient cultures.

Roberto Matesanz Gascón, The lunula with geometric decoration of the treasure of Chão de Lamas and the Celtic calendar. Palaeohispanica, vol.24 (2024). doi.org/10.36707/palaeohispanica.v24i1.543

Cover Image Credit: Piero Baguzzi / R. Matesanz / MAN, Ministerio de Cultura de España

Related Articles

10,000-year-old Settlement Discovered in Turkey’s Şanlıurfa

25 June 2021

25 June 2021

A Neolithic settlement was discovered in the garden of a house in the Sayburç Neighborhood of Şanlıurfa’s Karaköprü district. News...

Europe’s oldest grave of a newborn girl found in İtaly

15 December 2021

15 December 2021

An international team of researchers has found Europe’s oldest tomb of a newborn girl, dating back 10,000 years, in Liguria....

A basement discovered on the premises of the ruins of Hitoyoshi Castle in Japan could be a Jewish bathing facility!

7 December 2022

7 December 2022

Experts are still indecisive about why there was a bathing area in the basement which was discovered on the site...

Medieval ship found off the west coast of Sweden

5 February 2022

5 February 2022

A previously undiscovered wreck has been found outside of Fjällbacka on the Swedish west coast. Analysis of wood samples shows...

A sculpture of a snake-bodied Roman-German deity was discovered in Stuttgart

23 April 2024

23 April 2024

A sculpture of a snake-bodied Roman-German deity was discovered at the Roman fort in Stuttgart, Germany. Since the beginning of...

Archaeologists Discovered One of the Earliest Christian Buildings in Bahrain

14 July 2024

14 July 2024

Archaeologists have uncovered one of the earliest known Christian buildings in the Arabian Gulf, located in Samahij, Bahrain, and providing...

Scientists identified a unique engraving that could be the oldest three-dimensional (3D) map in the world

4 January 2025

4 January 2025

Scientists working in the Ségognole 3 cave, located in the famous sandstone massif south of Paris have identified a unique...

Neanderthals too may have Developed a System of Numerical Notation

2 June 2021

2 June 2021

People developed numbers tens of thousands of years ago, according to archeological findings. Scholars are now investigating the first comprehensive...

A rare medieval Christogram Tattoo from Ghazali, Sudan

22 October 2023

22 October 2023

A Polish-Sudanese research team investigating the medieval African monastery of Ghazali discovered a rare medieval religious tattoo in a tomb...

Klazomenai, ceramic center of ancient period was found the first seal belonging to the city

20 November 2022

20 November 2022

A seal belonging to the city was found for the first time during excavations in the ancient city of Klazomenai...

Unique Two-Faced Gold Ring Unearthed in Poland

10 February 2024

10 February 2024

A gold ring with an unusual two-faced design, likely to be from the 11th or 12th century, has been discovered...

Teacher unearthed stone with ancient ogham writing from Ireland in Coventry garden

9 May 2024

9 May 2024

A geography teacher, Graham Senior, stumbled across a rock with mysterious incisions while tidying his overgrown garden in Coventry, England. ...

Unique Ancient Bronze Miniature Portrait Of Alexander The Great Found In Ringsted On The Island Of Zealand, Denmark

12 April 2024

12 April 2024

Two amateur archaeologists have made a unique find near Ringsted in the Danish island of Zealand. A sign that one...

4,000-year-old cylinder seal found in Blaundos excavations

29 September 2022

29 September 2022

A 4,000-year-old cylinder seal was found during the excavations of the ancient city of Blaundus (or Blaundos, as it is...

INAH Archaeologists recover the coyote-man of Tacámbaro

26 January 2022

26 January 2022

Archaeologists win the coyote-man trial that lasted 30 years in Mexico. The litigation regarding the coyote-man of Tacámbaro, an important...