How Cultures use the Moon to Dictate Time

Imagine a place where people track the year not by January snow but by the moon’s phases. Whilst we now have clocks, watches and our phones to tell us how much longer until our lunch break, there was a time when other methods were used. On a remote triangle of volcanic land in the South Pacific, Easter Island (Rapa Nui) once followed a calendar that lived by the moon. Villagers tracked time not by numbered weeks or solar months but by a 30-night lunar cycle, counting each phase as it waxed and waned. 

Easter Island is one of the many islands across the world which has compelling timekeeping evidence from its past (Thomas Griggs)

Human societies have long measured time in wildly different ways. It’s one thing eyeing the sun during the day, but it’s a complete other task trying to dictate time over the course of multiple days. As archaeo-astronomer Anthony Aveni puts it, when early people needed a way to keep time beyond a single day, they looked to a second light in the sky. In most cases it was the moon. Even the Aymara people of the Andes gesture toward their past (ahead of them) and future (behind them), suggesting that our notion of a single, forward-moving clock is not universal.

For tens of thousands of years, the moon was humanity’s first clock. Cave paintings and bone carvings seem to suggest lunar cycles were a big part of it. Some reports suggest that Paleolithic images “dated to at least 40,000 years” often show animals alongside star and moon patterns, hinting at lunar calendars in prehistory. In fact, studies suggest people were using the moon as a calendar 30,000 to 35,000 years ago. 

A time-lapse of the moon shows its lunar phases (Samer Daboul)

By the Mesolithic era (~8000 BCE), a remarkable site in Scotland called Warren Field featured twelve shallow pits aligned to the midwinter sunrise. Archaeologists believe these pits tracked the twelve lunar phases of the year, which would effectively put this as the world’s oldest lunar-calendar monument. The pits line up with the winter solstice sunrise, which in short provided an annual ‘correction’ that synced moon months to the solar seasons. 

On the complete opposite side of the country from Isle of Sky, Warren Field depicts how people may have used pits in the ground to time-keep (Pixabay)

Even hunter-gatherers wanted their lunar months to match the year’s turn of seasons (just as we farm animals and harvest vegetables based on seasonality now). In ancient Egypt, the lunar calendar lived alongside a newer 365-day solar year. This was known  the civil ‘civic calendar’ of the pharaohs. It bore traces of an older lunar reckoning used for agriculture and festivals 

This is a side of the Rongorongo Tablet C, or Mamari (under the Creative Commons Attribution-Share Alike 3.0 Unported license)

The Calendars in the Pacific

On many oceanic islands, the moon remained the focus point to dictate time. For example, Easter Island (Rapa Nui) kept a lunar calendar (known as the Mamari calendar) where months lasted 30 nights, which we know is exactly one lunation. Inscriptions on the famous Mamari rongorongo tablet show 30 crescent glyphs which are “in full agreement with astronomy and other Polynesian calendars”. Early missionaries even recorded being marvelled by the islanders’ detailed knowledge of moon phases. 

There are multiple places around the world which in the past, used the moon to dice various things. In these islands, as in others, every moon phase had meaning for fishing, planting or ceremony. Here are some examples:

• Easter Island (Rapa Nui) – A Polynesian lunar calendar with 30-night months recorded in rongorongo and rock art 

  
  

• Hawaii – Traditional calendar of 12 lunar months (29–30 days each), divided into three 10-day weeks; the new year begins with the first new moon after the Pleiades rise 

  
  

• Banks Islands (Vanuatu) – A lunisolar calendar keyed to ecology: palolo reef worms spawn at a certain lunar quarter, and three special months are timed to these mass spawnings 

  
  

• Samoa – Modern time-twisting: in 2011 the nation skipped Friday, Dec 30, by shifting to the west side of the Date Line, effectively “leaping” a day to align with its neighbours.

The moon was considered the second light to dictate time (Sebastian V.)

The Science of Lunar Timekeeping

Astronomy underlies all these calendars. A single synodic month (new moon to new moon) averages about 29.53 days, so 12 lunar months total (which is actually only about 354 days and about 11 days short of a solar year). Most traditional lunar calendars solved this by alternating 30-day and 29-day months to approximate the moon’s cycle and by adding an extra (intercalary) month every few years (sound familiar?). 

In fact, the ancient Greeks discovered that nineteen solar years almost exactly equal 235 lunar months (the Metonic cycle), an intercalation scheme accurate to within one day in two millennia. Other cultures instead watch the sky directly: for example, Muslims mark the start of each month by sighting the new crescent moon, so the Islamic year shifts through the seasons. Chinese, Hebrew and many Hindu calendars also tie months to specific lunar events (new or full moons) while occasionally inserting months to stay in step with the solar cycle.

In other words, our calendar lengths are cultural choices grafted onto celestial mechanics. One scholarly review notes: “most calendars referred to as ‘lunar’ are in fact lunisolar calendars,” since they must reconcile moon months with the Earth’s orbit. These calendars often grew from farmers’ needs: ancient Egyptians adopted a 365-day year for agriculture but continued a parallel 12-month lunar cycle for planting and festivals. Pacific Islanders managed the same issue by star calendars or by watching nature (like the palolo worm cycles). Even today, scientific studies emphasise that the moon’s regular phases make it a “reliable marker of time”. 

Whilst knowing what time of day it is may not have been important in the routine, it was crucial to know the upcoming seasons for agriculture (Tim Mossholder)

Today, billions still follow calendars tied to the moon: Chinese New Year, Islamic months, Buddhist fasts. They are all lunar or lunisolar. By contrast, the familiar Gregorian calendar is a compromise born from distant history. We inherited month names from Roman gods and saints, and kept the leap-year rule from medieval reformers. However, the rhythms of planting and fishing once depended on the moon and stars.

In the end, the way that traditional timekeeping may still be practiced to this day, reminds us how diverse even a mundane act can be. From Scottish hunter-gatherers to Polynesian navigators, people have shaped calendars around the moon’s phases for eons. In writing this, it is hard not to go so deep as to say that each system reflects a community’s place in the cosmos. As scientist Rebecca Boyle notes, the moon’s changing face has long been “one of humankind’s first timepieces.” In many ways, it still is.