Jamie Carter observes how dependent religious events such as Easter are on the moon. Humans celebrate these events not because of a numbered calendar date, but because of lunar cycles.

When is Easter? That’s easy—Easter is on Sunday, April 12, 2020 for western christians and on Sunday, April 19, 2020 for eastern orthodox christians.

Two dates, forever changing—Easter does not have a specific date.

Unlike Christmas Day, it changes every year depending on something that most people don’t often associate with the christian religion—the moon.

For the world’s 1.8 billion muslims, the exact date of Ramadan is determined by the lunar cycle—with the physical sighting of the crescent moon the day after a New Moon the critical factor. In 2020, that’s Thursday, 23 April—the evening after the next New Moon—unless the crescent isn’t sighted, in which case it will begin the evening after when the New Moon is higher in the post-sunset sky…

Easter is celebrated by roman catholics and protestant christians on the first Sunday after the first full moon occurring on or after the vernal equinox as determined by the Gregorian calendar. That’s the rule. Since the equinox occurred on March 20, 2020 and the “Super Pink Moon” appeared on April 7, 2020, so the date of Easter Sunday was automatically set for Sunday, April 12, 2020. It’s been that way since the year 325 A.D…

Although its 99% a lunar festival in terms of the date it’s held, Easter isn’t just determined by the moon’s phases. The ecclesiastical authorities fix the vernal equinox at March 21, thereby limiting the dates when Easter can occur…

Clocks are a modern invention, as is the convention of global calendars standard time. “Prior to the Gregorian calendar, which is our standard calendar now, calendars were set by the phases of the moon because we didn’t have clocks,” said Dr. Jackie Faherty, Senior Scientist and Senior Education Manager jointly in the Department of Astrophysics and the Department of Education at the American Museum of Natural History.

The Gregorian calendar is a solar calendar that evolved from a lunar calendar. “Standards of time only began when people wanted to set train timetables, and this idea that we have a universal time that we can all get from looking at our watch is something we take for granted,” said Faherty…

Much of our calendar comes from astronomy,” said Faherty, stating that Monday is named after the Moon. “It’s a constant and observable feature that you can get your own understanding of, with its changing phases a great way of tracking the seasons.”

Our concepts of time, and the language we use to talk about it, owe a lot to the Moon and the Sun.“There’s so much to our keeping track of our time that’s related to astronomy, and so much in the early days was set and understood by the Moon—so that was the way that many religious calendars were calculated, and still are today,” said Faherty.

Carter, J. 2020. ‘When Is Easter? The Lunar Festival That’s Determined By The Movements Of The Moon.’ Forbes. April 9, 2020. https://www.forbes.com/sites/jamiecartereurope/2020/04/09/when-is-easter-the-lunar-festival-thats-all-about-the-movements-of-the-moon/#4c8acf3316d7


Joshua Keating reports that not all territories have always been interested in adopting a standardised social time. The U.S. national time is provided as an example of this, in which the railroad network demanded a country-wide common clock, despite cities such as Cincinnati wanting to remain with a more natural time.

We measure time not simply in terms of minutes and seconds, but in terms of concepts such as “early,” “late” – or, for that matter, “fashionably late.” What is the length of a “work day”? In the United States, Europe and Japan you’ll get three different answers.

Those subjective views help explain why the standardization of time has often been met with reluctance, if not outright resistance. Historically, countries have not eagerly embraced the global clock—they’ve felt compelled to do so because of the demands of commerce.

The U.S. national time standard, for instance, didn’t emerge until 1883, when it was adopted by the railroads, which needed to maintain common timetables. Before that, cities largely kept their own local time, and many were not happy to have big government and big railroads force standardization on them. “Let the people of Cincinnati stick to the truth as it is written by the sun, moon and stars,” editorialized one newspaper when the changeover was going into effect (Keating 2013).

Keating, Joshua. 2013. “Why time is a social construct.” Smithsonian.com. January 2013. https://www.smithsonianmag.com/science-nature/why-time-is-a-social-construct-16 4139110/


Robert Coolman traces the historical division of time into minutes and seconds to ancient forms of calculation, as well as to later improvements in the measurement of activity in the sky. The distinction is raised between the constancy of visible celestial movements, versus the technological contingencies underpinning the developing representations of such movements.

For millennia, ancient civilizations looked to the sky to measure the big units of time. There’s the year, which is the time it takes Earth to complete one orbit around the sun; the month, which is approximately how long it takes the moon to orbit our planet; the week, which is approximately the time between the four phases of the moon; and the day, which is the duration of one rotation of the Earth’s on its axis. Dividing the day was not so straightforward, though hours and minutes have their origins in traditions tracing back thousands of years…The use of 60 began with the Sumerians who used different number systems. While you and I write numbers using base 10, or “decimal” this civilization used base 12 (“duodecimal”) and base 60 (“sexigesimal”)…Medieval astronomers were first to apply sexigesimal values to time. The 11th-century Persian scholar Al-Bīrūnī tabulated times of new moons on specific dates in hours, 60ths (minutes), 60ths of 60ths (seconds)…Minutes and seconds, however, were not used for everyday timekeeping for several centuries. Mechanical clocks first appeared in Europe during the late 14th century, but with only one hand, following the design of sundials and water clocks…astronomers of the 16th century began physically realizing minutes and seconds with the construction of improved clocks with minute and second hands in order to improve measurements of the sky (Coolman 2014).

Coolman, Robert. 2014. “Keeping time: Why 60 minutes.” Live science. April 19 2014.  https://www.livescience.com/44964-why-60-minutes-in-an-hour.html


Kevin Birth argues that the human knowledge of time is not associated with celestial movements. Instead, the knowledge that humans have of time is embedded within culturally diversified objects and tools, which distantly represent celestial movements.

The study of objects of time is the study of cognition and culture, but not of the sort limited to the mind or to a simpleminded notion of cultural boundaries. For most clock users, the logics used to determine the time are outside of their knowledge but within the objects. These logics have an artifactual existence that mediates between consciousness and the world—part of what Cole describes as the “special characteristics of human mental life” as “the characteristics of an organism that can inhabit, transform, and recreate an artifact-mediated world” (1995, 32). When one wants to know what time it is, one does not calculate it, but simply refers to a clock or watch. When one wants to know the date, one consults a calendar rather than observes the Sun, Moon, and stars. This placement of temporal logics in artifacts clearly forms a feature of humans that is quite different from anything shared with any other animal—not only do humans make tools, and not only do humans have knowledge far beyond what animals exhibit, but humans place this knowledge in tools. The cultural diversity of concepts of time is closely related to the fusion of diverse ideas and artifacts used to think. Whereas my examples so far are the clock and the calendar, the use of objects to mediate time is not new. Objects related to time are among some of the most famous in the archaeological record, for example, Stonehenge, the Aztec calendar, and the Antikythera Mechanism (Birth 2012, 9).

Birth, Kevin. 2012. Objects of time: How things shape temporality. New York: Palgrave MacMillan.


Robin Parry notes that whilst the eternity of God transcends the natural temporality of the created world, natural time governs the seasons. Seasons in the Torah refer to religious and sacred festivals. In this impression, natural rhythms, including the periodic emergence of the full moon, are believed to regulate the temporalities of collective rituals.

The cultic association of the sun, moon, and stars – that they are the lamps in God’s cosmic temple – brings attention to a central focus of the author: “Let them be for signs (otot) and for seasons (mô’adîm), and for days and years.” The word translated here as seasons (mô’adîm) is always used in the Torah to refer to religious festivals, sacred seasons, and not merely the natural seasons of the year. The sun and the moon are given important assignments vis-à-vis Israel’s cultic festivals. It may be that the sun and moon are assigned roles over two kinds of time: sacred time (signs and festivals) and ordinary time (days and years).

With regard to natural time we may note that the stars were used to predict the seasons. They were also used to tell the time at night (when sun dials are not much help) and allowed an accurate prediction of when sunrise would happen. So they functioned somewhat akin to calendars and clocks.

With regard to sacred time we should note that ancient Israel used a lunar calendar and that its “appointed festivals” (mô’adîm) were regulated by this calendar. Thus Passover, Unleavened Bread, and Tabernacles all occur on a full moon. The “new moon” (hodes), the first day of the month, was also celebrated as a religious festival. What is fascinating about the creation of the sun, moon, and stars in Genesis 1 is that part of the reason that God made them was to regulate the rhythms of Israel’s worship – natural time and sacred time were linked (Parry 2014, 114-15).

Parry, Robin. 2014. The biblical cosmos: A pilgrim’s guide to the weird and wonderful world of the bible. Eugene: Cascade Books.