We take our timekeeping rules for granted, but the history of these rules is long and complex.
We have divided time into units to make sense of its passage over a large portion of human history. Although this has been done in many ways by different civilizations, the most popular method nowadays is to divide time into seconds, minutes, hours, days, weeks, and years.
However, what is the number of weeks in a year?
A normal year typically consists of 52 weeks plus one extra day. There are 52 weeks and two extra days in a leap year, which happens nearly every four years.
When did we decide that a year has fifty-two weeks?
It’s a complicated narrative of how we came up with these timekeeping guidelines. The earliest known timekeeping techniques extend back 11,000 years. An Aboriginal stone arrangement in Australia implies that its builders tracked the passage of time by using the sun’s patterns.
According to Demetrios Matsakis, the head scientist at Masterclock, Inc. and a former chief scientist at the US Naval Observatory’s Department of Time Services, “the biggest driver [for keeping time] was probably religion,” he told Live Science. Certain prayers had to be recited by the Sumerians, Egyptians, and others at specific times of the day and night.
Since then, societies have used the sun’s and moon’s positions to record the passage of time. Some calendars have tried to blend the two, while others have been based just on the sun or the moon.
Because of the interaction between the Earth’s and the sun’s gravitational fields, the moon’s orbit is highly erratic, making the sun a far better tool for measuring time,” Matsakis stated.
The most widely used calendar in the world, the Gregorian calendar, is a solar calendar that is solely based on how the Earth orbits the sun. It comes from the calendar that Julius Caesar established in 46 B.C. The Julian calendar added one day every four years because it determined that the year had 365.25 days. But in reality, there are 365.2422 days in a year. About eleven minutes were overlooked by the Julian calendar, which grew worse over time.
About ten more days had been added to the calendar by the time the disparity was discovered in the 1600s. The Catholic Church got concerned about this since it wanted to maintain an accurate calendar in order to observe holidays correctly.
Pope Gregory XIII was concerned that Easter was being observed at the incorrect time because of the cumulative effect of that disparity throughout the ages, according to Matsakis. The church faced more challenges when other holidays were celebrated based on how far away they were from Easter.
The pope decided that any centurial year that is not divisible by 400 shall have leap years skipped in order to solve the issue. Gregory decided that in order to make up for the extra days caused by the minor error in the Julian calendar, October 4, 1582, would skip straight to October 15.
The new calendar was swiftly adopted by some nations but not by others. Some, like England, declined for religious grounds; the country’s Protestantism ran counter to Catholic Church decrees. It was not until 1752 that the United Kingdom adopted the new system. Alternative calendrical systems had long been noted by others. For instance, China did not switch to the Gregorian calendar until 1912, having previously utilized a lunar calendar. It wasn’t until 1929 that the nation began to use it extensively.
In order to prevent misunderstanding, many papers in the years after Pope Gregory’s edict listed both Old Style dates, which reflected the Julian calendar, and New Style dates, which reflected the Gregorian calendar.
The calendar was later improved upon to surpass the Gregorian in accuracy. According to Matsakis, the leap year system was altered once more in 1923 at the suggestion of Serbian astronomer Milutin Milanković.
With the exception of those that left remainders of 200 or 600 when divided by 900, no year that was not divisible by 100 was considered a leap year this time. Up until 2800, the Milanković calendar will coincide with the Gregorian calendar. Only specific Eastern Orthodox Church branches have embraced it, despite the improved accuracy.