Leap Day is a Good Time to Look How the Sun, Moon and Earth Mark Time

Today is February 29th. It comes in our Western-World-invented calendar every four years. Why we have to insert this extra day every four years is an error correction activity to align the year marked by Earth’s annual cycle around the Sun with our months which roughly correspond to the changing appearance of the Moon, each marked by seven days approximating one-quarter phase. We don’t think about how much we are governed in our lives by the cycles we observe on our planet and in neighbouring space.

The Egyptians and the civilizations of Mesopotamia were the first in the Western half of the world to document time by the movement of the Moon, Earth, and Sun. They created a 12-month year. In China, similar calculations led to a similar conclusion. Lunar calendars were given intercalary extra months to align them with the solar year.

The Julian calendar based on Earth’s annual orbit around the Sun was adopted by the Romans. It superseded the lunar calendars of older cultures. Eventually, the Julian went through a realignment to become the Gregorian calendar which was adopted in Europe in 1582. Russia stuck with the Julian calendar until recently. China adopted the Gregorian calendar in 1912 although it still observes the lunar calendar traditions.

Where Islam is the predominant religion, the lunar calendar remains how people mark time. The Islamic or Hijri calendar consists of 12 months of 29 or 30 days. It does not insert intercalary months which means that observed holidays and festivals change from year to year. I have often felt for Muslim friends when the daytime fasting month of Ramadan falls in the Northern Hemisphere when days marked by sunrise and sunset are long.

In the past, there was at least one effort to reconcile the calendar more logically than the nursery rhyme:

Thirty days hath September,
April, June and November;
All the rest have thirty-one,
Excepting February alone.
Which only has but twenty-eight days clear
And twenty-nine in each leap year.

The most notable alternate dating system was adopted in 1793 by the French revolutionary government based on a more rational and scientific system not dependent on Christian religious practice. The new 12-month calendar set the start date to coincide with the Gregorian calendar’s October 5th, 1793. It marked Year 1 in the new month of Vendémiaire. Each of the newly named months was 30 days. Instead of weeks, the French adopted three 10-day décades per month. The year-end included five or six supplementary days, the latter to account for the extra Leap Day.

We are tied to celestial timekeepers with their roots determined by observations that go way back in time.

The Sun’s daily cycle marks the progression of day to night. Our first clocks were sundials.

Our 7-day weeks correspond to the phases of the moon from new to waxing crescent to full to waning crescent.

Our Earth’s rotation marks the days which are based on ancient Mesopotamian, actually Sumerian, observations that used the number 6 to divide a year lasting 360 days into 12, 30-day segments. This sexagesimal system produced how we mark time with 60 seconds in a minute, 60 minutes in an hour, and 4 six-hour segments to mark the passing of each day. Our clocks and watches to this day are all 6-based.