Until recently I went about my business believing that a year is 365 days and has 12 months, just as two plus two equals four. But then someone at the reference desk casually wondered aloud why we have leap year, and I immediately had to begin researching calendar history. (I am a self-declared nerd after all). My mind was a bit blown by what I learned.
First, let’s tackle leap year. The solar year, or the amount of time it takes for the earth to make one trip around the sun, is roughly 365.25 days. We have to add an extra day every four years to make up the difference. (Well, we don’t add the extra day during the years that mark an even century, unless they can be divided evenly by 400, but let’s just ignore that fact for simplicity’s sake.) Without this adjustment, the calendar would gradually drift away from the seasons. Your day planner would say that it is spring, but outside it would feel like summer.
So far so good, right? But what if I told you that floating around out there are serious proposals to change the calendar so that every January 1 would be a Sunday, for example? Also, there would be a day at the end of the year not assigned a day of the week or a date on the calendar that we would simply refer to as “Year-End Day.” Or how about carving the year into 13 months of 28 days each instead of 12 months of slightly varying length? Head spinning yet?
While calendars in concept are based on astronomy, the history of the current calendar the western world follows – the Gregorian calendar, named after Pope Gregory XIII – is tangled up in a fascinating web of politics and religion. In “Mapping Time,” E. G. Richards not only recounts the accomplishments of scientists and mathematicians required to establish the Gregorian calendar, but he also describes complicated alternative calendars of various faiths and cultures, as well as other time-tracking mechanisms used throughout history.
Pick up “Mapping Time” at your library, or check out the equally engaging “Calendar: Humanity’s Epic Struggle to Determine a True and Accurate Year” by David Ewing Duncan to learn more about our calendar. What better way to celebrate leap day?