Leap years are a calendar year that contains an additional day added to keep the calendar year synchronized with the astronomical year or seasonal year. As a result of the Earth’s revolution around the Sun taking approximately 365.242189 days, there needs to be a way to align the seasons and earths rotations. To help keep these things aligned, an insertion of 1 day into the Gregorian calendar, astronomers can correct the drift.

For lunar calendars, leap years take the form of an extra month every few years to correct the mismatch between months and the season of the year. Without these changes, adding an extra month or day, there could the potential for the seasons and month alignment to change over the course of hundreds of years.

When utilizing leap days, there are some very interesting ways to determine when an extra day is added into the Gregorian calendar. This translates to every year that is divisible by 100 does not get a leap day, unless that day is also divisible by 400. This means that the years 1800 and 1900 did NOT get a leap day because they are divisible by 100, but the year 2000 did get a leap day because it is divisible by 100 AND 400.

This differs from leaps seconds, which are not utilized on a regular schedule because variations in the length of the day are not entirely predictable.

Folk traditions

There are a plethora of folk traditions that surround leap years and leap days, many of which surround marriage in some sense.

Finish tradition says that if a woman were to propose on a leap day, and she were to be refused, the person who got proposed to should buy her some fabrics. These fabrics that were purchased are said to be used for a skirt. It is said that many Greek couples will avoid getting married during a Leap Year.

There is the “The Honor Society of Leap Year Day Babies”, for those born on February 29th, which brings up the interesting question of when would the baby celebrate their birthday? Would it be March 1st, since as February 29th is the 60th day of the leap year, normally on a non-leap year, the 60th day would be March 1st?? Let us know what you think!

https://www.timeanddate.com/date/leapyear.html