What is leap year? When does it occur? These are some of the most questions asked about the leap year. Let’s learn more about it, and why does it occur.
The Gregorian calendar, the calendar used by most countries, has 365 days. But every 4 years, we have a year that have 366 days.
Why does it exist?
It takes Earth more than 365 days to complete an orbit around the sun. To be exactly, it takes 365 days 5 hours 48 minutes and 56 seconds. So, every year, the calendar year is getting behind the time to take Earth to complete the orbit. If we didn’t account, somehow, this difference, the seasons would begin to drift, starting earlier each year. This would keep happening and after 700 years summers, that start in June in the northern hemisphere, would then start in December. Same thing for the southern hemisphere. Summers, that start in December, would then start in June.
So what do we do? We have a difference of almost 6 hours every year between the complete orbit and the calendar year. So we add a day every 4 years to adjust our calendar.
It’s believed that February was chosen because it was the shortest month.
But there’s a little problem: 5 hours 48 minutes and 56 seconds is not 6 hours. So, when we add an extra day to the calendar every 4 years, we are actually adding a day of 23 hours 15 minutes and 44 seconds. This way, we are actually putting our calendar a little ahead of the time to complete the orbit. If we left this way, seasons would start to drift again overtime. For this reason, not every 4 years is a leap day.
It was decided that all years that finish in 00 (two zeros) wouldn’t be a leap year unless the number is divisible by 400. So, year 2000 was a leap year, but years 1800 and 1900 were not. The next time we are going to skip a leap year will be in 2100.
Why is it called leap year?
A regular 365 days year is 52 weeks and 1 day. So, for example, if June 1st is on a Tuesday this year, next year it will be on a Wednesday. Unless next year is a leap year. In this case, it will be on a Thursday, skipping 2 days. This happens to every date from March 1st of the leap year, to February 28 of the following year.
Folk Traditions
Britain and Ireland
It’s a tradition in Britain and Ireland that women may propose marriage only in leap years.
These are some funny 1908 postcards showing this tradition:
Finland
If a man refuses a woman’s proposal on leap day, he must buy her fabric for a skirt.
France
Since 1980 a satirical newspaper La Bougie du Sapeur is published only on leap year, on February 29.
Greece
Marriage in a leap year is considere unlucky. One in five engaged couples will avoid getting married in a leap year.
United States
The town of Anthony, in New Mexico, declared itself the Leap Year Capital of the World. Every four years, people who were born on February 29th gather in the town to celebrate their birthday. People from all over the world have come to the celebrations.
Scotland
It’s believed in Scotland that leap days are a bad year for livestock, specially sheep.