Why are leap years?

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Every four years an important event happens, added on February 29 to the calendar. As a general rule, years have 365 days, but one day is added every four years. These years with 366 days are called leap years, and we are going to talk about them in today's A PROFESSOR lesson. Let's explain Why are leap years" so that everyone can understand why this strange phenomenon.

A leap year is called a year that has 366 days instead of 365, being the year February ends on the 29th, instead of the 28th. This is because the astronomical year does not correspond exactly to 365 days, but has 365 days, 5 hours, 48 ​​minutes and 56 seconds.

Due to the time difference that exists, what is done is add one day every four years. This is done because each year there is an accumulation of approximately ¼ of an extra day, so that four times this amount would be equivalent to an extra day.

In the Gregorian calendar it is established that leap years are divisible by 4, except for secular years, which are the last day of the year, which must also be divisible by 400.

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Continuing with the lesson of why there are leap years, we must talk about the history of leap years, from when they began to be used, to why we use them today.

The first person who saw problems in the calendar was Julius Caesar. The Roman calendar had centuries of lag due to the imprecision of its methodology. Upon arriving in Egypt, Julius Caesar asked an astronomer named Sosigenes of Alexandria that he would create a calendar for the Romans, a calendar that would be at the same height as the Empire. The Egyptian astronomer was based on the Egyptian calendar, but kept the names of the Roman months. This calendar had 365 days, and another day that was added every four years, something similar to our current calendar.

The problem was that the Roman calendar had a huge lag, due to the imprecision that the Roman calendar had been for many years. So the year 46 a. C. it lasted 445 days, to compensate for the lag. This year was called "the Julian year." The calendar was official in Rome for the next several centuries, until 1582, when the Gregorian calendar was adopted.

The Gregorian calendar is the one currently used in most countries of the world. The calendar made by Sosigenes had a problem, a calculation error in the number of days in a year, so the figure was about 11 minutes from what was due. This miscalculation over more than a thousand years had caused a lag of ten days.

To avoid these problems the current method was created, in which leap years are divisible by 4, except those of the last day of the year that must also be divisible by 400. This method was promoted by Pope Gregory XIII, and that is why it is called the Gregorian calendar.

Leap years are very special dates, there is a huge variety of curiosities around it, and it is interesting to know some of them:

• People born on February 29 they have several curiosities. They usually celebrate their birthday on February 28 or March 1. In Ireland they receive a gift of 100 euros. And in English-speaking countries they are called Leapers, because in English leap year is leap year.
• Three times in history there has been a February 30. One of those times was when Sweden switched from the Julian calendar to the Gregorian, and it had to create this day so that the calendar lag would disappear.
• In England there was a tradition that women could propose to men on February 29. Since the norm of the time was that men had to ask for marriage.
• In Greece, getting married on a leap year is considered bad luck. This also happens in other countries, as leap years have been seen as unlucky days by many civilizations.

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