Definition of Leap Year

The year 2012 or 2016 are leap years. This means that in both years there are a total of 366 days and not the usual 365 days. The variation of one day in leap years is reflected in the calendar on a specific day, February 29. Obviously, this change in the total number of days has a reasonable explanation.

What is a leap year and why do they exist?

To understand this peculiarity of the calendar, it must be remembered that the Earth moves around the Sun and the complete orbit takes place in 365 days and 6 hours. This figure makes a year last 365 days, but there is the problem of 6 hours left. So that the time that affects the movement of the Earth around the Sun, and the calendar time coincide, the leap year was created.

In this way, every 4 years there is a leap year (3 successive years with 365 days and on the fourth the missing hours are recovered and the year has 366 days). If a full day were not added every four years, the seasons would be out of phase by relationship with the calendar, in such a way that after 700 years in the northern hemisphere Christmas would fall in

summer and the opposite would happen in the southern hemisphere.

The origin of our calendar

Primitive peoples used the phases of the Moon as a calendar. This idea was rejected when the Egyptians discovered that lunar calendars were not used to predict the start of the annual floods of the River Nile. This was because the phases of the Moon are very short and cause errors more easily.

On the other hand, the Egyptians realized that by following the movement of the Sun they could predict the seasons and, in addition, every 365 days the longest day of the year arrived. Since then the Egyptians began to use the solar calendar. Is conception of the Egyptians it was incorporated by the Romans. It was Emperor Julius Caesar who definitively renewed the calendar and introduced the concept of a leap year. This happened in the 1st century BC. C, because previously the Romans had an annual calendar of 10 months.

The calendar that Julius Caesar introduced is known as the Julian calendar, which was reformed in the seventeenth century by the initiative of Pope Gregory XIII and for this reason it is known as the Gregorian calendar. The Gregorian calendar introduced a modification relative to leap years and the new rule incorporated some exceptions to criterion general leap years (this adjustment was based on new knowledge about the translation of the Earth around the Sun).

Photos: iStock - ineskoleva / LevKing

Leap Year Themes