Why are there leap years and how did they come about?

We just entered 2024, an exceptional year for being a leap year. But what makes a leap year special? And why do we need these extended years? Let’s explore the meaning behind this phenomenon and its intriguing history.

Leap years, with their 366 days, occur every four years in the Gregorian calendar, used by most of the world. The addition of this extra day, called leap day, is February 29th, non-existent in non-years. leap years.

Years divisible by four, such as 2020 and 2024, are leap years, except centennial years not divisible by 400, such as 1900.

Leap years: a ‘leap’ in time?

Image: Shutterstock/Ivelin Radkov

The term ‘leap’ refers to the fact that, starting in March, each date advances one day from the previous year. For example: March 1, 2023, a Wednesday, will be a Friday in 2024. This peculiarity does not occur in common years.

Several calendarslike Hebrew, Islamic, Chinese and Ethiopian, also have versions of leap years, but with variations in their periodicity.

In addition to leap years and days, the Gregorian calendar includes leap seconds, eliminated from 2035 by the IBWM.

Although it may seem like a curiosity, leap years play a crucial role. The discrepancy between the calendar year (365 days) and the solar year (approximately 365.24 days) would result in significant changes over time.

Without leap years, in 700 years, summer in North hemisphere it would start in December, misaligning the seasons.

Adding leap days every four years makes up for this difference, bringing it closer to the solar orbit. However, the system is not perfect, generating a surplus of 44 minutes every four years.

To correct, we skip leap years in centennial years, except those divisible by 400, such as 1600 and 2000.

The concept of leap years dates back to 45 BC, when Julius Caesar introduced the Julian calendar. This, with regular leap years, synchronized with the seasons through adjustments, such as the last year of confusion in 46 B.C.

In the 16th century astronomers noticed deviations in the Julian calendar. In 1582, Pope Gregory XIII reformulated it, giving rise to the Gregorian calendar, adopted by Catholic and, later, Protestant countries.

The transition of calendars caused time jumps, exemplified by Great Britain in 1752. Despite its effectiveness, the Gregorian calendar may eventually need reevaluation, but this adjustment will be required over thousands of years.

The history of leap years reveals the search for harmony between civil and celestial time.