We need leap years to keep our modern-day Gregorian calendar in alignment with Earth’s revolutions around the Sun.
It takes Earth approximately 365.242189 days, or 365 days, 5 hours, 48 minutes, and 45 seconds, to circle once around the Sun. This cycle is called a tropical year, and astronomers measure this from the March equinox.
However, the Gregorian calendar has only 365 days in a year. If we did not add a leap day on February 29th nearly every four years, we would lose almost six hours off our calendar every single year. After only 100 years, our calendar would be off by around 24 days!
To solve this, we add a leap day on February 29th, every four years.
Roman general Julius Caesar introduced the first leap year over 2000 years ago. However, the Julian calendar had one rule: any year evenly divisible by four would be a leap year. Unfortunately, this formula produced far too many leap years, and it was not corrected until the introduction of the Gregorian calendar more than 1500 years later.
BUT DID YOU KNOW… the Irish came up with a fun tradition that falls on February 29th of a leap year. It is said that the tradition began in 5th century Ireland when St. Brigid of Kildare bitterly complained to St. Patrick that women had to wait far too long for men to propose. The legend says that St. Patrick then decreed that women could propose on this one day in February during the leap year.
The tradition was then taken to Scotland by Irish monks.
In 1288, the Scots passed a law that allowed a woman to propose marriage to the man of their dreams in a leap year. The law also stated that any man who declined the proposal on this day would have to pay a fine. An unmarried Queen Margaret allegedly passed the law and even put in place a rule that each of those women proposing must wear a red petticoat while doing so. Rumor has it Queen Margaret may have only been five years old at the time.