Leap Year 2024: Why an Extra Day Is Needed Every 4 Years

Every four years, the calendar adds an extra day at the end of February to adjust the calendar with the seasons of the earth, especially to make sure that the summer solstice in the northern hemisphere and the winter solstice in the southern stay relatively close to its calendar window.

Leap years happen every four years, except every 100 years, unless the year is divisible by 400. This means that there would be a leap year in the year 2400 in the next century.

The next leap year would be in 2028.

Since February 29 is a day that only exists every four years, people and businesses celebrate it differently. For businesses, there are several deals that would come specifically for the day.

History, Importance of Leap Day

The primary reason for using leap days every four years is because of the Earth's orbit.

According to the National Air and Space Museum, the amount of days it takes for Earth to complete a full revolution around the Sun is actually 365.242190 days, which means there is approximately a quarter of a day deficit in the Earth's orbit every year.

The leap day every four years would allow the seasons to correctly line up each year. If leap day were left off the calendar, the months during which each season is normally experienced would eventually shift. This would also impact other aspects of life, such as the growing and harvesting of crops.

The concept of a leap day is not new, as the Hebrew, Chinese, and Buddhist calendars contain leap months, also known as intercalary or interstitial months.

During the Roman period, Julius Caesar got the idea of leap days from the Egyptians, who had been following a solar calendar of 365 days with a leap year every four years.

The Roman calendar varied and included a 23-day intercalary month called "Mercedonius," which was added to February to account for the difference between the Roman and the solar year.

The Roman Empire officially adopted the Julian calendar on Jan. 1, 45 BC.

While the method would stand the test of time, Caesar's math of 365.25 days was close but not exact, which meant that he overestimated the solar year by 11 minutes and that the Julian calendar would be short a day every 128 years.

By the 16th century, scientists under Pope Gregory XIII noticed that time had shifted again as major Christian holidays changed, including Easter, which is supposed to occur on the first Sunday following the first full moon on or after the spring equinox.

To fix this, Gregory introduced the Gregorian calendar, which kept a leap day every four years but eliminated it during centurial years, not divisible by 400.

Despite its accuracy, the Gregorian calendar is not flawless. Instead of being off by one day every 128 years like the Julian calendar, the Gregorian calendar falls short once every 3,030 years.

(Photo: Google)

Frog Used in Leap Day Google Doodle

To celebrate the occasion, Google has marked Leap Day with a special Google Doodle of a frog adorned with the date 29 to symbolize the day. The animated depiction shows the frog leaping from one end of a pond to another, with the date vanishing as it jumps, all set against a serene backdrop of stones and leaves.

"Ribbiting news, it's Leap Day!" Google's caption read. "Leap Day, February 29th, only occurs about every four years, to keep our calendars in alignment with the Earth and sun... Enjoy this bonus day of February - Happy Leap Day!"

In addition to celebrating Leap Day, Google took the opportunity to share insights into the history of its iconic doodles, the Economic Times reported.