What is a leap year? Why this February has a bonus day

The date, Feb. 29, 2024, may seem like an error to some, as the second month usually only has 28 days, but since it is a leap year, February will, in fact, have 29 days.

A leap year usually occurs every four years, as calendars take into account an orbit around the Sun taking more than 365 days to complete. In fact, according to NASA, Earth takes 365 days, 5 hours, 48 minutes and 46 seconds to complete an orbit around the star.

Those extra hours, minutes and seconds beyond day 365 constitute the extra time that is added to a leap year.

If an extra day was not occasionally added to a year, seasons would begin to fall forward, and in several hundred years, a North American winter would happen during what is currently summer and vice versa.


The history behind leap years

Julius Caesar, in 45 BC, is long credited for beginning the practice of adding an extra day to the calendar year.

According to the Astronomy Program at Francis Marion University, Ceasar’s program worked well for hundreds of years, but those extra days added up.


The Earth's orbit around the sun gives our planet its four seasons. (Credit: NOAA)

A new calendar system was employed by Pope Gregory XIII in the 1500s and essentially kept a leap year every four years, with one exception- if the year ended in 00 and wasn’t divisible by 400.

The Gregorian calendar continues to be used by much of the modern world today, and because the years 1700, 1800, and 1900 were not divisible by 400, they were not considered to be leap years.

Using the Gregorian calendar system, the next year that is slated to be a leap year but won’t be because of divisional powers is the year 2100.

RELATED: What are 'leaplings?': How birthdays work on leap day

The years 2024, 2028, 2032, 2036, and so on will have 29 days in February, which makes the month longer than is typical, but the second month will still remain the shortest of the year.


Birthdays on leap days

Millions of people share the birthday of Feb. 29, meaning they only experience their actual birthdate once every four years.

The odds of actually having a birthdate on Feb. 29 are 1 out of 1,461.


Red circle mark on February 29th day on calendar. (Credit: Getty Creative)

Instead of waiting every four years to celebrate being older, many leapings choose to have their birthday before February is out.

Several countries have laws that help determine when a person on Feb. 29 officially turns a year older.

Those who live in the United Kingdom observe leap year birthdays on March 1, while those in the U.S. observe the date on Feb. 28.

Several support groups, including the Honor Society of Leap Year Day Babies, have grown throughout the years and are described as a place where those who share the same birthdays can connect and share experiences.

Find more updates on this story at FOXWeather.com.