Google celebrates Leap Day, on the 29th day of February, which only happens every four years, to keep our calendars in alignment with the Earth and the sun.

A leap year occurs approximately every four years, when an extra day is added to the Gregorian calendar, making the total length of that year 366, not 365, days.

Leap years occur due to “a mismatch between the calendar year and the Earth’s orbit. While we think of a year as 365 days long, it actually takes a little longer for the Earth to revolve around the sun.

That extra quarter of a day has to go somewhere, so about every four years, we add 24 hours—or four times six hours—to the calendar. the mismatch between human calendars and the orbit of the Earth and the sun caused “chaos” for centuries until Pope Gregory 13 implemented the Gregorian calendar and its leap year.

Babies born on February 29th can simply choose to celebrate their birthday on March 1st.