Every four years we have a February 29 – also known as a leap year.
While a relatively minor adjustment for everyone to make, the leap day actually serves a very important role in keeping our seasons in sync with the sun and moon, with a history going back thousands and thousands of years.
They exist because it takes roughly (but not exactly) 365.25 days for Earth to orbit the sun, and so we need to add around one extra day to the calendar every four years.
Over time, leap years have been associated with all sorts of weird and wonderful traditions: from the wild notion that February 29 is the only day when women can propose to men, to the Leap Year Festival held in Anthony, New Mexico, which sees people born on this special day gather to celebrate their rare birthdays together.
In Greece, people believe that getting married on February 29 is unlucky. According to ancient Greek tradition, most marriages celebrated on the leap day will lead to divorce.
Another Greek superstition holds that a couple is destined to never be happy again if they split during a leap year.
Believe these superstitions or not, February 29 is also considered just another normal day for many.