Gregorian Leap Day · Ruz-e Kabiseh-ye Miladi

Culture of origin: International · International

Holiday sources: Iran

February 29, the leap day, is added to the Gregorian calendar to keep it in line with the seasons as the Earth orbits the Sun. It comes in years divisible by four, except century years not divisible by 400: 1700, 1800 and 1900 had no leap day, while 1600 and 2000 did. Until the 16th century the extra day was made by doubling February 24, a practice dating from Julius Caesar's calendar edict of 45 BCE.