We can thank Julius Caesar and the Greek astronomer, Sosigenes of Alexandria, for creating February 29. It takes 365.2422 days for Earth to orbit the Sun, and calendars need to be synchronized to account for that extra fraction of a day. Before the Julian calendar was introduced in 46 BC, the Roman calendar was observed, consisting of 355 days and an extra 22- day month occurring every two years. Julius Caesar ordered Sosigenes to improve the calendar, which became a 365- day year with an extra day every four years to account for the extra hours. Since February was the last month in the Roman calendar, it made sense to add the extra day in February in the Julian calendars.