Enter leap day and leap year, with a 29th day added to February every four years to straighten things out. Well, sort of, but ...

The origin of the leap year, which adds one day—the 29th—to the end of February once every four years, dates all the way back to 46 B.C. An astronomer named Sosigenes of Alexandria told Julius ...

every four year phenom that adds a 29th day to February. The math is mind-boggling in a layperson sort of way and down to fractions of days and minutes. There’s even a leap second occasionally ...