We once used to embrace a 13-month calendar, and some cultures still follow this format. So why are they 12 months instead of 13?

As Iranians celebrate the Persian New Year, explore the fascinating calendars still used around the world—shaped by sun, moon ...

Today is April Fools’ Day, the annual holiday that celebrates pranking, hoaxes, and all manner of horseplay and tomfoolery.

For example, the Julian date for December 11, 1942 is 2430705; while December 12, 1942 is 2430706 ... date," which is the common calendar notation of month, day and year. THIS DEFINITION IS ...