Monks who failed to factor in the leap day placed spring equinox on the wrong day, which meant Ash Wednesday, Lent, Holy Week and Pentecost were also marked on the wrong day.
Some time measurements, like months and years, use the movements of the moon and sun, respectively. But other time measurements, like the hour, aren’t clearly connected to astronomical phenomena.
School districts throughout the nation are beginning to heed calls to give students and teachers a day off in observance of the Eid al Fitr, a major Islamic holiday held at the end of Ramadan.
Leap years were devised in Julius Caesar’s time, to fix the pesky problem that Earth’s year isn’t exactly 365 days. But 15 centuries later, our calendars were still slightly askew.