Sunday is Easter Day—for adherents to Western denominations of Christianity. For the Eastern or Orthodox church, which calculates the date using the Julian rather than the Gregorian calendar, Easter falls on May 1st. In some years (such as 2014 and 2017), the dates are the same for both Eastern and Western churches; but they can be as far as five weeks apart. Easter determines the dates of public holidays and school terms, so this can cause confusion in countries where Orthodox and Western Christians rub shoulders. Pope Francis said last year that he was open to change. And in January Justin Welby, the Archbishop of Canterbury, said the Coptic church had proposed fixing the date as the second or third Sunday in April—and revealed that Anglicans had agreed to support this plan. After centuries of effort, Easter’s dates could be aligned in the next few years. Maybe.