A US physicist is lobbying for people to adopt his novel calendar in which every date falls on the same day of the week each year.

The current calendar, which runs for 365 days, was instituted by Pope Gregory in 1582 to bring the length of the year in line with the seasons. But because the Earth actually orbits the Sun every 365.24 days, a 366-day “leap year” must be added every four years to account for the extra fraction of a day. In this Gregorian system, a given date (such as New Year’s Day) falls on different days of the week in different years because 365 is not evenly divisible by seven.



That means new calendars must be printed every year, and the dates for recurring events constantly recalculated. “For many years, I’ve had to make up a new schedule to tell my class when homework is due,” says Dick Henry, a physicist at Johns Hopkins University in Baltimore, Maryland, US. “Here I am putting all this totally unnecessary work in and I decided I better do something about it.”



So Henry designed a calendar that uses 364 days, which breaks down evenly into 52 weeks. In his so called “Calendar-and-Time” (C&T) plan, each month contains 30 or 31 days. He decided on each month’s length by forbidding the new calendar to differ from the old one by more than five days and by setting Christmas Day, 25 December, to always fall on a Sunday.



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