Egyptian calendar of Kom Ombo temple, in Egypt. Image: Flickr/guillenperez
Forget leap years, months with 28 days and your birthday falling on a different day of the week each year. Researchers at Johns Hopkins University in Maryland say they have a better way to mark time: a new calendar in which every year is identical to the one before.
Their proposed calendar overhaul — largely unprecedented in the 430 years since Pope Gregory XIII instituted the Gregorian calendar we still use today — would divvy out months and weeks so that every calendar date would always fall on the same day of the week. Christmas, for example, would forever come on a Sunday.
"The calendar I'm advocating isn't nearly as accurate" as the Gregorian calendar, said Richard Henry, an astrophysicist at Johns Hopkins who has been pushing for calendar reform for years. "But it's far more convenient."
New versus old
The trouble with designing a nice, regular calendar is that each Earth year is 365.2422 days long, leaving extra snippets of time that don't fit nicely into a cycle of 24-hour days. If this time isn't somehow accounted for, the calendar "drifts" relative to the seasons, and the next thing you know, Christmas Day is coming after the spring thaw.
The Gregorian calendar deals with this by adding an extra day (Leap Day) to February about every four years, correcting for the seasonal drift.
"It's really incredible that in the Middle Ages, they were able to invent a new calendar that was so accurate," Henry told LiveScience. What bothers him about the Gregorian calendar, though, is the frustrating tendency for days of the week to jump around. Because 365 is not a multiple of seven, 7-day weeks don't fit evenly into the Gregorian calendar. That means that each year, dates shift over one day of the week (two during leap years).
"Everybody has to redo their calendars," Henry said. "For sports schedules, for schools, for every damn thing. It's completely unnecessary."
Under the Hanke-Henry Permanent Calendar (named after Henry and Steve Hanke, a Johns Hopkins economist who also advocates calendar overhaul), every date falls on the same day of the week — forever.
The calendar follows a pattern of two 30-day months followed by one 31-day month. That means the old rhyme, "30 days hath September, April, June and November," would need to be revised to "30 days hath September, June, March and December."
To account for extra time, Hanke and Henry drop leap years and instead create a "leap week" at the end of December every five or six years. This extra week, dubbed "Xtr", would adjust for seasonal drift while keeping the 7-day cycle on track.
"The new calendar can be fairly often off as much as three days on the seasons, but looking out, could you tell?" Henry said. "Of course you couldn't tell."
The economics of time
For Henry, the new calendar is worth it because of how much time and effort goes into revising the calendar each year. He first got into the idea of calendar reform while having to yet again update lecture dates and syllabi for his students. He quickly discovered that there were calendar-reform advocates with suggestions on how to do away with that problem, he said.
"My heart sank, and I thought, 'Oh my god, I don't want to get involved in calendar reform. It's the stupidest waste of time. It's hopeless,'" Henry said.