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Pope Gregory XIII.
Pope Gregory XIII chairs the commission for reforming the Julian calendar in 1582.

Painting by G. Dagli Orti, De Agostini/Getty Images

John Roach

for National Geographic News

Published January 17, 2012

Wish you'd had an extra holiday week this year? If a proposed permanent calendar is adopted in the next few years, you'll get one at the end of 2017.

This "leap week" would occur every five or six years under the proposed Hanke-Henry Permanent Calendar.

The occasional extra December week would keep the months in tune with the seasons in a calendar that would otherwise stay the same year after year after year.

Without the addition of the extra week every five or six years, this 364-day calendar on a planet that circles its sun once every 365.2422 days would eventually put Christmas in the middle of the summer due to Earth's seasonal drift.

The periodic addition of an extra week would fix this, said Steve Hanke, an economics professor at The Johns Hopkins University in Baltimore, Maryland.

With the new calendar, Christmas and New Year's Day would always fall on a Sunday; U.S. tax day, April 15, would always fall on Sunday; and the Fourth of July would always fall on a Wednesday.

The calendar is broken up into four quarters, with three months each. The first two months are 30 days and the third is 31 days, adding up to a 91-day period, Four of these 91-day quarters make up a 364-day year of 52 weeks.

"You're getting regularity and even numbers when you are dividing" up the year, said Hanke, who developed the calendar with colleague Richard Conn Henry, a Johns Hopkins astronomer.

That "ends up being very important for things like making contracts; prescriptions for a druggist; interest-rate calculations; and any kind of financial instrument, whether it is a mortgage, a bond, a swap, or a fancy derivative."

(See "Leap Year: How the World Makes Up for Lost Time.")

Leap Week's "Slight Monkey Wrench"

A leap week does throw "a slight monkey wrench" into the financial instruments the proposed calendar aims to fix, said Hanke, who laid out the argument in January in an article in the Indonesian magazine Globe Asia.

That's because that extra week every five to six years may complicate some financial matters, for example a 30-year mortgage.

But those small problems might be easier to deal with than the system of conventions used around the world to account for the imperfect quarters and extra days in the current Gregorian calendar.

For example, to make things easy, the 30/360 convention widely used to set interest payments on bonds and mortgages divides the calendar into 12 even months of 30 days each.

The result, however, is lost revenue, since the world operates with a calendar of 365 days, Hanke noted. The world bond market, for example, misses U.S. $130 billion in interest payments a year. "That's the annual GDP of Hungary or Kuwait," he said.

The permanent calendar would do away with the 30/360 convention but still force accountants to account for the extra week every five or six years.

(See "'Time Cloak' Created; Can Make Events Disappear.")

Calendar Fix Respects Sabbath

Though other strategies have been offered to improve the calendar, Hanke and team's fix is among the few that respects days set aside for religious worship.

Other prominent attempts at calendar reform, such as that of George Eastman of Eastman Kodak fame, would've simplified matters with a calendar of 13 months, each with 28 days. To account for seasonal drift, Eastman proposed the addition of an occasional, unnamed eighth day.

Yet such a proposal doesn't respect a religious day of rest—and thus the reform failed, according to Hanke.

"We've gotten around the problem," he said.

Calendar Reform Lacks Power

Richard McCarty, a philosopher and calendar-reform expert at East Carolina University in Greenville, North Carolina, said the Henry-Hanke Permanent Calendar "makes some sense."

Particularly appealing is the ease of scheduling for businesses and institutions such as universities, where semester start and end dates, for example, change every year, McCarty said.

But he also thinks the proposal "doesn't stand any chance at being adopted."

For one, there isn't much of a demand for calendar reform. The movement lacks eminent leaders such as Julius Caesar, who pushed through the Julian calendar in 46 B.C., and Pope Gregory XIII, who replaced the Julian calendar with our Gregorian calendar in 1582.

"These were very powerful people," McCarty said. "They had the ability to get the rest of the world to go along with them. Nobody has that power now."

But Hanke hopes his proposed calendar will go viral.

"The key thing here is spontaneity," he said. Ideas can randomly catch on "when you are doing science and present ideas."

"Adult Winter Break"

Another key obstacle is what to do with the leap week—or mini-month.

"People will have a hard time figuring out how that month relates to the rest of the months, how that relates in terms of paychecks and rents, and so on. That's going to be a puzzle," East Carolina's McCarty said.

Indeed, there would be a painful adjustment period, but at least everyone would be in the same boat, Hanke pointed out. In addition, the benefits to the economy in the long-term would be well worth the trouble, he said.

His advice? Take the extra week and relax.

"Think about it as an adult winter break—with pay."

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