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Hanke-Henry Permanent Calendar

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International 30-30-31 Leap-Week Calendar

The Hanke-Henry Permanent Calendar, devised by Steve H. Hanke and Richard Conn Henry, is a proposed new calendar which aims to reform the current Gregorian Calendar by making every year identical. With the Hanke-Henry Permanent Calendar, every calendar date always falls on the same day of the week. It is basically the same as the Common-Civil-Calendar-and-Time calendar.

History Edit

In 2004, Richard Conn Henry, a professor of astronomy at Johns Hopkins University, proposed the adoption of a calendar known as Common-Civil-Calendar-and-Time, which he described as a modification to a proposal by Robert McClenon. This version had essentially the same structure given above, but inserted its leap week named "Newton" between June and July. The leap rule was chosen to match the ISO week leap rule, to minimize the variation in the start of the year relative to the Gregorian calendar.

He had advocated transition to the calendar on January 1, 2006 as that is a year in which his calendar and the Gregorian calendar begin the year on the same day. After that date passed, he recommended dropping off December 31, 2006 to start in 2007, or dropping December 30 and 31, 2007 to start 2008.[1]

In late 2011 the calendar was revised by Johns Hopkins economist Steve Hanke by moving the leap week from the middle to the end of the year and renaming it "Extra", producing the Hanke-Henry Permanent Calendar. The target date for universal adoption was January 1, 2017 then, but has been postponed to 2018,[2] when the calendar design was changed in early 2016 to adopt Monday as the start of the week, quarter and year, to better comply with existing international standard ISO 8601.

Year layout Edit

January
Week 1 2 3 4 5 6 7
Sun Mon Tue Wed Thu Fri Sat
W1 01 02 03 04 05 06 07
W2 08 09 10 11 12 13 14
W3 15 16 17 18 19 20 21
W4 22 23 24 25 26 27 28
W5 29 30
February
Week 1 2 3 4 5 6 7
Sun Mon Tue Wed Thu Fri Sat
W5 01 02 03 04 05
W6 06 07 08 09 10 11 12
W7 13 14 15 16 17 18 19
W8 20 21 22 23 24 25 26
W9 27 28 29 30
March
Week 1 2 3 4 5 6 7
Sun Mon Tue Wed Thu Fri Sat
W9 01 02 03
W10 04 05 06 07 08 09 10
W11 11 12 13 14 15 16 17
W12 18 19 20 21 22 23 24
W13 25 26 27 28 29 30 31
April
Week 1 2 3 4 5 6 7
Sun Mon Tue Wed Thu Fri Sat
W14 01 02 03 04 05 06 07
W15 08 09 10 11 12 13 14
W16 15 16 17 18 19 20 21
W17 22 23 24 25 26 27 28
W18 29 30
May
Week 1 2 3 4 5 6 7
Sun Mon Tue Wed Thu Fri Sat
W18 01 02 03 04 05
W19 06 07 08 09 10 11 12
W20 13 14 15 16 17 18 19
W21 20 21 22 23 24 25 26
W22 27 28 29 30
June
Week 1 2 3 4 5 6 7
Sun Mon Tue Wed Thu Fri Sat
W22 01 02 03
W23 04 05 06 07 08 09 10
W24 11 12 13 14 15 16 17
W25 18 19 20 21 22 23 24
W26 25 26 27 28 29 30 31
July
Week 1 2 3 4 5 6 7
Sun Mon Tue Wed Thu Fri Sat
W27 01 02 03 04 05 06 07
W28 08 09 10 11 12 13 14
W29 15 16 17 18 19 20 21
W30 22 23 24 25 26 27 28
W31 29 30
August
Week 1 2 3 4 5 6 7
Sun Mon Tue Wed Thu Fri Sat
W31 01 02 03 04 05
W32 06 07 08 09 10 11 12
W33 13 14 15 16 17 18 19
W34 20 21 22 23 24 25 26
W35 27 28 29 30
September
Week 1 2 3 4 5 6 7
Sun Mon Tue Wed Thu Fri Sat
W35 01 02 03
W36 04 05 06 07 08 09 10
W37 11 12 13 14 15 16 17
W38 18 19 20 21 22 23 24
W39 25 26 27 28 29 30 31
October
Week 1 2 3 4 5 6 7
Sun Mon Tue Wed Thu Fri Sat
W40 01 02 03 04 05 06 07
W41 08 09 10 11 12 13 14
W42 15 16 17 18 19 20 21
W43 22 23 24 25 26 27 28
W44 29 30
November
Week 1 2 3 4 5 6 7
Sun Mon Tue Wed Thu Fri Sat
W44 01 02 03 04 05
W45 06 07 08 09 10 11 12
W46 13 14 15 16 17 18 19
W47 20 21 22 23 24 25 26
W48 27 28 29 30
December
Week 1 2 3 4 5 6 7
Sun Mon Tue Wed Thu Fri Sat
W48 01 02 03
W49 04 05 06 07 08 09 10
W50 11 12 13 14 15 16 17
W51 18 19 20 21 22 23 24
W52 25 26 27 28 29 30 31
53 32 33 34 35 36 37 38

Correcting for drift Edit

While many calendar reforms aim to make the calendar more accurate, the Hanke-Henry Permanent Calendar focuses on making the calendar perennial, so that every date falls on the same day of the week, year after year.[3] The familiar drift of weekdays with respect to dates results from the fact that the number of days in a physical year (one full orbit of earth around the sun, approximately 365.24 days) is not a multiple of seven. By reducing common years to 364 days (52 weeks), and adding an extra week every five or six years, the Hanke-Henry Permanent Calendar eliminates weekday drift and synchronizes the calendar year with the seasonal change as the Earth circles the Sun. The extra week, or "mini-month", known as "Xtr (or Extra)",[3] would occur every year that either begins or ends in a Thursday on the corresponding Gregorian calendar.[3] The extra week would fall between the end of December and the beginning of January. Leap weeks in 2015, 2020, 2026, 2032, 2037, 2043, 2048, 2054, 2060 …

Under the Hanke-Henry Permanent Calendar there are two 30 day months followed by one month of 31 days. While the Hanke-Henry Permanent Calendar changes the length of the months, the week and days remain the same.[4]

Advantages Edit

  • Holidays such as Christmas and New Year's Day as well as birthdays always occur on the same day of the week every year.
  • The calendar itself is permanent, it does not change year to year, with the exception of the need to add a week at the end of every 5 or 6 years.
  • Quarters all have the same number of days simplifying financial calculations. This calendar would also have prevented Apple’s Q4 2012 reporting fiasco. [5]
  • Unlike many other reform proposals, it does not change the days of the week.
  • The calendar starts on the same day every year, Sunday, the 1st of January.
  • As in the Gregorian calendar, Sunday to Sunday is always seven days, as is Saturday to Saturday, or Friday to Friday. Because no days are ever added outside a seven-day week, there should be no objection from religious groups concerned about weekly holy days. (In proposals that add single days outside the week, a true "seventh day" of rest or worship would drift between weekends and weekdays.)

Disadvantages Edit

  • Not as precisely aligned with the solar year as the existing Gregorian calendar and some proposed reform calendars.
  • Requires continued use of the Gregorian calendar for certain agricultural purposes.
  • All computer date-handling will have to be fixed, which will be much more complicated than the Y2K fix.
  • US-biased, not compatible with international standards, such as ISO 8601, which start the week on Monday, hence also the week year. This issue could be resolved by modifying the calendar to begin in a year where 1 January falls on a Monday, instead of a Sunday. e.g. Monday, 1 January 2018 instead of Sunday, 1 January 2012.
  • There is no 31st of October, removing Halloween from the current date.

ReferencesEdit

  1. "What if We MISS 2006 January 1 Sunday?"
  2. What is the Hanke-Henry Permanent Calendar?
  3. 3.0 3.1 3.2 "The Hanke-Henry Date and Time, Everywhere in the World"
  4. "Is It Time to Overhaul the Calendar?", by Stephanie Pappas, Scientific American.
  5. [1], GlobeAsia, 2013

External links Edit

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