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An Almost Practical Lunar-Solar Calendar

  • Lunar calendars are notorious for being out of sync with the solar year. This calendar attempts to address this problem by using an annual solar event to determine the beginning of a new lunar year. This recalibrates the calendar automatically and reduces the discrepancy. The mechanism is not without its peculiarities however.
  • The solar year begins on the day of the winter solstice in the Northern Hemisphere at GMT.
  • A lunar month begins on the first day of a new moon at GMT.
  • The solstice and new moons are fixed by scientific observation.
  • The first lunar month of a solar year is the first lunation beginning after the winter solstice.
  • That first month is January (01) in a year with 12 lunations and is Luna (00), an extra "leap month", in a year with 13 lunations.
  • Subsequent months are named familiarly: February (02), March (03), April (04), ... December (12).
  • In years with only 12 lunations, Luna and January are synonymous, somewhat like February 28th and 29th in a Gregorian non-leap year. 
  • This would mean that a person born on the 23rd of Luna and one born on the 23rd of January would some years celebrate their birthdays on the same day and other years a month apart.
  • Since lunar months can arbitrarily differ in length between "hollow" (29 days) and "full" (30 days), the 29th and 30th of any month are also subject to the Gregorian February 28th and 29th treatment.
  • The traditional seven-day week is unaffected by this calendar.
  • There are no intercalary days in this calendar.
  • This calendar might drive accountants nuts by constantly switching between 12 and 13 month years, at least until their software adapted.
  • This is not necessarily a calendar you would want to convert to but if you were already using it, it might not seem all that dysfunctional (unless perhaps you were born on the 30th of Luna).