Calendars

Although the Gregorian calendar partially allows for the eccentricity of the earth's orbit and for the dates of perihelion and aphelion, the shortness of February introduces slight inconveniences into daily life. An example is that a person usually pays the same rent for the 28 days of February as is paid for the 31 days of March. Also, the same date falls on different days of the week in different years. These and other examples have led to several suggestions for calendar reform.

Perhaps the best suggestion for a new calendar is the World Calendar, recommended by the Association for World Calendar Reform. This calendar is divided into four equal quarters that are 91 days (13 weeks) long. Each quarter begins on a Sunday on January 1, April 1, July 1, and October 1. These four months are each 31 days long; the remaining eight months all have 30 days. The last day of the year, a World Holiday (W-Day), comes after Saturday December 30 and before January 1 (Sunday) of the next year; it is the 365th day of ordinary years and the 366th day of leap years. The extra day in leap years appears as a second World Holiday (Leap year or L-Day) between Saturday June 30 and Sunday July 1. The Gregorian calendar rules for ordinary, leap, century, and non-century years would remain unchanged for the foreseeable future.

The most recent, and much-discussed, calendrical confusion concerned the so-called Y2K, the rollover of the calendar from 1999 to 2000. Debates ensued as to whether the new millennium would begin on January 1, 2000, or January 1, 2001. Technically, the first day of the new millennium is January 1, 2001, because there was no year zero. The first year of the first millennium A.D.began at the start of the year 1, so the first year of the next two millennia must begin at the start of the years 1001 and 2001. However, a reasonable case can be made that the change of digits to the even year 2000 makes it more significant in human reckoning than the minor change from 2000 to 2001.

A future Mars calendar for the human colonization of Mars in future centuries poses interesting problems. There are about 668.6 sols (mean Martian solar days, which average 24 hours 39 minutes 35.2 seconds of mean solar time long) in a Martian sidereal year. At least one Martian calendar has been suggested, but much more must be done before an official Martian calendar is adopted.