Trying to avoid doing something?
Set your due date for February 30.
In the Gregorian calendar, as you probably know, all of the months have 30 or 31 days—except February, which has 28 (or 29 in a leap year).
When the Swedish were changing from the Julian calendar to the Gregorian, however, they ended up with a February 30.
Most countries, in making the switch, sacrificed a whole row of days.
The Swedish plan was to make the change gradually, by omitting leap days for 40 years. It was a good plan, if a long one, but ended up being implemented incorrectly because of the Great Northern War.
In 1712 the Swedes decided to just restore the Julian calendar by adding the leap days they had taken out, and they ended up with 28 + 2 days in February.
Several decades later the Swedish converted to the Gregorian calendar in the usual way, by taking out the last 11 days of February 1753.
sourced – Britannica
The tropical year, the time it takes the Earth to go through a complete cycle of seasons, is 365.2422 days long (to four-decimal accuracy).
If every calendar year were 365 days long, then the missing 0.2422 days would add up from year to year, each year starting a little earlier relative to the changing seasons. It would take only 120 years for the calendar to be a month adrift from the season.
Calendar fast facts:
February 31st is exceptionally used on gravestones when the date is unknown, or in at least one case, out of supposed superstition.
May 35th is used in mainland China to avoid censorship when referring to the Tiananmen Square protests of 1989, where the official names are strictly censored by the national government, and the event is normally referred to as June 4th.
December 32nd – The LearAvia Lear Fan aircraft test flight had British government “funding that expired at the end of that year.” After the cancellation of a planned test flight on December 31, 1980, due to technical issues, the first prototype made its maiden flight on January 1, 1981, but the date was officially recorded by sympathetic British government officials as “December 32nd, 1980”.
Non-standard dates used in programming:
In Microsoft Excel, the epoch of the 1900 date format is January 0, 1900. February 31st is used (along with February 32nd and February 33rd) for calculating weather data, and March 0 or 0 March is used often in software engineering.
Oopsies …
In November 2010 it was discovered that a Hanshin Tigers wall calendar incorrectly included the date November 31st. Fans who had bought the calendar were given a sticker to cover up the date, and reprinted calendars were sent.
Just fix it …
Because evening out the months is a part of the rationale for reforming the calendar, some reform calendars, such as the World Calendar and the Hanke–Henry Permanent Calendar, contain a 30-day February. The Symmetry454 calendar assigns 35 days to February, May, August, and November, as well as December in a leap year.
