DON’T FORGET THIS FEBRAURY HAS 29 DAYS.. WHY?
February 29, known as a leap day in the Gregorian calendar, is a date that occurs in most years that are evenly divisible by 4, such as 2004, 2008, 2012 and 2016. Years that are evenly divisible by 100 do not contain a leap day, with the exception of years that are evenly divisible by 400, which do contain a leap day; thus 1900 did not contain a leap day while 2000 did. Years containing a leap day are called leap years. February 29 is the 60th day of the Gregorian calendar in such a year, with 306 days remaining until the end of that year.
LEAP YEAR EXPLAINED:
Although most years of the modern calendar have 365 days, a complete revolution around the sun takes approximately 365 days and 6 hours. Every four years, during which an extra 24 hours have accumulated, one extra day is added to keep the count coordinated with the sun’s apparent position.
It is, however, slightly inaccurate to calculate an additional 6 hours each year. A better approximation, derived from the Alfonsine tables, is that the Earth takes a complete revolution around the sun in 365 days, 5 hours, 49 minutes, and 16 seconds. To compensate for the difference, an end-of-century year is not a leap year unless it is also exactly divisible by 400. This means that the years 1600 and 2000 were leap years, as will be 2400 and 2800, but the years 1700, 1800 and 1900 were not, nor will be 2100, 2200 and 2300.
The Gregorian calendar repeats itself every 400 years, which is exactly 20,871 weeks including 97 leap days. Over this period, February 29 falls 13 times on a Sunday, Tuesday, or Thursday; 14 times on a Friday or Saturday; and 15 times on a Monday or Wednesday.
The concepts of the leap year and leap day are distinct from the leap second, which results from changes in the Earth’s rotational speed.
The leap day was introduced as part of the Julian reform. The day following the Terminalia (February 23) was doubled, forming the “bis sextum“—literally ‘double sixth’, since February 24 was ‘the sixth day before the Kalends of March’ using Roman inclusive counting (March 1 was the ‘first day’). Although exceptions exist, the first day of the bis sextum (February 24) was usually regarded as the intercalated or “bissextile” day since the third century. February 29 came to be regarded as the leap day when the Roman system of numbering days was replaced by sequential numbering in the late Middle Ages.
In the United Kingdom, a person born on February 29 legally attains the age of 18 on March 1 in the relevant year. In the European Union, February 29 officially became the leap day only in 2000.
In cases of New Zealand citizens, the NZ Parliament has decreed that if a date of birth was February 29, in non-leap years the legal birth date date shall be the preceding day, the 28th. This is affirmed in §2(2) of the Land Transport Act 1999.
In France, there is a humorous periodical called La Bougie du Sapeur (The Sapper’s Candle) published every February 29 since 1980. The name is a reference to the sapper Camember, a comic strip character born February 29, 1844 who was created by Georges Colomb in the 1890s.