We have an extra day this year, because 2008 is a leap year, which means it has 366 days instead of the usual 365. In a typical year, the month of February has only 28 days. But in a leap year, a 29th day is added to February to make up for a technicality in the number of days in a year. Technically, a typical year lasts 365 days and six hours. Therefore, an extra day (called an intercalary, or leap day) is added every four years to a given year to account for the extra 24 hours that have accumulated. February is given the extra day, since it is the shortest month of the year.
The Romans were the first to come up with the concept of a leap year. Originally, their calendar years lasted 355 days, but they decided to add an extra 22 or 23-day month to them every two years to keep up with the seasons. They were inconsistent in this practice, however, and as a result, during Julius Caesar's life time, the seasons no longer occurred at the same times. To correct this, Caesar decided to eliminate the extra month and give various months one or two extra days instead, thus extending the calendar year to 365 days. He also wanted to add an extra day to the calendar every four years ---- following the 28th day of February. But after his death in 44 B.C., and until 8 A.D., the calendars were given an extra day every three years, not four. Yet again, the calendar wasn't in sync with the seasons.
Recognizing that Easter would eventually fall closer and closer to Christmas, Pope Gregory XIII reformed the calendar in 1582 so that a leap year would occur in any year that is divisible by four but not by 100, except when the year is divisible by 400. Thus, this year is a leap year, and 2012 and 2016 will be leap years also. By contrast, the years 1800 and 1900, century years, were not leap years because they are not evenly divisible by 400, and the years 2100, 2200 and 2300 won't be leap years either. The years 1600 and 2000 were leap years, however, and the years 2400 and 2800 will be also.
We still use the Gregorian calendar today. Our year of 365.2425 days is only off from our solar year by 0.00031, which will add up to a 24-hour error in 4,000 years. To correct this, it has been proposed that years evenly divisible by 400 shouldn't be leap years, but this rule has not been adopted.
If you were born on February 29, you may be used to celebrating your birthday a day early (on the 28th) or a day late (on March 1) during non-leap years. If so, your friends and family may call you a "leapling." Here are some notable "leaplings" who have made their mark on history:
Pope Paul III (born: 1468)
John Byrom --- English poet (born: 1692)
Ann Lee --- American founder of Shakers (born: 1736)
Gioacchino Rossini --- Italian composer (born: 1792)
John Philip Holland --- Irish inventor (born: 1840)
Frank Gavan Duffy --- Australian judge (born: 1852)
Herman Hollerith --- American statistician (born: 1860)
Morarji Desai --- Indian Prime Minister (born: 1896)
Jimmy Dorsey --- American bandleader (born: 1904)
Balthus --- French-Polish painter (born: 1908)
Dinah Shore --- American singer (born: 1916)
Arthur Franz --- American actor (born: 1920)
Al Rosen --- American baseball player (born: 1924)
Joss Ackland --- English actor (born: 1928)
Jaguar --- Brazilian cartoonist (born: 1932)
Jack Lousma --- American astronaut (born: 1936)
William H. Turner, Jr. --- American horse trainer (born: 1940)
Phyllis Frelich --- American actress (born: 1944)
Tim Powers --- American writer (born: 1952)
Jonathan Coleman --- Anglo-Australian entertainer (born: 1956)
Ian McKenzie Anderson --- British musician (born: 1960)
Lyndon Byers --- Canadian hockey player (born: 1964)
Chucky Brown --- American basketball player (born: 1968)
Antonio Sabato, Jr. --- Italian-born actor (born: 1972)
Ja Rule --- American rapper and actor (born: 1976)
Simon Gagne --- Canadian ice hockey player (born: 1980)
Darren Ambrose --- English football player (born: 1984)
Scott Golbourne --- English football player (born: 1988)
Sources: Imbornoni, Ann Marie. "Leap Year Explained." www.infoplease.com.
