Leap Day Countdown

Leap Day is February 29, the bonus calendar day added roughly every four years to keep our clocks in step with Earth's journey around the Sun — a once-in-1,461-days occasion celebrated with quirky traditions, leapling birthdays and the sense of getting an extra day for free.

History

Leap Day exists because Earth does not orbit the Sun in a tidy number of days: a full trip takes about 365.2422 days. In 45 BC Julius Caesar, advised by the Alexandrian astronomer Sosigenes, introduced the Julian calendar, which added one extra day every four years to absorb the leftover quarter-day. The Romans did not count a 'February 29' as we do — they doubled February 24 instead, calling it 'bis sextus dies', the twice-sixth day before the Kalends of March, which is why leap years are still formally known as bissextile years. The Julian fix was slightly too generous, running about eleven minutes long each year, and by the sixteenth century the calendar had drifted roughly ten days out of line with the seasons. In 1582 Pope Gregory XIII's reform refined the rule: century years are leap years only if divisible by 400. That is why 2000 was a leap year but 1900 was not and 2100 will not be — a small correction that keeps the Gregorian calendar accurate to about one day in 3,300 years. Around the astronomy grew a playful folk culture. An Irish legend tells of Saint Brigid persuading Saint Patrick to let women propose marriage on the day, a custom that flourished on cheeky Victorian and Edwardian postcards and survives in Ireland and Britain as 'Bachelor's Day'. In 1928 bartender Harry Craddock of London's Savoy Hotel invented the Leap Day cocktail, and since 1988 the twin border towns of Anthony, Texas and Anthony, New Mexico have styled themselves the 'Leap Year Capital of the World', throwing a multi-day birthday festival for 'leaplings' — the estimated five million people worldwide born on February 29.

Meaning

Leap Day is a lighthearted reminder that our calendar is a human invention doing its best to keep pace with the heavens. The extra day is, quite literally, borrowed time — the accumulated quarter-days of four ordinary years returned to us all at once — and many people treat it that way, using February 29 to attempt something they would never do on an ordinary date. For leaplings, it is the rare year when their true birthday actually appears on the calendar, often marked with milestone-sized parties. For everyone else it is a small celebration of astronomy, timekeeping and the pleasure of a genuine rarity: a whole day that only exists once every four years.