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Arts / Entertainment

Crunching the numbers on Leap Year

February 27, 2012
by Savannah King

When people think of leap year, it may just be a reminder to wonder what it's for. But the conception of leap year turns out to have a rich history worthy of another look.

From Roman roots to modern-day controversies, leap years can have serious clout on our daily lives.

Taking the great leap
  • We follow the Gregorian calendar, which technically has only 365 days in a year. However, it actually takes the Earth 365.242199 days to orbit the sun.
  • Do the math: This means if we didn’t have leap years, we would lose 24 days worth of time over a span of 100 years. Our calendar would be totally messed up.
  • Julius Caesar was the first person to officially institute the leap year rule back in 45 B.C.
  • Each leap year, we also add a “leap second” on June 30. This serves to keep our atomic clocks perfectly aligned with the Earth’s rotation. If we didn’t have leap seconds, eventually – over thousands of years – time as we experience it would be totally out of sync with how Earth rotates.
  • Even though this leap second is critical, plenty of countries are pushing to abolish it because of backlash from some companies. The companies worry that every few years they have to stop all their systems and put everything on hold for exactly one second to accommodate this special unit of time, creating a logistical nightmare.     
  • A leap year actually has to adhere to special criteria to be considered a leap year: First, it has to be divisible by four. But if it’s also divisible by 100, it’s not a leap year. Unless it’s also divisible by 400 – because then it is a leap year. (That’ll warm up your calculator.)
  • In 2010, the Sony PlayStation Network was completely shut down when game consoles incorrectly identified that year as a leap year. Gamers could not use their consoles until the glitch was identified and corrected.
  • Anyone born on a leap day – this year, it’s Wednesday, Feb. 29 – is automatically invited to join the Honor Society of Leap Year Day Babies.
  • Back in the day, leap days were considered to be the one time it was okay for women to propose to men.
  • In Norway, the Henriksen family holds the world record for most leap-day births in one family, with all three children born on a leap day.

Remember the “Days of the Month” rhyme? The origins are obscure (and the rhyme varies), but it dates back to at least the 16th century:

Thirty days hath September,
April, June and November,
All the rest have 31,
Excepting February alone.
Which only has but 28 days clear
And 29 in each leap year

So, what if leap year hadn’t been invented? After about 700 years, we’d all be celebrating Christmas in the middle of summer!