Everyone knows that the month of February has only 28 days, right? Well, not in a leap year!

Every fourth year an extra day is added to the end of the month, creating a special day known as leap day, or February 29.

The leap day was created by Roman Emperor Julius Caesar in 46 B.C. Astronomers had calculated the time it takes for
the Earth to circle the sun, known as a solar year. The number they came up with was 365 days, plus about 6 hours. This
extra bit of time would add up to approximately 24 hours, or one day, after four years.

Caesar's solution was to add an extra day at the end of February every fourth year. This change would keep the solar year
in time with the Roman calendar year. Later, scholars figured out that the extra amount of time was actually slightly less
than six hours, and in A.D. 1582, the Catholic Church altered the rule for calculating when a leap day would be added.


The new rule said that a leap day would be added every four years except in century years (years ending with two zeros)—
unless that year could be evenly divided by 400.

Take the year 1900: It is a century year and is not evenly divisible by 400, so 1900 was not a leap year. However, the year
2000 is evenly divisible by 400, so it was a leap year.

What does all that math mean? By adding leap days, it is possible to make sure holidays happen around the same date
and during the same season each year.

Raenell Dawn, co-founder of the Honor Society for Leap Year Day Babies, likes to explain it this way: "You know when
you're on a swing and you're swinging next to your friend, and you're not swinging in time—you're swinging opposite? And
then you're getting closer to swinging in time with each other, and then, all of a sudden, you're swinging right in time with
each other! That's the way the calendar was before [leap] days made [the calendar year] swing together [with the solar
year]."

Sometimes it can be hard if you're born on a leap day. Dawn remembers being told by other kids, "You can't play with us—
you're only two." Of course, she might have been two in leap years, but was really closer to eight in regular years!

During non-leap years, most "leapers," as people born on February 29 are known, celebrate their birthday either on
February 28 or March 1. But when a real leap-day birthday occurs, many decide it's really time to party!

John Strohsacker went to school with two other kids who, like him, were born on February 29. He remembers his mother
throwing big birthday parties for him and the two other leapers every time leap day rolled around. The whole class would
be invited to attend.

"She took something that normally kids would probably tease you about, and she turned it around. You have this big party
every four years, and so other kids are actually jealous—they wish they were born on leap day!" Strohsacker said.

And Dawn also is quick to point out the advantages of being a leaper. "People have always said we're young at heart, that
we're all big kids."

Sounds like being a leaper can be something to jump about!

Related Links
Honor Society of Leap Year Day Babies/LEAPzine
John Strohsacker's Leap Day Site

   
© 2002 National Geographic Society. All rights reserved.