Leapin' lizards: It's Feb. 29 and the Net explains why

By Keith R. Darnay

This is a column 28 years in the making.

The last time I could have written a column about leap day on a Sunday leap day was Feb. 29, 1976. Disco was big, but the World Wide Web was not yet a gleam in the Internet's digital eye.

The next chance I'll get to write about leap day on a Sunday leap day will be 2032. Retro disco will be big and the World Wide Web as we know it probably will be as interesting as pet rocks, Barbie's breakup with Ken and Windows 3.1.

So I have to make the most of this rare occurrence today while I still have my hand on the pulse of the Net.

Or at least while I still have a pulse.

Feb. 29 is the extra day inserted into the calendar every four years to keep the calendar year in sync with the tropical year, or the time it takes the Earth to cycle through the four seasons during one orbit around the sun.

The calendar year has 365 days. Nice and neat. But it actually takes 365 days, 5 hours, 48 minutes and 46 seconds for the Earth to complete one orbit around the sun. Which means the calendar year is shorter than the tropical year. In four years, the discrepancy would amount to just under one full day (23 hours, 15 minutes, 4 seconds).

When the Julian calendar was introduced in 46 B.C., by Julius Caesar, astronomers were aware of the problem and inserted an extra day into the calendar every four years to make up the difference.

However, when averaged over time, this actually made the calendar year several minutes longer than the tropical year. This meant, according to the calendar, the astronomical beginning of each season would come earlier with each passing year.

By 1582, calendar spring was arriving almost two weeks early. Pope Gregory XIII introduced the Gregorian calendar, which deleted 10 days between Oct. 4 and Oct. 15, 1582, to bring the calendar back in line with the tropical year. Leap days were slightly modified to be added only in years divisible by 4 and only in century years divisible by 400. Thus, 2000 was a leap year, but 1900 and 2100 are not.

This means there are 97 leap days every 400 years under the Gregorian calendar instead of 100 leap days every 400 years under the Julian calendar.

Which means it will take 3,300 years for the Gregorian calendar, which we use today, to fall behind the tropical year by one day.

People are born every day and, obviously, some people will be born on leap day. It's estimated there are 200,000 people in the United States and 4 million people worldwide who have birthdays on Feb. 29.

What are the chances of being born on a leap day? About 1 in 500, according to the Infoplease almanac Web site (www.infoplease. com/spot/leapyear1.html).

Celebrities born on Feb. 29 include actor Dennis Farina, motivational speaker Anthony Robbins, serial killer Richard Ramierz, rapper Ja Rule and " American Idol" judge Randy Jackson.

If you want to learn more about leap day and the evolution of the calendar, these Web sites should keep you busy until the next leap year in 2008:

National Maritime Museum

www.nmm.ac.uk

Do a search on "leap year" to get great, authoritative information.

U.S. Naval Observatory

aa.usno.navy.mil/faq/docs/leap_years.html

A good explanation of leap year and calendars.

Why Leap Years?

www.timeanddate.com/date/leapyear.html

A succinct overview of it all.

LeapZine

www.leapzine.com

Home of the Honor Society of Leap Year Babies.

Leap Year Festival

www.leapyearcapital.com

Details on the festival and the host border town which bills itself as the "Leap Year Capital of the World."

When to Celebrate

www.straightdope.com/classics/a960209.html

A great article on when leap day babies should actually celebrate their birthdays and why, in general, your birthday anniversary isn't really the day on which you were born.

Born on This Day

www.born-on-this-day.com

Enter a date to see who else is born on that date.

(Keith Darnay is the webmaster and designer for bismarcktribune.com. His website is at www.darnay.com/iec.)