February 29, 2012--Leap Second

February 29th is my favorite quadannual day. Actually, it's the only day that comes around just once every four years.

Thus, technically, it is called an intercalary day [from Latin intercalārius , inter (“among”) + calō (“call out, proclaim”)] or bissextile day (also from the Latin, annus bissextilis, "leap year," literally, "the twice sixth-day").

It offers presidential candidates one more day to campaign since it always occurs during a presidential election year (not that we need more campaigning); stores have special Leap Day sales, following hard on the heals of Presidents Day; and, as time moves inexorably along, it slows down the aging process in that one's birthday during Leap Years includes one more day for denial.

Since for me, age has already done some of its inexorable thing, during much earlier Leap Days, when social life was very different than now, I looked forward to the tradition that on these days women were sanctioned to take the initiative in regard to dating and even making marriage proposals. As a shy and socially-inept adolescent and young adult I sat by the telephone on February 29ths from dawn to dusk. This waiting would suggest--quite accurately--that I usually had to hold on until the next Leap Year to revive feelings of potential attractiveness.

Inserting an extra day in the calendar every four years or so (more about the "or so" in a moment) is to compensate for the astronomic reality that earth's solar year is not 365 days but rather about 356 and a quarter days. But as with most things astronomical, things are not that simple.

For example, some exceptions to the Leap Year rule are required since the duration of a solar year is slightly less than 365.25 days. Years that are evenly divisible by 100 are not leap years, unless they are also evenly divisible by 400, in which case they are leap years. so 1600 and 2000 were leap years, but 1700, 1800 and 1900 were not. Similarly, 2100, 2200, 2300, 2500, 2600, 2700, 2900 and 3000 will not be leap years, but 2400 and 2800 will be.

Therefore, in a duration of two millennia, there will be 485 leap years. By this rule, the average number of days per year will be 365 + 1/4 − 1/100 + 1/400 = 365.2425, which is 365 days, 5 hours, 49 minutes, and 12 seconds.

Got it?

There's more, including a recent battle among scientists about one or-so second. As the New York Times reported, at a recent conference in Geneva, 700 delegates from 70 nations debated whether or not to abolish the leap second:

Unlike the better-known leap year, which adds a day to February in a familiar four-year cycle, the leap second is tacked on once every few years to synchronize atomic clocks--the world's scientific timekeepers--with Earth's rotational cycle, which, sadly, does not run quite like clockwork. The next one is scheduled for June 30. . . .

The United States is the primary proponent for doing away with the leap second, arguing that the sporadic adjustments, if botched or overlooked, could lead to major foul-ups if electronic systems that depend on the precise time--including computer and cellphone networks, air traffic control and financial trading markets--do not agree on the time.

Abolishing the leap second ''removes one potential source of catastrophic failure for the world's computer networks,'' said Geoff Chester, a spokesman for the United States Naval Observatory, the nation's primary timekeeper. ''That one second becomes a problem if you don't take it into account.''

While they battle it out, from habit, this Leap Day you'll find me wondering if the phone will ring and . . .