Tonight's 'Leap Second' Is Hot Tocking Point

This weary/manic/glorious/tragic/bizarre year will last one second longer than you think. As 2008 circles the drain, here comes the pithy news item about the "leap second." It's exactly what it sounds like. Tonight, timekeepers will slide an extra second into the world's clock. Tick tock tick tock TICK TOCK.

It will happen here, in Washington, a stroke before 7 p.m. The clock on the front lawn of the Naval Observatory will linger at 18:59:59 for two seconds instead of one. Then it will proceed, as if nothing happened, to 19:00:00.

Most computer clocks and cellphones will take note of this. You will not.

Perhaps you should. This minor quirk might soon vanish in a tussle of global proportions. The Brits want to keep the leap second. The United States and the world's other major powers want to dispose of it, thereby erasing the risk it poses to global telecommunications and navigation.

But if we get rid of the leap second, we effectively cut our ties to the sun.

"It would be a really bold cultural step to cut that link of maybe 5,000 years of history of measuring time," Royal Observatory timekeeping curator David Rooney says from London, where tonight, in the dying moments of 2008, BBC Radio will add a seventh pip (tone) to its traditional six-second countdown to the next hour, and where pennies will be removed from Big Ben's pendulum to slow it slightly in the final hour before midnight Greenwich Mean Time.

Tick tock tick tock TICK TOCK.

The leap second is a relic from the 1970s. Physicists whipped up this artificial hiccup to keep atomic clocks, which are reliably steady, aligned with the rotation of the Earth, which is slowing at a rate of two-thousandths of a second per day. So every now and then (1998, 2005, today) we allow the planet to catch up so that the sun remains highest at noon instead of, say, 11:59 a.m.

A leap second is kind of like a leap year, in that both are attempts at dicing cosmic progression into whole numbers: years made of days and days made of seconds. An extra day is notable. An extra second is nothing. Right?

It's one-86,400th of a day.

It's several billionths of a 75-year lifetime.

It's a blink.