If you're used to counting down the New Year from 10, 9, 8, etc. this year you're going to have to make sure you go from 11! Yes, a "leap second" is going to be added to the atomic clock between 2008 and 2009 in order to stay in step with the Earth's irregular, gradually slowing rotation. (Atomic clocks have an inaccuracy of less than one second in 200 million years.)

It's the 24th time this has happened since the practice was started in 1972, but only the first time in three years. The IERRSS (International Earth Rotation and Reference Systems Service) will mark the extra second at the stroke of midnight on Wednesday in Greenwich, England, the home of Coordinated Universal Time.

Why do we need to do this, you ask? Apparently gravity (as well as some man-made factors like global warming), causes irregular axis rotation, which means the planet lags behind the atomic clock on average two milliseconds per day. At the moment, we're behind roughly 6/10ths of a second. So the extra second will put us about 4/10ths of a second ahead in '09.

All this is to say that you now have a perfectly legitimate excuse when you show up half a second late at your first meeting in "˜09.

"Erg! Blasted leap second! I totally forgot. It won't happen again, promise."

If you own an atomic clock, on December 31st, at 7 p.m. ET, you'll notice that the minute beginning at 6:59 p.m. will contain 61 seconds. In some versions of the clock, the number 59 will flash twice. If you want to watch it on your computer, check out this site at the same time just indicated.