Dec. 31, 2009 at 4:30 PM ET
I'll be taking Friday off for the turnover to a new decade, the 2010s. And yes, it is a new decade.
The way I see it, the decade-counting scheme is different from the sometimes-confusing convention for centuries and millennia: If you're talking about the third millennium or the 21st century, you start with 2001. That's because the ordinal numbers "third" and "21st" are used in the context of a counting system that started with the year 1, not the year zero. But if you're talking about a decade, you're talking about time frames like the 1960s or the 1990s - time frames that began in years ending with zero (1960 or 1990, respectively).
Thus, the decade of the 2000s (or the "Aughts," or the "Noughties," or the "double-oh decade") began on Jan. 1, 2000, in the final year of the 20th century. That's the decade which is ending today. The 2010s begin on Friday, Jan. 1, 2010, and that's the extra day I'm taking off.
To tide you through the long weekend, here are some Web links to decadal discussions:
Check out The Volokh Conspiracy for further discussion on the decade-counting question. And while you're surfing around the Web this holiday weekend, give a look to my newly published book, "The Case for Pluto." You can also find out what I'm up to via my Twitter account (http://twitter.com/b0yle) or my Facebook page.