I've often wondered why the 1800s are called the "19th century," the 1900s the "20th century" and so on. Why not call the it century they're presently in?

I've often wondered why the 1800s are called the "19th century," the 1900s the "20th century" and so on. Why not call the it century they're presently in?

— Marilyn H., Central Point

Sometimes our kids wonder what century we're living in, but we are in 2008, in fact, living in the eighth year of the 21st century.

In the Christian calendar, which all of the Western world follows, dates are recorded according to their relationship to Christ's birth. Whether you call it A.D. 2008 (A.D. is "Anno Domino,"** meaning "in the year of our Lord") or C.E. 2008 (common era) the year refers to how many years have passed since Christ's birth. **See March 29, 2008, Since You Asked for corrections to this column.

If you track the years back, you can see why the 1800s, for example, are called the 19th century. Think of the 1st century. It began with year 1, the year Christ is believed to have been born, and ended with the close of year 99**. Therefore, it was the 1st century but not the 100s (it might have been called the Zeroes). The 100s, or the 2nd century A.D., began with year 100 through the end of 199. The pattern has followed through time, giving the appearance of us being ahead of ourselves.

But then time has never been one of our strong points on planet Earth. Our atomic clocks are so perfect we have to grant them a leap second every couple years as the planet literally is slowing in its daily rotation by 1.4 milliseconds every day. And of course you know about our leap year calendar problem.

Send questions to "Since You Asked," Mail Tribune Newsroom, P.O. Box 1108, Medford, OR 97501; by fax to 541-776-4376; or by e-mail to youasked@mailtribune.com. We get so many questions we can't answer them all, but we'll try!