It happened.

A weird convergence of clock and calendar the likes of which won't happen till next century.

We're talking about 12:12:12 on 12-12-12.

For the second time today, it happened - and the planet's still here, and the country still hasn't gone over a fiscal cliff.

OK, not exactly a big event.

Except for those who booked wedding chapels for the hour and date in Vegas and other cities.

But this milestone does mark the end of a period with frequent numerologically curious date patterns.

When the calendar turns 2013, no longer can the year match the month, at least until the first New Year's of 2101. (Technically, that begins the new century because there was no year zero.)

Oh, there will still be quadruples every 11 years (2-2-22 is next), and yearly doubles (1-3-13), but they lack the proper symmetry factor.

Yes, Pi Day happens every 3-14, but the extra cool ones, where the year comes into play, will quickly come and go. There are just 3-14-15 - matching the mathematical constant's first five digits - and 3-14-16, which is closer to its actual value of 3.14159 etc.

A yearly series of countdowns by ones ended with 12-11-10, and palindrome fans, who had their heyday from 11-1-11 to 11-22-11 last November, will have to settle for the strained likes of 3-1-13 or 02-11-20 until next century.

Ascending strings have only two years left - 11-12-13 and 12-13-14 - until 1-2-34. And after next year, you'll have to wait until 1:02 3-4-56 to again include hours and minutes.

Patterns can always be found, of course. It'll just be tougher in years that exceed the number of months.

Counting by odds or evens, for example, suggest the likes of 5:07:09 on 11-13-15.

It's a Friday the 13th, by the way.

Contact staff writer Peter Mucha at 215-854-4342 or pmucha@phillynews.com.