Ooh, a government conspiracy that involves some of my colleagues.
The time of the winter solstice on 12/21/2012 has been changed from 11:11 to 11:12. Something sinister is obviously afoot.
Given that the Naval Observatory is probably the most precise observatory in the world I find this highly unusual. A minutes change is huge! What’s going on here?
Best guess? It’s a precision issue. The time is specified to the minute, which means you have to decide to round or not. If the calculated time was 11:11:29 and changed to 11:11:30 — a mere second longer — in a recalculation (which might happen depending on, say, how many leap seconds had been added since you did the previous calculation, or other factors), you would display it as 11:12.
Adding leap seconds would move the wall clock time to be smaller, not bigger.
Note, however, that the USNO may simply have recalculated using the new paradigm instead of the old one. As of 2003-01-01 the IAU resolutions specified the use of a new conventional system which, at that time, had no equinoxes or solstices because it had no self-consistent concept of ecliptic, therefore no expressions for calculating their times. It was not until the General Assembly in 2006-08 that the IAU passed a resolution indicating how the eclliptic shall be defined, and the papers detailing the expressions for that were not published until 2007. So in that sense the years 2003 through 2006 had no equinoxes or solstices.
You’re right, but the scenario I was thinking of was this: we were adding leap seconds every year in the late 90’s. If we anticipated adding them at a similar rate in the predictions at that time, we would be off because we had a long stretch this past decade where we didn’t add any.