This year to be longer by one second

This year will be longer than usual -- by one second, the U.S. Institute of Standards and Technology said last Wednesday.
The earth is sufficiently out of sync that a leap second has been scheduled for 7 p.m. U.S. Eastern Standard Time on Dec. 31, said the institute.

A total of 24 leap seconds have been added since 1972, the last being in December 2005, because the earth is slowing and does not rotate exactly once every 24 hours, the Institute said.

The discrepancy went unnoticed until highly accurate atomic clocks were developed in the late 1960s. It was decided then, by international agreement, that operators of atomic clocks around the world would adjust the time of day by adding one second to the world's official time when needed.

http://www.spacedaily.com/reports/This_year_to_be_longer_by_one_second_999.html