Not only is 2012 a leap year, but it will also include a “leap second“. On June 30, one second will be added to the clock, in much the same way that a day is added to the calendar for a leap year. Both events work on basically the same concept. The International Earth Rotation and Reference Systems Service, based in Paris has declared that the extra second will be added in order to maintain a balance between the atomic clock and Earth’s orbit. According to the IERS website and, the Earth’s rotation is actually longer than a day by a fraction of a second. The atomic clock, however, which measures time by vibrations in the element Cesium, does not have this margin of error. To compensate, the IERS adds a second every time that they can measure a difference between Earth’s clock and the atomic clock. The last leap second happened in December of 2008.

Obviously, since a second is such a small length of time, this change won’t require anyone to change their clocks, and most people will go their whole lives without noticing that leap seconds have even happened. In fact, it takes hundreds of years for the seconds to add up to a whole leap hour.

Leap seconds do cause their share of trouble, though, as the inconsistency can throw off sensitive technology like gps and air traffic control. Because of this, some people in these industries have advocated abolishing the leap second altogether.