Like a band of superheros keeping the world safe, the International timekeepers at the International Earth Rotation and Reference Systems Service (IERS) based in Paris will add a second, a ‘leap second’, to the clock on Saturday June 30 at midnight universal time. That’s 8 p.m. EDT Saturday. Universal time will read 11:59:59 followed by the unusual time of 11:59:60 before it strikes midnight.
Atomic clocks are the most accurate time keepers in the world, and the timepieces by which the world sets all other clocks. The rotation of the Earth is not quite as constant. It can change pace due to phenomenon such as global warming or changes in mass distribution caused by earthquakes. As a result, the time it takes the Earth to rotate on its axis and complete one full day is two milliseconds longer than it was 100 years ago, according to Geoff Chester, the spokesman at the U.S. Naval Observatory where the official U.S. atomic clocks are kept. Because of this difference, after many years the world’s atomic clocks would be ahead of planetary time, and the sun would set at noon.
To remedy this disparity, atomic clocks must be periodically synchronized, explained Daniel Gambis, head of IRES. “We want to have both times close together and it’s not possible to adjust the earth’s rotation,” he told Reuters. The system was first adopted in 1972 and this will be the 25th leap second. The last one was December 31, 2008 and the next one likely won’t be needed until 2015 or 2016. Much like the extra day in a leap year, which makes sure the calendar and the seasons are in line, the leap second matches human measurements with planetary time. In a hundred years or so, we may have to start adding 2 leap seconds a year.
The leap second is not without some controversy. Atomic clocks are used to set Coordinated Universal Time (UTC), and as such, are important to govern time standards for sattelite navigation, astronomy, banking computer networks, and international air traffic systems. Opponents would like a simpler less costly system with reduced room for error in making these manual changes. This past January, the International Telecommunications Union (ITU), the U.N. agency responsible for international communications standards called to abandon the leap second, but the group failed to reach consensus and will try again in 2015. A much broader discussion on the consequences of abandoning the leap second is needed, said Britain’s Royal Astronomical Society spokesman Robert Massey, as we would be decoupling measured time from the position of the sun.
If only cinderella had had an extra second at the stroke of midnight, before her coach turned into a pumpkin and her glass slipper disappeared. Here is your chance to use this additional time wisely.
Image credit: nist.gov