2016 will get an extra second to keep precision time devices precise

I'd wager that we are all familiar with the leap year, this is the year when February gets an extra day. Some will be familiar with a similar concept called the leap second and the last time a leap second was added to the clock as June 30, 2015. 2016 will get a leap second to keep precision clocks that precisely track time accurate. This leap second will come at the end of 2016.

The leap second is needed because time has to be kept accurate as the Earth's rotation slows. Scientists think that billions of years ago when the Earth first formed that it spun so fast a complete rotation took only six hours. We know today that a full rotation requires 24 hours. Highly precise endeavors require and extremely precise clock and having about 24 hours in the day doesn't cut it, these precise clocks need to be good down to the second.

This sort of clock is based on the vibration of the cesium atom and to account for that slowing an extra second has to be added occasionally. The International Earth Rotation and Reference System Service, the group responsible for synchronizing Earth time, says, "A positive leap second will be introduced at the end of December 2016. The sequence of dates of the UTC second markers will be: 2016 December 31, 23h 59m 59s, 2016 December 31, 23h 59m 60s, 2017 January 1, 0h 0m 0s."

Precision clocks in the US will add the extra second to the clock a bit before 7pm EST. Google plans to add its extra second to its official clocks in smaller increments over a 20 hour period. The US Naval Observatory will add the entire extra second at once to its master clock.