The National Physical Laboratory (NPL) has revealed that it will be introducing the 26th leap second into UTC(NPL), the UK’s representation of the international time scale Coordinated Universal Time (UTC), immediately before midnight on 30 June 2015 i.e. tonight.
The introduction of an extra second follows the directive issued earlier this year by the International Earth Rotation and Reference Systems Service (IERS) based at the Paris Observatory. The extra second will help keep the international reference time based on atomic clocks in sync with solar time based on the Earth’s rotation.
The extra second will ensure that civil time doesn’t drift away from the time based on Earth’s rotation as if not corrected the drift would eventually result in clocks showing the middle of the day occurring at night.
Though such a situation won’t happen until hundreds of years, the difference will start becoming obvious over a period of few years.
Leap seconds were first introduced in 1972, but the international community has been split from day one regarding the need for leap seconds. NPL says that the UK Government believes that the consequences of breaking the link between civil time and the Earth’s rotation are not fully understood, and that the problems leap seconds currently cause can be dealt with by technical improvements.
The fate of the leap second is expected to be decided at the World Radiocommunication Conference in November 2015.
As the UK’s home of precise timing, NPL is developing ways to measure time ever more accurately and continuing to improve the performance of its atomic clocks. The next generation of atomic clocks – optical clocks – should achieve accuracies equivalent to losing or gaining no more than one second in the lifetime of the universe.