Earth takes just over 86,400 seconds for a complete revolution. But it wobbles on its axis and is affected by the gravitational pull of the Sun and Moon and the ocean tides, all of which brake the rotation by a tiny sliver of a second, AFP reported.
As a result, Earth gets out of step with International Atomic Time (TAI), which uses the pulsation of atoms to measure time to an accuracy of several billionths of a second.
This will be the 25th intervention to add a “leap second” to UTC.
“Today, time is constructed, defined and measured with atomic clocks that are infinitely more stable than astronomical time,” Noel Dimarcq, director of the SYRTE time-space reference system at the Paris Observatory told AFP.
“This allows us to ensure that everyone on Earth is on the exact same time.”
The extra second is added to UTC, also known as Zulu time, only ever at midnight, either on a December 31 or a June 30.
The leap second has long caused debate among member countries of the International Telecommunication Union (ITU), with some arguing for it to be abolished in favour of the exclusive use of atomic time.
Every time a second is added, the world’s computers need to be manually adjusted, a costly practice that also boosts the risk of error.
High-precision systems such as satellites and some data networks will have to factor in the leap second or risk provoking a calculation catastrophe.