This New Year’s countdown will be one second longer as the National Physical Laboratory — the UK’s national measurement institute and the birthplace of atomic time — introduces the 27th leap second into UTC. The additional second will keep the timescale based on atomic clocks in sync with time based on the Earth’s rotation.
The next leap second will be inserted on December 31, 2016. This will be the 27th leap second added since their adoption in 1972. Image credit: National Physical Laboratory.
The International Earth Rotation and Reference Systems Service, based at the Paris Observatory, measures the Earth’s rotation and announces when a leap second is needed roughly six months in advance. They typically occur every two or three years.
A leap second is usually inserted in the last minute of either December or June, immediately prior to midnight, although the last minute of March or September may also be used. All leap seconds so far have been positive, resulting in the final minute of the UTC day having 61 seconds.
Since their introduction in 1972, 26 leap seconds have been added to UTC.
This will be the 27th leap second added. The last leap second was inserted on June 30, 2015.
Whilst leap seconds are needed to keep atomic time in sync with astronomical time, they can cause problems if not properly implemented.
“Atomic clocks are more than a million times better at keeping time than the rotation of the Earth, which fluctuates unpredictably,” explained Peter Whibberley, senior research scientist in the Time and Frequency group at the National Physical Laboratory (NPL).
“Leap seconds are needed to prevent civil time drifting away from Earth time. Although the drift is small — taking around a thousand years to accumulate a 1-hour difference — if not corrected it would eventually result in clocks showing midday before sunrise.”
“Because leap seconds are only introduced sporadically, they have to be manually programmed into computers and getting them wrong can cause loss of synchronization in communication networks, financial systems and many other applications which rely on precise timing,” said Dr. Leon Lobo, strategic business development manager for NPL Time®.
Based in Teddington, Middlesex, NPL is a world-leading center of excellence in developing and applying the most accurate standards, science and technology available.
Established in 1900, NPL has been home to a number of world-leading figures from science and engineering, including Alan Turing, recognized as the father of modern computing; Robert Watson-Watt, the inventor of radar; Donald Davies, who developed packet-switching, the basis of modern computer communications, and Louis Essen who developed the world’s first working atomic clock.
NPL continues this great tradition and is currently home to one of the world’s most accurate clocks (NPL CsF2), which is accurate to one second in 158 million years; and is leading thinking in areas such as graphene and carbon metrology.
“The most accurate atomic clocks still occupy entire labs,” NPL researchers explained.
“By making accurate atomic clocks portable, we could unlock the benefits of precise timing for countless applications.”
“In the near future, we could use miniature atomic clocks to send unhackable communications, improve deep space navigation, and eventually integrate them into smartphones, increasing data transfer rates in communications networks.”
