If you live in the UK (or anywhere else in the same time zone for that matter) then the traditional New Year’s countdown won’t cut it this year.
Timelords have decided that 2016 is one of those years where we need to add on an extra second (a leap second) in order to keep the clocks right.
So when the clocks hit 23.59.59 on New Year’s Eve in the UK, they will then move to 23.59.60 before moving on to 00.00.00 on January 1, 2017.
The change will happen all over the world at exactly the same time, so, for example, on the east coast of the USA it will happen at 18.59.59 and at 15.59.59 for those on the other side of the US.
The reason we need leap seconds is because of the speed of the Earth’s rotation.
We learned at school that it takes exactly 24 hours for the Earth to complete one full rotation, but that is not strictly true.
There are 86,400 seconds in 24 hours and the actual time it takes for the Earth to complete a full rotation is 86,400.002 seconds.
For the most part this does not really make a huge amount of difference. Nobody sets their watches to that level of accuracy or would complain if a colleague turned up 0.002 seconds late for a meeting.
Peter Whibberley, a senior research scientist at the UK’s National Physical Laboratory in Teddington, told Sky News: “Leap seconds are needed to prevent civil time drifting away from Earth time.
“Although the drift is small – taking around 1,000 years to accumulate a one-hour time difference – if not corrected it would eventually result in clocks showing midday before sunrise.”
The International Earth Rotation and Reference Systems Service in Paris decides when leap seconds are needed, and this is the 27th time a leap second has been introduced since 1972.
Leap seconds are usually introduced in the final minute of June or December, but they can also be implemented in March or September.