If you live in the Western Hemisphere (Londoners, New Yorkers, you know who you are), you'll have to wait an extra second before going in for that NYE kiss. In order to follow IST, the clocks need to be adjusted after the insertion of "Leap Second". And although the second before midnight Universal Co-ordinated Time technically corresponds to 3:59:59 p.m.
Counting down to 2017 will take longer than usual this New Year's Eve as clock experts compensate for a slowdown in the Earth's rotation.
How often is a leap second?
A leap second, applied to Coordinated Universal Time (UTC) adjusts the time to match the mean solar time, which is based on the position of the sun in the sky. The extra second helps account for inconsistencies between the Earth's natural rotation speed and the ridiculously accurate atomic clocks that timekeepers use. With the one scheduled for today, the UTC and the TAI will only differ cumulatively by 37 seconds.
Why do we have leap seconds?
This can also be called as like the mismatch in the clock and earth rotation time. The Earth is not as accurate as the cesium atom, and actually slows by approximately two milliseconds per day. Seconds have never been taken away, only added. The decision as to when to add a leap second is determined by the IERS, for which the USNO serves as the Rapid Service/Prediction Center.
Time is being calculated since a very long time. Therefore 2016 needs to be adjusted to match the Earth's rotation movement. UTC consists of a time scale that combines the output of more than 300 highly precise Atomic clocks worldwide, including the one at CSIR-NPL. On the other hand, opponents think the leap-second system is "hopelessly muddled and not fit for objective in our fast-paced, networked world".
When was the last leap second added?
"Last time, we did this on June 30, 2015".
When was the first leap second added? Civil time must be adjusted so that the world's atomic clocks do not vary from the Earth's rotational time by more than 0.9 seconds, according to the observatory. Earth's rotation is slightly getting slower which affects the global time.
Since 1972, 26 leap seconds have been added to our clocks. The organisation was established in 1972 and since then it has determined 10 seconds of the delay.