Coordinated Universal Time

After June 20, 2015, the last minute of this year will be of 61-seconds. Which means, this year we will have to wait one second more than usual to welcome the new year as timekeepers will add a “leap second” to the final minute of 2016.

The US Naval Observatory said in a statement that a ‘leap second” will be added on December 31, 2016 at 23 hours, 59 minutes and 59 seconds Coordinated Universal Time (UTC), which is calculated in Paris, France, at the International Bureau of Weights and Measures.

“This extra second, or leap second, makes it possible to align astronomical time, which is irregular and determined by Earth’s rotation, with UTC which is extremely stable and has been determined by atomic clocks since 1967,” the Paris Observatory said in a statement.

Conventionally, time is considered as based on the mean rotation of Earth, which was defined in this reference frame and the second is related to celestial bodies. However, for a precise reporting, atomic clocks are defined that offers much more precise ‘atomic’ timescale, which is independent of earth rotation.

The computations and measurements show that Earth runs slow at about 1.5 to 2 milliseconds per day as compared to atomic time. It further suggests that the difference between atomic time and Earth rotation time would be about one second after around 500 to 750 days.

The difference is calculated and observed by the International Earth Rotation and Reference Systems Service (IERS). The IERS is also responsible for synchronising time and monitors the difference in the two-time scales and calls for leap seconds to be inserted in or removed from UTC when necessary to keep them within 0.9 seconds of each other. The organisation was established in 1972 and since then it has 27 seconds in last 44 years. It is not much of a difference for normal people but it is huge in scietific terms where very precise measurements are required.

Delay of milliseconds can disrupt synchronisation of satellites moving them kilometers away from their actual path. Space agencies correct the time of satellites daily in order synchronise the time with Earth.

“The sequence of dates of the UTC second markers will be: 2016 December 31 23h 59m 59s, 2016 December 31 23h 59m 60s, 2017 January 1, 0h 0m 0s,” the IERS website states.

However, synchronising time can sometimes have adverse effects as it was seen back in 2012 when the addition of leap second crashed Mozilla, Reddit, Foursquare, Yelp, LinkedIn, and StumbleUpon. Also, people reported of several problems with programmes written in Java and Linux operating system.

Experts explain that such consequences are seen because of the addition of leap second is instantaneous and several computing systems use the Network Time Protocol, or NTP, to keep themselves in sync with the world’s atomic clocks. These protocols are not designed to deal with instant addition of an extra second which leads to crash.

To combat the problem, the tech giant Google has developed an algorithm called ‘leap smear’ which adds milliseconds on specific and predetermined time intervals just before the arrival of leap year. Thus, protocols are saved from such sporadic changes.

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