"Dream, Dream, Dream! Conduct these dreams into thoughts, and then transform them into action."
- Dr. A. P. J. Abdul Kalam
30 Dec 2016
This year will last a second longer as a "leap second" will be added to the world's clocks on New Year's Eve by the timekeepers. The extra second will be inserted at the US Naval Observatory's Master Clock Facility in Washington, DC at 23 hours, 59 minutes and 59 seconds Coordinated Universal Time (UTC) which corresponds to 5:29:59 am Indian Standard Time on January 1.
Usually a day has 86,400 seconds. December 31, 2016, however will have 86,401. The extra second which will be added at the end of this year will account for the inconsistencies between super accurate human atomic time keeping and earth’s natural if less inconsistent rotation speed. While atomic clocks define a second very rigidly and precisely, seconds based on earth’s rotation are slightly off and variable due to tidal friction as the moon’s gravity tugs on the earth’s oceans. As a result keeping the two time keeping systems within 0.9 seconds of each other requires an extra second now and again to keep them fully in sync.
After the insertion of the leap second in December, the cumulative difference between UTC and TAI will be 37 seconds. Confusion sometimes arises over the misconception that the occasional insertion of leap seconds every few years indicates that the Earth should stop rotating within a few millennia. This is because some mistake leap seconds to be a measure of the rate at which the Earth is slowing. The one-second increments are, however, indications of the accumulated difference in time between the two systems. 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.
Measurements show that the Earth, on average, runs slow compared to atomic time, at about 1.5 to 2 milliseconds per day . It was observed that after roughly 500 to 750 days, the difference between Earth rotation time and atomic time would be about one second. Instead of allowing this to happen a leap second is inserted to bring the two time-scales closer together.