‘Leap second’ syncronises Indian time with Earth’s spin on January 1,2017

The atomic clock was programmed to add an extra second to 2017 to compensate for a slowdown in the Earth’s rotation.
A ‘leap second’ was added to the Indian clock at 5:29.59 hours on January 1 to synchronise with the Earth’s rotational clock. 
  • As the atomic clock at the National Physical Laboratory (NPL) here struck 23:59:59 last night, it was programmed to add an extra second to 2017 to compensate for a slowdown in the Earth’s rotation.
  • Till now 27 leap seconds were added, Last leap second was added on December 31, 2016 at 23:59:60 (UTC). 
  • The difference between Coordinated Universal Time (UTC) and  International Atomic Time (TAI) increased from 36 seconds to 37 seconds.
Example: If Coordinated Universal Time is 12:00:00 then, International Atomic Time (TAI) is 12:00:37.

What is leap second?
leap second is a one-second adjustment that is occasionally applied to Coordinated Universal Time (UTC) in order to keep its time of day close to the mean solar time, or UT1.

Should we adjust our clocks to the Earth's slowing rotation, or should atomic clocks be solely responsible for measuring time?
The scientific community has so far failed to reach an agreement on this topic.
  • In 2003, a meeting named “ITU-R SRG 7A Colloquium on the UTC timescale” took place in Torino, Italy, where it was suggested that time be decoupled from the Earth’s rotation and leap seconds be abolished. No decision was reached.
  • In 2005, US scientists proposed to eliminate leap seconds and replace them with leap hours. The proposal was criticized for its lack of consistent public information and adequate justification.
  • In 2012, delegates of the World Radio communication Assembly in Geneva, Switzerland, decided once more to postpone the decision to abolish leap seconds and scheduled a new vote for 2015.
  • In 2015, the decision was again deferred to 2023.
Leap Seconds: Pros and Cons:
Arguments against leap seconds:
  • Leap seconds could cause disruptions where computers are tightly synchronized with UTC.
  • Leap seconds are a rare anomaly, which is a concern for safety-critical real-time systems (e.g. air-traffic control concepts entirely based on satellite navigation).
  • Astronomical time (UT1), which is defined by Earth's rotation, is not significant in most people’s daily lives.
In favor of leap seconds include:
  • There have been no credible reports about serious problems caused by leap seconds.
  • Some computerized systems that work with leap seconds are costly to modify (eg. antennas that track satellites).
  • Computer errors caused by leap seconds can be avoided simply by using International Atomic Time (TAI) instead of Universal Coordinated Time (UTC).
  • Desktop computers and network servers have no trouble coping with leap seconds.
  • Humankind has defined time by the Earth's rotation for over 5000 years – this tradition should not be given up because of unfounded worries of some air-traffic control engineers.