2016 was a bit longer as leap second added to synchronise time with Earth's rotational clock

Year 2016 was a second longer and we had to wait this bit to welcome the year 2017. But why? Well, because a leap second was added to the clocks across the world. In India, this leap second was added at  5:29.59 hours on December 31.

Now the question is why this extra second? Well, the leap second was added in order to synchronise with the rotational clock of the Earth.

When the atomic clock at the National Physical Laboratory (NPL) in New Delhi struck 23:59:59 on the night of December 31, 2016, it was programmed to add the leap second to 2017. It was done to compensate for a slowdown in the rotation of the Earth.

This barely had an impact of the daily life, however, in the fields of satellite navigation, astronomy and communication, it matters.

“The Earth and rotation around its own axis is not regular, as sometimes it speeds up and sometimes it slows down due to various factors, including earthquakes and moon’s gravitational forces. As a result, astronomical time (UT1) gradually falls out of sync with atomic time (UTC), and, as and when the difference between UTC and UT1 approaches 0.9 seconds, a leap second is added to UTC through atomic clocks worldwide,” D. K. Aswal, Director of NPL, said.

The NPL, one of the oldest laboratories in India, added the extra second to the Indian clock under the Council for Scientific and Industrial Research. The NPL has five atomic clocks and nearly 300 such pieces exist across the world.

Atomic clocks are so precise that the margin of error in its functioning is just of a second in 100 million years. 

“The leap second adjustment is not so relevant for normal everyday life. However, this shift is critical for applications requiring time accuracies in the nanosecond, which are critical in the fields of astronomy, satellite navigation, communication networks,” Mr. Aswal added.