Scientists at the Paris-based International Earth Rotation and Reference Systems Service (IERS) have added an extra second on December 31, to compensate for the slowing of the Earth's rotation.  

According to timekeepers, this means that the world’s clocks will go from 11:59:59 to 11:59:60 before turning to 00:00:00.

In astrophysics, this event is referred to as a leap second.  

Hassan Al Hariri, head of Dubai Astronomy Group, told Gulf News that the changes in time are made as a result of natural catastrophes, which end up slowing down the motion of Earth.

“For example, in 2004 there was the tsunami in Indonesia, and that natural disaster slowed down the earth’s rotation by 0.26 seconds in 2015. Also, large hurricanes can affect the momentum of the earth’s motion,” he said.   

“This concept is not new and from a lay person’s view, the extra second is equivalent to the click of a mouse. While it will have very minute effects, advanced computer systems will be taking that extra second into consideration,” said Al Hariri.  

As leap seconds can pose a threat to computer systems, the IERS – the group responsible for administering international time – typically give a six months’ notice about the time changes, and only places them at the end of December or June.   

However, according to the UK-based New Scientist journal, there have been calls to stop adding leap seconds and to let the earth’s rotation gradually diverge from the time.

“Instead of adding leap second every few years, we can make the modifications in the long run. So in every 100 years, an additional three minutes can be added. But this proposal is still under debate by the international community of scientists,” Al Hariri explained. 

source : gulfnews