If leap seconds were not added, there would be a difference of up to three minutes by 2100 and a 30-minute difference by 2700. These seconds are added at intervals ranging from half a year to seven year periods.
For millennia, humans measured time based on astronomical events, such as the passage of the sun through the sky.
It is also possible for a second to be removed from the UTC (Universal Co-ordinated Time) timescale, although this has never happened.
So chances are you'll be shouting 'Happy new year!' and clinking glasses a second too early. Islamabad, Paris, Moscow, Tokyo, and most of the Eastern Hemisphere, on the other hand, will have one extra second in 2017.
VLBI measures the rotation of the Earth by observing the apparent positions of distant objects near the edge of the observable universe.
Ana Ivanovic retires from tennis at 29
There was speculation that she might even supplant Maria Sharapova as the most marketable player on the women's tour. Using her flat, powerful groundstrokes, she won her first WTA singles title in 2005 at just age 17.
"Leap seconds have to be inserted on average every 1-2 years during this century", Dr Kuhn says. This gradual slowing down of the Earth's rotation is caused by the moon's gravitational pull over the Earth.
No - the leap second shouldn't cause any issues. Google uses "leap smear", where it gradually adds milliseconds to its system clocks before the official arrival of the leap second, to avoid problems associated with the extended time.
"By adding a leap second, we're essentially stopping our atomic clocks to let the Earth catch up", explained USNO astronomer, Geoff Chester.
Geoff Chester of the US Naval Observatory, part of the IERS, said the leap second system was initiated in 1972, when the world's timekeepers chose to maintain two timescales, and explained why tides affect time. UTC defines what a second is, and it defines a grouping of seconds into minutes, hours, days, months, years, and so on. That means each second of the server clock will be calculated as, 1 sec = (1 sec + 13.9 µ secs).
So, I only say 2016 was a disgusting year because I think that every year is a terrible year, but this year was notable in that everyone else thought it was frightful, too.