New Year’s Eve. The night when everyone squeezes their post-Christmas selves into something sparkly to drink too much and pretend they know the words to ‘Auld Lang Syne’. You might panic that you’ve missed midnight or get carried away when some joker starts a hoax countdown, but once it’s nearly midnight, you know the drill.

This year, though, the New Year’s Eve countdown is going to be a little different, because 2017’s grand entry will be delayed by one second.

A ‘leap second’ has been officially added to compensate for a slowdown in the Earth’s rotation. The extra second will occur as clocks strike midnight, after 23:59:59, making the countdown longer than usual.

The change is required because standard time lags behind atomic clocks, which provide a stable universal time. ‘Leap seconds are needed to prevent civil time drifting away from Earth time. Although the drift is small – taking around 1,000 years to accumulate a one-hour difference – if not corrected it would eventually result in clocks showing midday before sunrise,’ explains senior research scientist Peter Whibberley from the National Physical Laboratory in London.

So, remember, that’s ten, nine, eight, seven, six, five, four, three, two, one… pause… Happy New Year!