Tuesday will see us experience what astrophysicists call a ‘leap second’, which occur occasionally to compensate for the slowing of the Earth’s rotation.
This year the extra second will be added at 00:59:60 on Wednesday, July 1 (BST) to allow the world’s clocks to catch up with the Earth to make sure they are as accurate as possible.
Leap seconds were first introduced in 1972 and have been used 25 times.
Rory McEvoy, Curator of Horology, Royal Observatory Greenwich, said: “The Earth’s speed of rotation has a tendency to slow – caused principally because of the relationship between Earth and the moon – but it can speed up. There is a possibility that a negative leap second could be added to UTC.”
The most recent was in 2012, when reports suggested it played havoc with the internet.
Websites including Reddit, Yelp, LinkedIn went down for a period of time.
There are fears the same could happen again, with financial institutions concerned about potential impact on stock markets are also wary of mishaps, particularly in Australia where the leap second will happen at 10am on July 1.
The potential problems mean there are vocal opponents of introducing the leap second, but scientists say it is essential for research purposes.
Members of the International Telecommunications Union, which sets the world’s clocks, will meet later this year to decide whether to scrap leap seconds completely.
Experts have suggested such a move means we could slip up to three minutes ahead of time by 2100, and about half an hour by 2700.
Who decided to use the leap second?
The International Earth Rotation and Reference Systems Service (IERS) based in France monitors the planet’s rotation and tweak time where necessary.
Dr Daniel Gambis, head of the IERS, announced in January that a “positive leap second” will be added to Coordinated Universal Time (UTC) on June 30, the international time standard which regulates clocks around the world.
In January, they sent out what may be one of the greatest bulletins ever, addressed to “authorities responsible for the measurement and distribution of time.”
UTC is based around atomic time, a method of measuring time based on the frequency of vibrations within an atom.
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