'Leap Second' Added To Official Time Overnight

The last minute of Tuesday had 61 seconds in it as a "leap second" was added to the official time set by atomic clocks.

While 23:59:59 usually becomes 00:00:00, the leap second meant that the time became 23:59:60.

Leap seconds are used in the same way as leap years - keeping the clock in sync with the Earth and its seasons.

Changes to the 400 atomic clocks maintained at laboratories around the world are agreed by the UN's International Telecommunication Union.

The last time the extra second was added, in 2012, sites such as Reddit, Foursquare, Gawker and LinkedIn crashed.

This time around, many companies said they had planned for the disruption.

Google (Xetra: A0B7FY - news) , for example, added on fractions of a second to its systems throughout the day. The technique is called a "leap smear".

Stock exchanges in Japan, Australia and South Korea used a similar technique, Bloomberg reported.

But New York avoided the problem altogether by closing the stock markets early.

Computers and software cannot be programmed with leap seconds in advance, as they are typically only announced a month before they come into effect.

Because of the problems caused by adding the seconds, the process will be reconsidered at the World Radiocommunication Conference in Geneva in November.

Peter Whibberley, senior research scientist at Britain's National Physical Laboratory said: "There are consequences of tinkering with time. Because leap seconds are only introduced sporadically it is difficult to implement them in computers and mistakes can cause systems to fail temporarily.

"However, we have always taken the Earth's rotation as the ultimate reference for timekeeping, and astronomers and navigators still make use of it.

"We shouldn't break the link without carefully weighing the consequences."