Hong Kongers will have an extra second added to their holiday on July 1 in order to keep in line with the world’s official clocks.

The Hong Kong Observatory confirmed last month a leap second will be introduced between 7:59:59am and 8:00:00am on SAR Establishment Day  in order to keep in line with Coordinated Universal Time (UTC).

Hong Kongers will enjoy an extra second today as official timekeepers take into account the Earth’s slowing rate of rotation. Photo: Vicky Wong.

A leap second is a one second adjustment that is used every few years because the Earth’s rate of rotation is uneven and occasionally slows down. The reason for this slowdown has been attributed to natural events such as earthquakes.

The HKO says that all leap seconds have been positive since the first one took place in 1972. There have been 25 leap seconds so far.

According to the Wall Street Journal, it is difficult to gauge how computer systems around the world will react to having an extra second added to their day.

For instance in 2012 when the last leap second took place, a number of websites – including Amazon, Reddit, LinkedIn and Qantas – experienced technical glitches as a result.

In Hong Kong, the leap second will take place an hour and a half before trading on the Hong Kong Stock Market opens. Other markets such as Tokyo and Sydney would have already started trading at that point.

The HKO reminded those who worked in information technology, telecommunication, transport or finance industries to review whether or not their systems could handle leap seconds properly and to adjust where appropriate.


Vicky Wong

Vicky is a British-born Chinese journalist with three years of experience covering UK politics. She previously worked for PoliticsHome and has interned at Sky News and CNN International. She also co-produced and filmed a documentary about the Hong Kong protests for MSNBC, which won the grand student prize at the 2015 Human Rights Press Awards. She has a BA in Politics and International Relations from the University of Reading and moved to Hong Kong in 2014 to complete a journalism masters at the University of Hong Kong.