KUALA LUMPUR: Today is an odd day. Literally. There will be 86,401 seconds today -- one more than every other day.
Horologists worldwide will stop the clock for one second today to compensate for the Earth's irregular velocity of rotation. This means the last minute of the day will last 61 seconds.
National Measurement Standards Laboratory senior principal metrologist Dr Mohd Nasir Zainal Abidin said the adjustment would be done in Malaysia, as in all time-keeping laboratories around the world.
"This is the 26th occasion since 1972 that a leap second adjustment had been made. The last was on Dec 31, 2008."
The national timekeeper said that for most people, a second may not matter, but from the standpoint of applications that require accuracy runnning into milliseconds, microseconds or nanoseconds, a one-second difference is "a lot of time".
"For industries such as communications, transportation, search and rescue, space exploration, banking transactions and navigation, every second matters," he said.
In the 1970s, the calculation of atomic time replaced the one based on the irregular rotation of the Earth.
Studies of the Earth's dynamics show that the velocity of the Earth's rotation is decreasing and, as a consequence, a rotational day is shorter than a day of 86,400 atomic seconds.
When atomic time was adopted, some communities of users, particularly those using celestial navigation, had requested that the time be synchronised with the rotation of the Earth.
"The Earth's rotation is monitored by the International Earth Rotation and Reference Systems Service and it announces the dates of application of any leap seconds required. It's usually timed for the end of June or December," said Nasir.