NASA says a range of factors can alter the speed of the planet’s rotation, from gravity wars between the Earth, moon and sun, to tides, earthquakes, and even El Nino.
So what will it look like on our clocks?
“The difference of 2 milliseconds – far less than the blink of an eye – hardly seems noticeable at first”. Energy transitions at the atomic level are used to mark the precise time.
The UTC (official name of GMT) was in fact devised to keep the atomic clocks and actual time in sync by allowing scientists to add an extra second at least once a decade.
Theoretically, the Earth makes one rotation in 86,000 seconds but in practice Earth rotates takes 0.002 seconds longer to make a full rotation.
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. Since then, 25 instances of the “leap second” have already taken place.
Today, at 8 p.m. ET, the leap second could have a big impact on the Internet, potentially shutting down websites for several hours.
Astronomers at the worldwide Earth Rotation and Reference Systems Service in Paris decided earlier this year on the extra tick of the clock – the 26 time that’s happened since the world started using atomic clocks, the Los Angeles Times reports.
So just before midnight Tuesday, an extra second will be tacked onto the day.
About 10 percent of large-scale computer networks will probably experience some glitches due to the leap second, Geoff Chester, public affairs officer for the United States Naval Observatory in Washington, told Bloomberg News. It could be that fewer leap seconds are needed because of earthquakes, volcanic eruptions or other geological events that cause the Earth to jiggle around on its axis. The next generation of atomic clocks – optical clocks – should achieve accuracies equivalent to losing or gaining no more than one second in the lifetime of the universe. To prevent this, some systems are switched off for one second; in the past, adding leap seconds had complicated things for computer systems.