Will Ockenden reported this story on Tuesday, January 6, 2015 08:21:01

ASHLEY HALL: If you're the type of person that treasures every second of life, you can rejoice. You've just been granted an extra one in 2015.



The Paris Observatory in France says it's again time to correct the world's clocks.



The leap second will be added on the 30th of June this year.



The extra second is added every now again because the rotation of the globe is slightly out of sync with the highly accurate atomic clocks.



It may only be a single second, but last time one was added in 2012, many web servers crashed because of problems with computer operating systems.



Will Ockenden has been speaking to Nick Stamatakos the chief of Earth Orientation Parameters at the US Naval Observatory, which is responsible for managing the America's atomic clocks.



NICK STAMATAKOS: There will be leap second added to UTC time, at the end of the day on June 30th, 2015.



WILL OCKENDEN: So a whole extra second on June 30th, this year. So instead of 60 seconds in a minute, there's 61?



NICK STAMATAKOS: Yeah, or for that day there will be 864001 seconds instead of 86400 seconds, so the length of the day that you and I and everybody in the Earth knows will have an extra second.



WILL OCKENDEN: Why do they need to do this? I think the last one was in 2012, so I guess it's three years since this has had to happen, why now?



NICK STAMATAKOS: Well the real simple explanation is the Earth is slowing down a little bit. The atomic clocks keep very accurate time, the Earth relative to the atomic clocks, the measurements are telling us 'Oh the Earth's slowing down'. So they add an extra second to something they call UTC, which is Universal Time, in order to make sure that the rate of UTC is the same as atomic time.



WILL OCKENDEN: So our atomic clocks are a lot more accurate than the rotation of the Earth?



NICK STAMATAKOS: Oh, God yes. Oh, God yes - yeah.



WILL OCKENDEN: Why has there been in recent years a reluctance I suppose to add leap seconds, because if you look back in the history of when leap seconds were added in the 70s when it was all created, there was almost one every year.



Then throughout the 80s there was one every couple, but then throughout the 90s and the 2000s it really stopped adding seconds until… so why was it so I guess fashionable back then and we've seen less seconds added now?



NICK STAMATAKOS: It's just the physics of things. The Earth isn't as slow as it was in the 70s. Relatively to the 1970s, it sped up a little bit. It's still slower than atomic time, it's still marching along- the Earth rotates at a rate that's slower than atomic clocks were set to but the Earth's actually sped up just a little bit from the 1970s.



WILL OCKENDEN: So people in the 1970s who thought it did drag on were actually accurate?



NICK STAMATAKOS: Ah, yeah that they're… right.



ASHLEY HALL: Nick Stamatakos from the United States Naval Observatory, speaking to Will Ockenden.