This is the Guardian. One second. It might seem insignificant, but one humble little second going awry can interfere

with the stock market, GPS or even the power grid.

Which is why government representatives

from around the world recently came together in Paris to get rid of the leap second.

It's a second we add to our clocks when they get out of time with the Earth's rotation,

which apparently happens quite often and it can cause real trouble.

So from 2035 we're scrapping the leap second and letting our

times drift. But what on earth are these different times?

And will it matter if they get out of sink?

From the Guardian, I'm Madeline Finley and this is Science Weekly. J.T Janssen, you are the chief scientist at the National Physics Laboratory NPL.

And the reason that we're talking to you is because there are these two times and we've decided to get rid of the second that kind of brings them both together and the two times are astronomical time and coordinated universal time. What are these two different methods of

telling time? How do they both work? That's a really good question. If I ask

somebody what is a day, they'll probably, well a day is 24 hours, 60 minutes in an hour and 60 seconds in a minute.

So a day lasts about 86,000 seconds and every day is exactly the same. But there's also another definition of a day

when the Earth spins around its axis, that's what we call an astronomical day. And those two are not the same. Over time the earth has been

slowing down a little bit due to the fact that the earth is not a solid

object it's got a liquid core and there are oceans and continents

which are moving and that means that an astronomical day is actually becoming slightly longer and that's where the leap seconds come in.

If you want to keep the Earth rotation exactly the same as the atomic time,

you have to occasionally add a second and since the atomic time was introduced in the 1960s there have been

about 37 seconds added to keep earth's rotation in sync.

So I'd never really imagined the earth like this, I guess this marble filled with water that's changing its rotation and as you said most of us go by

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