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When does a minute last 61 seconds?

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On this coming Sunday June 30, intrepid horologists from around the world will daringly attempt to hold back the relentless onslaught of time. Well, to be fair it won't actually be that difficult. July 1st is scheduled to start an entire second later than it should, a feat of temporal distortion that will be accomplished by making the final minute of the month last 61 seconds.

And should you feel put out by this, you can take it up with the Earth and its wobbly spin.

2012 features a leap second — that ever so important added slice of time that compensates for inconsistencies in the Earth's rotation. It takes our planet just over 86,400 seconds to make its 360-degree rotation. But because the Earth is affected by the gravitational pull of the Sun and Moon, along with the rolling of the tides, our planet's rotation is slightly slowed down.


These rotational mis-steps cause the Earth to get out of synch with International Atomic Time (IAT), which uses the pulsation of atoms to measure time to an accuracy of several billionths of a second. In order to resynchronize solar time with IAT time, the Coordinated Universal Time (UTC) is adjusted every few years to give us the odd 86,401 second day.

Now, while this might seem like much ado about nothing, a recent article by Laurent Banguet in Cosmos Magazine noted that it's not without controversy:

The leap second has long caused debate among member countries of the International Telecommunication Union (ITU), with some arguing for it to be abolished in favour of the exclusive use of atomic time.

Every time a second is added, the world's computers need to be manually adjusted, a costly practice that also boosts the risk of error.

High-precision systems such as satellites and some data networks will have to factor in the leap second or risk provoking a calculation catastrophe.


It's for this reason, notes Banguet, that rocket launches are never scheduled for leap-second dates.

This will be the 25th intervention, with the last three leap seconds happening in 2008, 2005, and 1998. Back in 1972, the year they started the practice, they had to add an excruciating two seconds to the clock.


So, what are you going to do with that extra second on June 30?

Image via D. French.