Enjoy the long weekend, if only for second

Fri Jun 29, 2012 7:22am EDT
 
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By Chris Wickham

LONDON (Reuters) - The world is about to get a well-earned long weekend but don't make big plans because it will only last an extra second.

A so-called 'leap second' will be added to the world's atomic clocks as they undergo a rare adjustment to keep them in step with the slowing rotation of the earth.

To achieve the adjustment, on Saturday night atomic clocks will read 23 hours, 59 minutes and 60 seconds before moving on to midnight Greenwich Mean Time.

Super-accurate atomic clocks are the ultimate reference point by which the world sets its wrist watches.

But their precise regularity - which is much more constant than the shifting movement of the earth around the sun that marks out our days and nights - brings problems of its own.

If no adjustments were made, the clocks would move further ahead and after many years the sun would set at midday. Leap seconds perform a similar function to the extra day in each leap year which keeps the calendar in sync with the seasons.

The grandly named International Earth Rotation and Reference Systems Service (IERS) based in Paris, is responsible for keeping track of the gap between atomic and planetary time and issuing international edicts on the addition of leap seconds.

"We want to have both times close together and it's not possible to adjust the earth's rotation," Daniel Gambis, head of the Earth Orientation Centre of the IERS, told Reuters.   Continued...