IF YOU'RE the type of person for whom every second counts, you're in for a bonus at the end of the year.
Instead of the traditional countdown to the new year beginning "10, nine, eight . . .", you may wish to begin at "11 . . .", due to the addition of a "leap second" to clocks around the world.
The need for this arises every so often, explained Prof Luke Drury, senior professor of astrophysics at the Dublin Institute for Advanced Studies.
In effect it allows the Earth to catch up with itself, given the old girl is gradually slowing with age.
"The Earth doesn't spin at a completely uniform rate; it is gradually slowing down," said Prof Drury. This is mostly due to friction caused by the movement of the tides, but climate change is also having an effect.
Melt water from glaciers and ice caps gradually flows down towards the equator. The shift in mass is "like a spinning ballerina throwing out her arms", causing her speed to slow.
"You basically stop the clock to allow the Earth to turn just enough to catch up," he said.
Of course, such a small misalignment between time as dictated by clocks and time as dictated by the Earth's
orientation towards the sun only arises because we now use two measures of time - one based on the position of the Earth and a second independent measure based on atomic clocks.
An international agreement in 1970 established these two time scales, with the proviso that they can never fall out of alignment by more than a second.
The International Earth Rotation and Reference Systems Service keeps tabs on where Earth time is and periodically asks for a leap second to be added to keep Earth and atomic time within a second of one another.
This will be the 24th leap second added since 1972, with the previous one inserted on December 31st, 2005.
It is worth noting that a leap year, the practice every fourth year when our calendars include February 29th as an extra day, is not about time keeping.
It is about ensuring that our Gregorian calendar system stays in alignment with the celestial calendar.
Astronomers were unable to inform, however, about whether the women's prerogative of making marriage proposals in a leap year would also apply at the moment of a leap second.
Time will apparently stand still but only for a second, so it will have to be a very fast proposal indeed. Men, please take note.
