…the addition of a leap second…


This year’s leap second—the 26th to be added to UTC since 1972—exists because time was traditionally based on a full rotation of the Earth and was related to heavenly bodies, which defined the length of the day.

This rotational time, called UT1, divides the day into 86,400 seconds.

But the atomic era demanded more exact timekeeping, and the world began doing business by UTC in 1972.

The two time scales, though, aren’t quite in sync, because Earth spins a bit slower each year due to tides and internal processes that create a gap between the two scales.

The International Earth Rotation and Reference Systems Service monitors this difference and periodically inserts a leap second to keep the two in tandem.

The difference between atomic and rotational time is tiny—only an hour or so every thousand years.

But the leap second causes a host of timekeeping issues, because no clock can accommodate an extra second.

It probably seems a little trivial to bother about seconds and put so much effort into correcting the slight anomaly, but…

“for the stock exchange, one second is important. For an airport, one second is important. For global navigation satellite systems, the difference of a second is unacceptable.”

Navigation systems work by measuring the time it takes a signal to travel between a known satellite location and a receiver. Such systems require extreme precision on the level of nanoseconds, or billionths of a second.

Information from National Geographic.

16 Comments CherryPie on Jun 30th 2012

16 Responses to “Time For…”

  1. Andrew says:

    “because Earth spins a bit slower each year”

    Seems to be spinning faster and faster to me. When I was young a day lasted for ages. Now it’s almost over as soon as I’ve got up and got my head into gear. But maybe it’s just that my head is working slower and slower each year. Those fancy clocks you show are very nice.

    • CherryPie says:

      This year for me seems to be spinning faster than ever. I am told as the years go by this is inevitable…

      But I am also told that time is not linear and the speeding up of time is not inevitable and that time is an illusion…

      The Mayan Calendar tells me that the world is going to end in December and that is why time seems I little confusing right now…

      I don’t believe the world is going to end but time does seem to be speeding up and getting the better of me…

  2. jamsodonnell says:

    I know how you both feel… but as Ford Prefect would say “Time is an illusion lunchtime doubly so!”

  3. Claude says:

    Ô temps! suspend ton vol, et vous, heures propices, suspendez votre cours…
    O time! suspend your flight, and you, happy hours, suspend your race…
    (Le Lac: Lamartine – 1820)

    Time did not listen to Lamartine, and has paid no attention to me.
    Actually, the more I complained, the faster it went.

    Great photos, Cherie.

  4. james higham says:

    Just adore those clocks!

  5. Bernard says:

    I never give seconds, a ’second thought’. You see -

    We are but minuets – little things -
    Each one furnished with sixty wings,
    With which we fly on our unseen track,
    And not a minuet ever comes back.

    We are but minuets – each one bears
    All it’s burdens of joys and cares;
    Then calmly bear minuets filled with pain -
    The worst of minuets cannot remain.

    We are but minuets when we bring
    Dewdrops from the pleasure spring
    So taste their sweetness while yet we stay -
    A minuet and we vanish away.

    We are but minuets – use us well,
    For our use you must one day tell;
    Who uses minuets has hours to use,
    Who loses minuets, years must lose.

    Bernard :)

  6. CrashRyan says:

    very cool clocks!

  7. Astrid says:

    ‘Time’ is a strange thing. Clocks fascinate me. I love the way some clocks are made. The one you show, is a wonderful piece of art. I love the little statues around the clocks.
    The skeleton is often seen in relation to ‘time’. I wished I had more time to ’study’ the subject.
    I am scrolling through your blog. Wonderful pictures again. I know I am more like a weekly visitor. But your blog is a wonderful place to visit and enjoy. Thank you.

    • CherryPie says:

      Time is strange, sometimes it goes by quickly and other times at a snails pace. You would love this clock, you can go up inside the tower and see some of the revolving figures from the back of the clock.

      Thanks Astrid I am glad you enjoy your visits here. I am a bit slow to comment on everyone these days too…

  8. Ha… Guess one has to live up to 1,000 years old to tell the one hour difference. ;)
    I miss Prague! :)
    It’s one of my favourite cities in Europe.
    Have you been to Budapest, C?
    There are lots of art nouveau buildings in Budapest too. :)

    • CherryPie says:

      I think if I lived that long I might be a wise old sage but I would probably be a bit bored…

      I love Prague, the lady behind reception at the hotel said that because I loved Prague so much I must visit Budapest the following year because I would love it too. She also said I must go back and tell her what I thought of the place. I still haven’t been ;-)