Forgot your password?
typodupeerror
Earth Science

Leap Second To Be Added Dec 31, 2008 255

Posted by timothy
from the pregnant-pause dept.
ammorris writes "Don't be the laughingstock of your friends when you shout 'Happy New Years' a second too early ... The International Earth Rotation and Reference Systems Service has announced that a leap second will be added on December 31, 2008 at 23h 59m 60s, meaning that this year will be exactly one second longer. The last leap second occurred Dec 31, 2005; they are added due to fluctuations in the rotational speed of the earth. You can read all about leap seconds on Wikipedia."
This discussion has been archived. No new comments can be posted.

Leap Second To Be Added Dec 31, 2008

Comments Filter:
  • Second! (Score:5, Funny)

    by tirerim (1108567) on Monday December 29, 2008 @04:00AM (#26255685)
    I tried to resist, but I still leapt at the chance...
    • 3 2 1 jokes in 3... 2... 1... 1...
  • by holophrastic (221104) on Monday December 29, 2008 @04:02AM (#26255689)

    Uhh, wouldn't it be nice if we were given a little bit more of a warning? Say, something like, oh a week?

    • Re: (Score:3, Informative)

      by Anonymous Coward
      Technically, the original announcement was in July. This is just a reminder.
    • by KiloByte (825081) on Monday December 29, 2008 @04:06AM (#26255701)

      The bulletin is dated 4 July 2008, it's just the Slashdot article that's late. Or even, just on time as a reminder.

    • by MichaelSmith (789609) on Monday December 29, 2008 @04:07AM (#26255713) Homepage Journal

      Uhh, wouldn't it be nice if we were given a little bit more of a warning? Say, something like, oh a week?

      You may laugh, but I work in Air Traffic Control. We rely on absolutely precise timing in a system distributed over 1000s of kilometres. Many components can be marked as non-functional by the system if they appear to have an incorrect clock.

      Every time we add a leap second we get issues raised. I have to say it is a real PITA.

      • by xous (1009057) on Monday December 29, 2008 @05:00AM (#26255905) Homepage
        Haven't they heard of NTP? http://en.wikipedia.org/wiki/Network_Time_Protocol [wikipedia.org]
      • Re: (Score:3, Insightful)

        by rew (6140)

        You mean that in a critical field-of-work a system that fails more often than "doesn't work on leap days" gets past the acceptance tests?

        I now understand where the pressure to remove leap seconds comes from. From the idiots that can't specify systems that handle them correctly.

      • by valen (2689) on Monday December 29, 2008 @05:42AM (#26256057) Homepage

        Yeah, we had problems in Google with these too; we have large networks of machines that used to use multiple different NTP servers (for resilience). Turns out not all NTP servers implemented leap seconds the same way, and many cluster based applications get upset when they aren't synchronized to within 100ms.

          Now, we run a dry-run of a fake leap-second with all software a few weeks before the leap-second failover. It's the only way to be 100% sure that applications changed since the last leap second won't have problems. Though, most unittest frameworks now have the ability to implement second skewing, since the suffering caused by the 2005 leap second.

          The main problem is that the POSIX description of how to do a leap second is retarded; you basically go from 00:00:00 to 00:00:59, some apps also get upset when they see the same time twice.

        John

        • Re: (Score:2, Funny)

          by Anonymous Coward

          (Score:5, leaks company procedures and shortcomings)

        • Turns out not all NTP servers implemented leap seconds the same way, and many cluster based applications get upset when they aren't synchronized to within 100ms.

          Given that most computers have utterly horrible tickers (irony: a $15 Timex watch keeps much better time than this $4,000 server), can you usually expect that much precision?

      • by Anonymous Coward

        Uhh, wouldn't it be nice if we were given a little bit more of a warning? Say, something like, oh a week?

        You may laugh, but I work in Air Traffic Control. We rely on absolutely precise timing in a system distributed over 1000s of kilometres. Many components can be marked as non-functional by the system if they appear to have an incorrect clock.

        Every time we add a leap second we get issues raised. I have to say it is a real PITA.

        What I find baffling is that architects/developers working in such a life-critical field managed to conceive application relying on days/minutes which are NOT fixed values. (a minute can have 59 or 61 seconds while a day can have 23 or 25 hours).

        That said, the clock of a Un*x system is usually calibrated in milliseconds since the epoch and this has absolutely zero, nada, zilch, nothing to do with leaps seconds. The fact that we decide that 31 dec 2008 with have a 61 seconds minute change *nothing* to the c

        • by Gnavpot (708731)

          the clock of a Un*x system is usually calibrated in milliseconds since the epoch and this has absolutely zero, nada, zilch, nothing to do with leaps seconds. The fact that we decide that 31 dec 2008 with have a 61 seconds minute change *nothing* to the correct calibration of the clock.

          Is that true?

          I know that this is how timezones, DST and leap years are handled, but are leap seconds handled like this too?

          In other words, if I ask a Un*x system about the number of seconds since epoch for 2008-12-31 23:59:5

        • I do like how people complain that they are trying to keep 'time' in keeping with actual observed sun/earth movements. If anyone is seriously using HH/mm/ss as an accurate system should move out of the pre-war era into the new fangled world of the microprocessor. I don't know about anyone else but I have in the past tried to do things with a computer and HHmmss and bugger me that was hard, then I used unix timestamps and lo life was easy (as long as someone has already done the module to convert timestamps
      • Why on earth would you use a calendar date in these systems, rather than a number of seconds from a fixed epoch date? Most computers store the time internally in such a format, as a time_t (which is either a large integer or a double, depending on the system), with the epoch date determined by the system designers. Converting between two such systems is just a matter of adding a fixed offset (the difference between the two epoch dates, in seconds). Converting to a calendar date is more complex, but the o
      • Re: (Score:3, Insightful)

        by HTH NE1 (675604)

        You may laugh, but I work in Air Traffic Control. We rely on absolutely precise timing in a system distributed over 1000s of kilometres. Many components can be marked as non-functional by the system if they appear to have an incorrect clock.

        Every time we add a leap second we get issues raised. I have to say it is a real PITA.

        Leap seconds were invented in 1972. You mean your systems didn't get leap second support addressed when you got your Y2K fixes?

    • by tyldis (712367)

      The summary gives the impression that they figured this out today. The announcement is just a reminder and a PR magnet.

      This has been known for quite some time and is significant for some industries (like my field of work; satellite telemetry).

    • Re: (Score:3, Funny)

      by darkpixel2k (623900)

      Uhh, wouldn't it be nice if we were given a little bit more of a warning? Say, something like, oh a week?

      Yeah! This totally f*cks my schedule. One second totally ruins New Years for me.

  • 2008?!! (Score:5, Funny)

    by gooman (709147) on Monday December 29, 2008 @04:05AM (#26255695) Journal

    Gah! I can't take another second of this!

  • by at10u8 (179705) on Monday December 29, 2008 @04:06AM (#26255697)
    Until 2007 legal time in the US was mean solar time, and that has no leaps, so this is the first leap second for the legal US time. Officially, of course, USNO and NIST were keeping UTC, but that didn't make it legal. The difference shows up in computer time scales [ucolick.org].
  • Longer, or shorter? (Score:4, Informative)

    by Smoke2Joints (915787) on Monday December 29, 2008 @04:21AM (#26255757) Homepage

    "Don't be the laughingstock of your friends when you shout 'Happy New Years' a second too early ... this year will be exactly one second longer."

    So... wouldnt we be shouting it one second later than everyone else?

    • by at10u8 (179705)
      If you're in London, where legal time is still mean solar time, then the legal new year happens in the middle of the UTC leap second.
    • Re: (Score:2, Funny)

      by johanatan (1159309)
      Maybe he's assuming that the general population would get this one right and we uninformed nerds would not? :-)
  • That's UTC (Score:5, Informative)

    by Bruce Perens (3872) * <bruce@perens.com> on Monday December 29, 2008 @04:34AM (#26255805) Homepage Journal
    Those of us in the U.S. will get to celebrate our extra second during a reasonable time of day, as it's in UTC. The local astronomy museum generally has a baloon drop at that time, so that the kids can feel they celebrated New Year's properly.
  • by Anonymous Coward

    If you messed up in 2008 you still have an extra second to make good.

    DON'T WASTE THIS GOLDEN OPPORTUNITY!

  • by Frosty Piss (770223) on Monday December 29, 2008 @04:37AM (#26255821)
    I work a graveyard shift. You can bet I'll bring this up to the boss. I don't work for free!
  • Wha ...? (Score:5, Funny)

    by resistant (221968) on Monday December 29, 2008 @04:48AM (#26255847) Homepage Journal

    Wait just a second, now! I ... oh.

  • Damn Bush (Score:5, Funny)

    by Anonymous Coward on Monday December 29, 2008 @04:54AM (#26255871)

    Bush will do anything to remain president just a little longer.

  • by unassimilatible (225662) on Monday December 29, 2008 @04:54AM (#26255873) Journal
    I will be able to give my GF an extra round of pleasure, with time to spare.

    OK, just kidding - I am a /.'er and obviously don't have a GF. But if I did, I am confident in my abilities that I could, in fact, perform my duties in the allotted one second.
  • by Opportunist (166417) on Monday December 29, 2008 @04:55AM (#26255877)

    What timezone will it be added to at midnight?

    Yes, I know, it is not nitpicking because it's nontrivial for certain high precision science projects... even though I couldn't think of one right now, but it's gonna be quite important for someone.

    But just to add a joke: Effin' great, as if daylight saving didn't put enough stress on the mechanics of my clocks!

    • by n3tcat (664243)
      The only timezone that matters. GMT.
  • The International Earth Rotation and Reference Systems Service has announced that a leap second will be added on December 31, 2008 [CC] at 23h 59m 60s

    My understanding is that the last 60 seconds of the year will be 1/60th of a second longer. Or will my GPS actually read "23h 59m 59s" twice?

    • Re:Added When (Score:5, Informative)

      by Detritus (11846) on Monday December 29, 2008 @06:07AM (#26256127) Homepage

      The length of the second doesn't change. An extra second is added. I work with precision timing systems where this is an issue.

      The sequence is:

      23:59:59 UTC
      23:59:60 UTC
      00:00:00 UTC
      00:00:01 UTC

      That means that the valid range for seconds is 0..60 and it is possible to have 61 seconds in a minute. You need to know this if you are using a programming language with range checks.

      GPS uses its own time scale that isn't affected by leap seconds.

      • maybe we should use stardates? they just sound so cool

        *read in a Picard voice*
        stardate 48182.647... captains log supplemental... #1 is humping my leg... off boy off! ... this Data guy is really freaking me out lately ...

      • by Gnavpot (708731)

        GPS uses its own time scale that isn't affected by leap seconds.

        I don't doubt that it does that internally, but GPS receivers usually put a timestamp on the position. How is this timestamp affected?

        Will a GPS receiver continue to convert the internal time to UTC following an outdated algorithm which is hardcoded into the receiver, or is the conversion algorithm part of the data received from the satellites?

        In other words: Can we trust the time from a GPS receiver, or will two receivers show a difference o

        • by imadork (226897)
          The time scale GPS uses is basically the UTC timescale that was in effect when the GPS system went first live (1980?). This is the time that GPS broadcasts, forever and ever.
          Along with that time, there is a broadcast of the current offset between GPS time and the current UTC time. This offset goes up by 1 on every leap second since the GPS system first went live.
          So as long as the receiver is getting all the GPS broadcasts, it will always know what the correct UTC time is.
      • That means that the valid range for seconds is 0..60 and it is possible to have 61 seconds in a minute. You need to know this if you are using a programming language with range checks.

        Oh, shit.

        Well, at least I'll know what I'll be doing on my first day of work next year.

  • by extagboy (60672) on Monday December 29, 2008 @05:13AM (#26255955) Homepage

    Or, is that only in the vista ultimate edition?

  • Nah (Score:2, Funny)

    by Tablizer (95088)

    No big d.......eal.
       

  • Second?

  • Fluctuations? (Score:3, Interesting)

    by Woek (161635) on Monday December 29, 2008 @05:53AM (#26256087)
    I'm sorry? Fluctuations in the rotation of the earth? You mean the earth is accelerating and breaking? It has nothing to do with the fact that a rotation around the sun is not exactly 365.25 rotations around our own axis? hmm...
    • Re:Fluctuations? (Score:5, Informative)

      by Nick Barnes (11927) on Monday December 29, 2008 @06:12AM (#26256151)

      I'm sorry? Fluctuations in the rotation of the earth? You mean the earth is accelerating and breaking?

      Yes, that's exactly what we mean (well, "braking" rather than "breaking"). The earth does not have a constant angular velocity. To conserve angular momentum, as the mass distribution of the earth changes (e.g. due to glacial rebound), the spinning of the earth speeds up and slows down. It also slows down a little due to tidal braking. So a "day", as measured by the rotation of the earth relative to the fixed stars, is not exactly 86400 seconds. It's generally a little more, around 86400.001 seconds at present, and it varies from day to day and from year to year. Now that civil time (UTC) is kept with atomic clocks, this is a genuine problem. Leap seconds are introduced to keep UTC close to UT1 (astronomical time).

      It has nothing to do with the fact that a rotation around the sun is not exactly 365.25 rotations around our own axis? hmm...

      That's right. Leap seconds have nothing whatsoever to do with that. They don't affect the calendar. That's what leap days are for. Leap days keep the calendar in sync with the seasons (by setting the average calendar year length to 365.2425 days, very close to the vernal equinox year which is currently 365.242374 days).

      • Re:Fluctuations? (Score:5, Informative)

        by bitrex (859228) on Monday December 29, 2008 @07:39AM (#26256497)
        The redistribution of mass after the 2004 Indian Ocean undersea earthquake was enough to measurably affect the rate of the Earth's rotation; the Three Gorges Dam project will also have a minute effect due to the concentration of water in the reservoir that's formed.
        • by Gnavpot (708731)

          the Three Gorges Dam project will also have a minute effect due to the concentration of water in the reservoir that's formed.

          Pun intended?

      • by at10u8 (179705)
        Leap seconds do affect the calendar, but only if you expect that calendar to be good for more that 10000 years. Designing any human system to be good for more than 1000 years is somewhat of a conceit. Then again, designing a human system to fail in less than 1000 years might be given a different sort of apellation. This sort of choice is what the timekeepers of the world are trying to make as the ITU-R debates abandoning leap seconds.
    • The leap-second is caused by the rotation around the sun not being exactly 365.25 days.

      However, the rotation around the Earths axis isn't all that smooth. It indeed accelerates and breakes due to tidal movements, atmosferic influences and interference with the Earths polar wobble.

      The day-to-day difference can be as high as a few seconds, but averages taken over a long(ish) period are very stable. It has to be, conservation of momentum-wise.
    • Re: (Score:2, Informative)

      by Anonymous Coward

      It has nothing to do with the fact that a rotation around the sun is not exactly 365.25 rotations around our own axis?

      No, it does not. Leap days are about keeping the calendar in sync with the seasons. Leap seconds are about keeping the clock in sync with the rotation of the earth. These are two different components of motion, and they are handled with different measures.

    • by Deadstick (535032)
      It has nothing to do with the fact that a rotation around the sun is not exactly 365.25 rotations around our own axis?

      If it were, there would be 364.25 solar days in a year.

      rj

    • Astronomers have been measuring subtle changes in Length-of-Day for decades. Its the advent of atomic clocks that has made this very precise. Length-of-Day responds to changes in mass distribution in the earth - like the spinning ice-skater who extends or contracts arms to change spin rate. Generally the main cause are ocean currents and seasonal weather patterns. In turn, these may be affected by small changes in solar output. Very large earthquakes like Indonesia 2004 will lift or drop enough rock to aff
      • by Deadstick (535032)

        There's also a theorized seasonal component caused by sap rising and leaves growing in trees in alternate hemispheres, but that's pretty well down in the noise.

        rj

  • by Terje Mathisen (128806) on Monday December 29, 2008 @06:19AM (#26256193)

    The UTC second 60 gets added at midnight only at those locations where UTC == local time, i.e. places like England.

    For us in the rest of Europe, the leap second will be added an hour after local midnight, i.e. at 01:00:60 CET.

    Terje

  • Leisure-suit up! This is going to be legend... wait for it...

  • ....the faster time flies by...

    But damn'it... ya all don't have to help it.

  • To be subtle, they added the leap second to the one time in the entire year when everyone (at least in that time zone) is watching the clock and counting along with it.

  • by cei (107343)

    Damn. I've been following the International Earth Rotation and Reference Systems Service (IERS) emails for years and this one managed to slip into my spam filter. Thanks slashdot! for making sure I didn't miss it this year!!!

    (A great bonding moment with my father was counting along to 61 with the atomic clock signal on the short wave while sitting by the sundial at the local science museum...)

  • Leap leap... (Score:5, Informative)

    by dna_(c)(tm)(r) (618003) on Monday December 29, 2008 @12:05PM (#26258443)

    ...meaning that this year will be exactly one second longer...

    No it isn't. It's a 86401 seconds longer. Than last year. Or 86400 longer than the previous leap-second-year 2005. Oh, yeah, it's exactly 1 second longer than 2004 and 1996.

    I confess enjoying myself as a time nazi. Should not forget to count february 29th...

    • Re:Leap leap... (Score:5, Informative)

      by HTH NE1 (675604) on Monday December 29, 2008 @02:01PM (#26259715)

      I'd mod you up if I could. Instead, I'll add these bits of trivia:

      The last time we had a leap second and a leap year was in 1992. The last time we had it on December 31 was 1976.

      The only time we had two leap seconds (June 30 23:59:60 and December 31 23:59:60) was on leap year 1972, the first year leap seconds were applied, and making 1972 the longest year.

  • The stock market will lose 20% of its value and the government will give an extra bagillion dollars in bailout money.

    Let's be done with '08 already - let's add that extra second to a good year

    /sarcasm

Put no trust in cryptic comments.

Working...