Slashdot Mirror

← Back to Stories (view on slashdot.org)

Leap Second To Be Added Dec 31, 2008

Posted by timothy on 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."

41 of 255 comments (clear)

  1. Second! by tirerim · · Score: 5, Funny

    I tried to resist, but I still leapt at the chance...

    1. Re:Second! by Anonymous Coward · · Score: 4, Insightful

      It's like raising a puppy. The worst punishment possible is to pay no attention.

      The Internet is full of idiots/trolls/criminals/mentally ill. Banning is not a solution. After banning they just start to hide and use a proxy.

      Ignoring is the best way.

  2. Gee, thanks for the notice by holophrastic · · Score: 3, Funny

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

    1. Re:Gee, thanks for the notice by Anonymous Coward · · Score: 3, Informative

      Technically, the original announcement was in July. This is just a reminder.

    2. Re:Gee, thanks for the notice by KiloByte · · Score: 4, Informative

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

      --
      The creatures outside looked from Alt-Right to Antifa; but already it was impossible to say which was which.
    3. Re:Gee, thanks for the notice by MichaelSmith · · Score: 5, Interesting

      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.

      --
      http://michaelsmith.id.au
    4. Re:Gee, thanks for the notice by fastest+fascist · · Score: 5, Insightful

      No-one ever R's the FA, so the date on the bulletin is completely irrelevant. If it's not in a slashdot summary, we don't know about it.

    5. Re:Gee, thanks for the notice by xous · · Score: 5, Informative

      Haven't they heard of NTP? http://en.wikipedia.org/wiki/Network_Time_Protocol

    6. Re:Gee, thanks for the notice by MichaelSmith · · Score: 5, Informative

      Yes, but we are talking about interfaces between a lot of different networks, each of which have their own GPS based time reference. An NTP daemon in each network talks to the GPS device, but there is no way to be sure that all the daemons will slew the time at the same rate.

      --
      http://michaelsmith.id.au
    7. Re:Gee, thanks for the notice by valen · · Score: 5, Interesting

      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

    8. Re:Gee, thanks for the notice by Anonymous Coward · · Score: 5, Interesting

      Some people mistakenly think NTP is a silver bullet for handling timing issues.

      NTP is great for keeping consistent time *over time*. It is horrible for handling stuff like a leap second, it simply takes too long.

      Some systems use GPS, some use IRIG-B and some use NTP. Some handle leap seconds and some don't.

      If you work with telemetry, like I do, you need time to be 100% correct all the time or else the data is worthless. This leap second is actually causing NASa and other space agencies to not do satellite supports close to midnight on new-years eve UTC.

    9. Re:Gee, thanks for the notice by xous · · Score: 3, Informative

      Then switch to a stable time scale: http://en.wikipedia.org/wiki/International_Atomic_Time

    10. Re:Gee, thanks for the notice by Detritus · · Score: 4, Interesting

      NTP isn't good enough for many systems. Where I work, millisecond level accuracy and resolution is the bare minimum. Some applications require microsecond level accuracy and resolution. That's why we have dedicated timing systems and timing distribution systems. NTP is used on systems, like general purpose PCs, that don't have a requirement for accurate time.

      --
      Mea navis aericumbens anguillis abundat
    11. Re:Gee, thanks for the notice by Lumpy · · Score: 4, Funny

      know about what?

      I dont even read the Summary, so what the heck are we even talking about?

      --
      Do not look at laser with remaining good eye.
    12. Re:Gee, thanks for the notice by teridon · · Score: 4, Informative

      "Slew the time"? What system does that? According to the following page, the NTP server announces the leap second in advanced, and "well-behaved" kernels count the extra second like they are supposed to; i.e. there is no slewing:
      http://www.cis.udel.edu/~mills/leap.html

      --
      I hold it, that a little rebellion, now and then, is a good thing. -- Thomas Jefferson
    13. Re:Gee, thanks for the notice by nabsltd · · Score: 4, Informative

      The NTP daemon is normally used to interface with GPS clocks and to distribute time around a LAN. It never allows time to just jump. It always slews the clock.

      This, of course, is wrong.

      First, by default it steps the time on startup, with a default limit of 1000 seconds offset, but you can disable this limit.

      Second, after startup, by default it slews the time unless the offset is greater than 128ms, in which case it steps the time. The 128ms value is configurable via the "tinker" command, but it is not recommended that it be changed.

  3. 2008?!! by gooman · · Score: 5, Funny

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

    --
    "Kittens give Morbo gas!"
    1. Re:2008?!! by aaron+alderman · · Score: 4, Funny

      Sounds like a Bush plan to keep him in the Whitehouse as long as possible. Damn Republicans messing with our science.

  4. legally speaking, it's the first leap for the US by at10u8 · · Score: 5, Informative

    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.

  5. Longer, or shorter? by Smoke2Joints · · Score: 4, Informative

    "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?

  6. Re:legally speaking, it's the first leap for the U by ta+bu+shi+da+yu · · Score: 5, Informative

    Yes, yes, that's Nix vs Hedden and it was ruling by the U.S. Supreme Court in 1893. The court ruled that in the common parlance of the time a tomato was seen to be a vegetable and not a "fruit of the vine", working from the assumption that most people at it for a main course instead of a dessert. I think that if you were going to pick up on the ridiculous nature of the case you'd focus on the reason behind the court case — that taxes needed to be paid on imported vegetables and yet not on imported fruit.

    --
    XML is like violence. If it doesn't solve the problem, use more.
  7. That's UTC by Bruce+Perens · · Score: 5, Informative

    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.

    --
    Bruce Perens.
  8. I'll have to mention this to HR... by Frosty+Piss · · Score: 5, Funny

    I work a graveyard shift. You can bet I'll bring this up to the boss. I don't work for free!

    --
    If you want news from today, you have to come back tomorrow.
    1. Re:I'll have to mention this to HR... by sleeponthemic · · Score: 5, Funny

      No... you work for braaaiiinnnss

      --
      I record my sleeptalking
  9. Wha ...? by resistant · · Score: 5, Funny

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

    --
    A truly excellent pizza parlor is a delight unto the heavens. Treasure the sauce and the toppings!
  10. Damn Bush by Anonymous Coward · · Score: 5, Funny

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

  11. Excellent news for my sex life by unassimilatible · · Score: 4, Funny

    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.

    --
    Slashdot "libertarians": Small government for me, big government for those I disagree with. -1, I disagree with you
    1. Re:Excellent news for my sex life by Tablizer · · Score: 5, Funny

      I will be able to give my GF an extra round of pleasure, with time to spare.

      You'll have to hope for a leap-inch or two before that happens
                     

      --
      Table-ized A.I.
  12. Will windows automatically adjust my clock for me? by extagboy · · Score: 3, Funny

    Or, is that only in the vista ultimate edition?

  13. Re:how will my computer know by TCM · · Score: 3, Interesting

    I don't suppose this leap second has been encoded into timezone information like daylight saving time has been.

    So I would just run ntpd and expect the clock to step 1 second.

    At second thought, I would expect ntpd to gradually slew system time since 1s is too small an offset to step the clock at once. Maybe it would be better to stop ntpd and restart it with -g or even delete its drift file since this second is not an error of the system clock but artificially introduced? Anyone know?

    --
    Of course it runs NetBSD. BTC: 1NT7QvbetmANwaMzhpVL6
  14. Fluctuations? by Woek · · Score: 3, Interesting

    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...

    1. Re:Fluctuations? by Nick+Barnes · · Score: 5, Informative

      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).

    2. Re:Fluctuations? by bitrex · · Score: 4, Informative

      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.

    3. Re:Fluctuations? by Nick+Barnes · · Score: 3, Informative

      There is a drift, and there are fluctuations.

      Regarding the drift: The day length is getting gradually longer by about 1.7 milliseconds every century (+2.3ms due to tidal braking, -0.6ms due to glacial rebound). In about 1820 the day was 86400 seconds; now it is longer than that. In a thousand years, the day will be about 86400.017 seconds, and we will need a leap second every couple of months.

      [Note: I am simplifying a little here for the sake of clarity by ignoring the difference between a solar day and the stellar and sidereal days, which are about 4 minutes shorter].

      Regarding the fluctuations: There are fluctuations of the earth's angular velocity on many timescales. It fluctuates with weather, with the seasons, and with major events on the surface (e.g. a dam creating a new reservoir) and in the earth's crust (e.g. an earthquake or major volcanic eruption) and deeper interior (e.g. we don't really know). All these events are minor rearrangements of the mass of the earth, which change its moment of inertia. Conservation of angular momentum dictates that the angular velocity must change, and it does. Of course the earth isn't a rigid body and that complicates all this. Learn about Geodesy if you want to know more.

      In the 1990s the day length was approximately 86400.003 seconds, so we needed a leap second every year. For poorly-understood reasons (possibly some sort of deep mantle activity), the earth's rotation speeded up around the year 2000, and for a while the day length was about 86400.0004 seconds. Now it is slower again, about 86400.001 seconds. These changes all come under the "fluctuations" heading.

      There is an organisation called the IERS - International Earth Rotation and reference Systems Service - which collects measurements of all this stuff to very high accuracy and produces all sorts of reports, bulletins, data sets, etc etc.

  15. Re:Added When by Detritus · · Score: 4, Informative

    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.

    --
    Mea navis aericumbens anguillis abundat
  16. Leap second at UTC, not Local midnight! by Terje+Mathisen · · Score: 5, Informative

    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

    --
    "almost all programming can be viewed as an exercise in caching"
    1. Re:Leap second at UTC, not Local midnight! by sidyan · · Score: 4, Informative

      00:59:60 CET, you mean.

      And there are other timezones besides Greenwich Mean Time and Central European Time in Europe too: Eastern European Time, Moscou Time and even a smattering of Samara Time and Yekaterinburg Time.

  17. why rely on hh/mm/ss instead of millis elapsed... by Anonymous Coward · · Score: 3, Insightful

    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 correct calibration of the clock.

    How distributed systems across the globe came to rely on hh/mm/ss speaks, well, a lot about the plain dumbness of many people.

    But do they really? I pity the poor sick, under-brained people who designed those GPS if they're really that deeply flawed.

  18. Leap leap... by dna_(c)(tm)(r) · · Score: 4, Informative

    ...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...

    1. Re:Leap leap... by HTH+NE1 · · Score: 4, Informative

      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.

      --
      Oh, say does that Star-Spangled Banner entwine / The myrtle of Venus with Bacchus's vine?
  19. 3... 2... 1... by dorianh49 · · Score: 3, Funny

    3 2 1 jokes in 3... 2... 1... 1...

    --
    Gravity is a contributing factor in nearly 73 percent of all accidents involving falling objects. -Dave Barry