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Leap Second At The End of 2005

Posted by CmdrTaco on from the correct-your-watches-immediately dept.

Ruff_ilb writes "Because of the discrepency between an ephemeris second (the fraction 1/31,556,925.9747 of the tropical year for 1900 January 0 at 12 hours ephemeris time) and the second of atomic time (the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium 133 atom), we're left with more than leap years. In order to ensure that the the atomic time and civil stay coordinated, "Civil time is occasionally adjusted by one second increments to ensure that the difference between a uniform time scale defined by atomic clocks does not differ from the Earth's rotational time by more than 0.9 seconds."" And Happy New Years everyone ;)

9 of 269 comments (clear)

  1. A cool thing to do by rolypolyman · · Score: 5, Funny

    If you watch carefully for that leap second, you can do a freeze-frame flying kick like in The Matrix.

  2. Re:How did you use yours? by Extrudedaluminiu · · Score: 5, Interesting

    Do any NTP servers keep track of these seconds?

    --
    -vs, me@acm.jhu.edu
  3. The hard way by Anonymous Coward · · Score: 5, Funny

    Adjusting the clock is of course the easy way to solve the mismatch between our ideal time and earth's rotation.

    Real engineering solution would involve changing earth's rotation speed to match the clock. Any takers?

    1. Re:The hard way by MyLongNickName · · Score: 5, Funny

      Adjusting the clock is of course the easy way to solve the mismatch between our ideal time and earth's rotation

      Oh yeah? It took me about ten minutes to adjust all the clocks in my house due to the damn leap second. Multiply this by the 100 million households in the nation, and we have a very serious issue here.

      I demand that George Bush pull us out of whatever God forsaken U.N. treaty that got us into this mess.

      --
      See my journal for slashdot ID's by year. Mine created in 2005. http://slashdot.org/journal/289875/slashdot-ids-by-year
  4. time.gov by srblackbird · · Score: 5, Informative

    I watched the time at Time.gov: 23:59:56 (UTC) =>23:59:57=>23:59:58=>23:59:59=>23:59:60!=>00:00:0 0
    It was Amazing! This was the first time for me... *remebers where I was at that moment

    --
    "The test of the morality of a society is what it does for it's children." -Dietrich Bonhoeffer
  5. old news by Viriatus · · Score: 5, Funny

    Old news, from last year.

  6. Re:Highlights problem with ntp... by thehickcoder · · Score: 5, Insightful

    Actually, if you where doing high precision scientific applications, it seems this type of behavior would be preferred. Because of the leap second there was not 2 seconds between 11:59:59 and 12:00:01 last night. So, using the NTP behavior if I want a timestamp that was exactly 10000000 seconds ago, I get one that represents 10000000 actually elapsed seconds.

    Just because everybody agrees to change their clocks doesn't mean time actually slows down or speeds up.

  7. It's not the 'ephemeris second' that's the problem by Jonathan+McDowell · · Score: 5, Informative

    Original poster is slightly wrong - it's not the length of the 1900 ephemeris second,
    it's the fact that the Earth, like all of us, is getting older and slowing down, so that
    the 2005 "Earth rotation" second (i.e. 1/86400 of one spin of the Earth) is longer than
    the 1900 equivalent and longer than the atomic time (SI) second. Instead of changing
    the length of the second, it is currently deemed less painful to keep using the old
    length and stick in an extra second every now and again.

    Since this depends on the slop of the Earth's interior, it's not a fully regular and predictable thing - we might even have to remove a second one year.

  8. Log of Atomic GPS Clock adjustment by BiggRanger · · Score: 5, Interesting

    I did up a project on sourceforge.net a few years back to sync my computers with a GPS http://atomicgpsclock.sourceforge.net/. Below is a log of the activity, normally there is a +/- 0.016 or so second instability, but 18:59:59 EST (or 23:59:59 UTC) the Navy made a 1 second adjustment to the GPS system, and it's vibible in the log at the next scheduled sync (in bold)

    2005.12.31 18:33:49 00032 GPS Status - Tracking: 3D
    2005.12.31 18:43:27 00020 Offset: 000.016 Buffer: 13
    2005.12.31 18:43:27 00032 GPS Status - Tracking: 3D
    2005.12.31 18:43:49 00020 Offset: -000.031 Buffer: 13
    2005.12.31 18:43:49 00032 GPS Status - Tracking: 3D
    2005.12.31 18:45:15 00033 GPS Status - Tracking: No
    2005.12.31 18:45:34 00032 GPS Status - Tracking: 1D
    2005.12.31 18:46:48 00033 GPS Status - Tracking: No
    2005.12.31 18:46:52 00032 GPS Status - Tracking: 3D
    2005.12.31 19:01:43 00033 GPS Status - Tracking: No
    2005.12.31 19:01:55 00032 GPS Status - Tracking: 1D
    2005.12.31 19:03:45 00020 Offset: 001.016 Buffer: 13
    2005.12.31 19:03:45 00032 GPS Status - Tracking: 2D
    2005.12.31 19:13:45 00020 Offset: -000.016 Buffer: 13
    2005.12.31 19:13:45 00032 GPS Status - Tracking: 3D
    2005.12.31 19:23:43 00020 Offset: 000.000 Buffer: 13
    2005.12.31 19:23:43 00032 GPS Status - Tracking: 3D
    2005.12.31 19:33:43 00020 Offset: 000.000 Buffer: 13
    2005.12.31 19:33:43 00032 GPS Status - Tracking: 3D
    2005.12.31 19:43:30 00033 GPS Status - Tracking: No
    2005.12.31 19:43:40 00032 GPS Status - Tracking: 1D
    2005.12.31 19:53:41 00020 Offset: -000.031 Buffer: 13
    2005.12.31 19:53:41 00032 GPS Status - Tracking: 3D
    2005.12.31 20:03:39 00020 Offset: 000.000 Buffer: 13
    2005.12.31 20:03:39 00032 GPS Status - Tracking: 3D