This year, we all get an extra second on June 30

Story highlights

  • A "leap second" will be added to the world's standard time on June 30
  • The move is to keep clocks in sync with the Earth's rotation

(CNN)This is going to be a long year. Well, one second longer.

We're all going to get an extra tick of the clock, known as a "leap second," on June 30.
    The bonus sliver of time raises a couple of questions.
      How to spend that extra second? Sleeping? Working? Maybe Facebook's Mark Zuckerberg will use it to help keep up with his New Year book-reading program.
      Then there's the question of why we need to tinker with clocks all around the world in the first place.
      Earth vs. atomic clocks
      It all comes down to physics, according to Nick Stamatakos, the head of Earth Orientation Parameters at the U.S. Naval Observatory, which oversees atomic clocks in the United States.
      "The real simple explanation is the Earth is slowing down a little bit," he told the Australian Broadcasting Corporation.
      That means atomic clocks are keeping more accurate time than our planet's own rotation, which can speed up and slow down because of tides and changes within the Earth's core.
      To get things back in sync, an extra second is periodically added to Coordinated Universal Time (UTC), the world's benchmark time standard.
      The call is made by scientists at the International Earth Rotation and Reference Systems Service, the agency that keeps tabs on the spinning of the planet. It announced the decision to add a leap second this year in a bulletin Monday.
      The previous one was in 2012, but that didn't go entirely smoothly. Some of the software platforms that underpin a lot of websites didn't know how to cope with the extra second.
      U.S. wants to ditch leap seconds
      The issue has become an international sticking point.
      Some countries, including the United States, want to get rid of leap seconds altogether, saying they're too disruptive to precision systems used for navigation, communication and other services.
      But others, like Britain, have argued that it's risky to allow a divergence between the time kept by atomic clocks and that of the Earth's rotation.
      An international radiocommunication conference in 2012 put off a decision on the matter until this year.
      In any case, fewer leap seconds are being added nowadays than a few decades ago.
        "Earth isn't as slow as it was in the 70s," said Stamatakos. "Relative to the 1970s, it's sped up a little bit."
        But still not enough to keep time with the atomic clocks.