Warning! Time Stops on Tuesday


With the advent of ever-more-accurate clocks, keeping good time is becoming surprisingly complicated. (Nat Geo News)

Teachers, scroll down for a quick list of key resources in our Teachers’ Toolkit, including today’s MapMaker Interactive map—and a round-up of other interesting reads this week.

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Note: Current Event Connections is slowing down for the summer. Our column will continue to appear once or twice a week until mid-August. If you have an idea for a Current Event Connection, a recommendation for a good read, or want to share one of your MapMaker Interactive maps, let us know in the comments!


Discussion Ideas

  • Watch the short Nat Geo video above. What is a leap second?
    • Leap seconds are seconds added to official timekeepers to keep the time we use (on our watches, clocks, computers, and other devices) closely in sync with the actual rotation of the Earth.


  • Why does time need be adjusted?
    • Earth is a pretty dynamic place, and natural events such as earthquakes and volcanoes change the speed of the Earth’s rotation “ever so slightly” every year, according to the Nat Geo video.


  • Are leap seconds added every four years, like leap years?
    • Nope. Leap seconds are added whenever the Earth’s rotation changes by .9 second. This can be once every couple of years, or several times in a shorter period. According to Nat Geo News, “in the early 1980s, time scientists were adding them every year.”



  • Satellites of the Global Positioning System uses time to calculate locations. Will the GPS navigation on your smartphone or in your car be impacted by the leap second?
    • Nope. According to Nat Geo News, “true GPS time is off from civilian time by something like 16 seconds . . . Navigation services . . . like GPS never use leap seconds. . . because they need accurate measures of time in their calculations. If they stopped their internal clocks for the leap second, they would get inaccurate positions. The end-user isn’t aware of this because the GPS system will still send information to the receivers we use . . . about the leap second.”



Nat Geo: Why Time Will Stop For a Leap Second

Nat Geo: Time Stops! For a leap second . . . map




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