Did New Year’s Eve seem a little longer than usual last week?
It should have because 1 second was added to that day, a so-called leap second.
This is just like the extra leap-day added to February during a leap year except a lot tinier.
So why is this done?
This is done to reconcile the two primary ways we humans measure time in terms of days and years.
One is ancient and low-tech…namely the spin of the Earth and it’s rotation around the sun. This is often referred to as solar time or astronomical time. The other is hi-tech and has been around since the 1950’s…namely atomic time using atomic clocks.
The problem is, these timepieces are diverging because the spin of the earth is slowing down by about 2 thousandths of a second a day while atomic clocks are accurate to less than a billionth of a second a day.
The spin of the earth is slowing down for multiple reasons, including the presence or absence of snow at the poles, solar wind, magnetic storms, and even space dust. The biggest contributor though is something called tidal braking. As the moon and earth’s tidal bulge pull on each other, our rotational friction is increased, which lengthens our days. In fact, back in the day, our day used to be much less than a day (10 hours long in fact).
The bottom line is that every 500 days or so, the discrepancy between solar time and atomic time adds up to about a second. This is when the International Earth Rotation and Reference Systems Service, in Frankfurt, steps in. They’re in communication with 50 national laboratories that collectively run about 300 atomic clocks. These clocks together create a weighted average that is much more stable than just one of the atomic clocks could be. This weighted time is then adjusted by leap seconds to determine what is called UTC or Coordinated Universal Time. UTC has replaced GMT or Greenwhich Mean time for people in need of absolutely precise timing. In fact, UTC is broadcast around the planet as the world’s official clock.
I’d love to see the email they send:
Dear Atomic clock people, here we go again…please stop your clocks for 1000 milliseconds…
As fascinating as this is, is this really worth it though?
Geoff Chester, a spokesman for the United States Naval Observatory has said:
“It’s an aesthetic thing more than anything…Life wouldn’t end if we eliminated the leap second.”
So what are the downsides?
Obviously, many digital products depend on precise timestamps like ATMs and Internet network protocols.
What I didn’t know was that leap seconds can crash cell phones and GPS devices if they aren’t programmed to expect them. This is difficult to do since these rogue seconds come at unpredictable intervals.
Chester has even said that “Leap seconds turn out to be more of a pain in the neck than Y2K ever was”
So much so that the International Telecommunications Union which is part of the United Nations, wants to do away with the leap second, perhaps replacing it with a leap minute every century or so.
Other experts have said that this is just putting off the problem for the next century and that a full minute would be an intolerable duration. Astronomers are ticked-off because they’d have to re-write tons of software to remove leaps seconds.
As for me? I like them because they’re fun to talk about since they lead into so many fascinating scientific tangents.