A Year Half Gone- But With An Extra Second

I did not know that:

Today marks the 26th time a Leap Second will be added to the calendar.

In the second half of the 20th century, we started tracking time via atomic clocks, which happen to be more accurate and precise than the rotating Earth itself — our technology was better at keeping time than our planet was. This crossover allowed us to notice that Earth’s rotation rate is, in fact, slowing down.

The primary culprit here is the Moon, whose tidal forces on Earth create friction between the sloshing oceans and our north-south coastlines. In response, the Moon’s orbit is spiraling away from Earth at a rate of about 2-inches (4cm) per year.

Such is the layout of this cosmic ballet — choreographed by the forces of gravity.

Several other factors also influence Earth’s rotation, but can serve to either slow us down or speed us up. In all cases it involves the re-distribution of mass on Earth’s surface, changing our planets rotation properties. These includes the freezing and melting of glaciers, mass migrations of animals, the buildup of new dams, and earthquakes.

Three ways to accommodate this fact: 1) Ignore it altogether. 2) Redefine the length of the Second, as necessary, to keep the total number of seconds the same, no matter the length of the day. Or 3) intermittently add “leap” seconds to compensate.

If we did (1) then eventually, clock time will not make sense relative to what the Sun is doing. If we did (2) then all the measurements that now depend on the precise definition of the second would be cast into flux. So we choose option (3). Beginning in 1972, on June 30 or December 31 (or both) we’ve added 25 leap seconds, as necessary. Today is such a day.

Beginning in 1972, on June 30 or December 31 or both, we’ve added 25 leap seconds, as necessary. Today is such a day.

Leap Seconds appear in the final minute of the last hour of today, Greenwich Time. For the Eastern Time Zone (North America) this corresponds to 7:59 PM. That minute will have 61 seconds in it. Something I’ve celebrated each time with a very tiny bottle of champagne.

Whatever you do, don’t waste it.

As always, Keep looking up.

-Neil deGrasse Tyson, New York City

Not a waste at all. I spent it having a late dinner and talking with Eleanor about the good things of the day.

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On the other hand, I was aware of today bringing half of 2015 to a close.  I ended the outside part of it, right before that late dinner, by beginning a new set of fitness classes with a new group of trainers- invited by a friend I met in the last group (we're still both friends with the previous trainer, and she comes to these classes herself at times). It's a very intense mix of cardio (elliptical in my case still), rowing, and few but furious sets of both upper and lower body weight and core exercises.  You wear a heart monitor, which is tracked for the 56 minutes, and if you keep up (which I somehow did), you get close to a 1,000 calorie burn during the session and more to follow into even the next day.

It's corporate, but much more structured and less yakkity-yakkity than the previous classes had become. I'm in for at least the first two months of Happy Half Year, and we'll see where it goes from there.

I finished up a bunch of things for work today, and may have gotten out of a second road trip of the week tomorrow.  Most things here will be closed Friday, and the kids and grandkittehs are due that day as well.  I'll look forward to that even more than usual- after all, there's that extra second still to benefit from:)