Happy Leap Second!

[kengr]

(I'm posting this about 30 minutes late. Ooops.

The leap second was 23:59:60 GMT Or 15:59:60 PST.

So your day has been one second longer. Hope you made good use of it.

Comments

[gridlore.livejournal.com]

I played the Minute Waltz at sixty times normal speed.

[fayanora.livejournal.com]

Wow, wtf humans?

[kengr]

Atomic clock time is very accurate. The earth's rotation is slowing down. So, to keep astronomical time in synch with atomic clock time, evey once in a while, they add a leap second. It's been 3 years since the last once, but it's possible to have two in the same year if earth's rotation changes fast enough.

Currently, they are only inserted as 23:59:60 (between 23:59:59 and 24:00:00) on the last day of June or December.

There are provisions for adding them at the end of other months, and for *subtracting* seconds if something causes a speed up (in that case time would go 23:59:58 24:00:00)

The time signals some clocks and watches get via shortwave and the time signals you can get from the net if you install the right program contain encoded data giving advance warning of a leap second several weeks in advance. :-)

[fayanora.livejournal.com]

Does the earth's rotation ever speed up? I'm kind of a little worried to hear that it slows down.

[kengr]

Long term, it's just gonna keep slowing down. It might speed up tiny bits occasionally, but it's gonna keep slowing down.

Not long after the formation of the moon, the days was something like 10 hours long. The slowing down is mostly due to tidal drag from the moon.

The tides dragged the moon's rotation into a tidal lock with Earth a long time ago. Meanwhile, the drag is converting angular momentum from the Earth's rotation into orbital angular momentum for the Moon.

So as the Earth slows down, the moon spirals farther out.

Some time, far, far in the future, the Moon will be a lot farther away and the Earth will rotate once a month (so the moon will stay in the same place in the sky as seen from any point on Earth)

But that is quite a few billion years off.

[fayanora.livejournal.com]

But that is quite a few billion years off.

Phew! And who knows, if humans or something evolved from them are still alive and technologically advanced, maybe they'll be able to correct things back to 24 hour days.

Oy, that's a BIG if.