Postpone That Celebration

[RoadDog]

Attention all road wanderers and road travellers across this great country!!

You are going to have to wait one extra second to start your New Year's celebratory libations. Again, do NOT start at the stroke of midnight whether you're on the road (if so, pull over and you shouldn't be drinking there anyway) or stationary at some Roadhouse.

For the new year 2006, we are going to have a leap second, the 23rd time since 1972. The last leap second was seven years ago. That means we are going to have to wait one more second.

The reason for these leap seconds are the modern atomic clocks which are extremely accurate. The problem is that our old earth's rotation is inconsistent. It has actually been slowing down. Could this be some repercussion of the Greenhouse Effect?

Wishing everyone a very happy New Year and Keep on Down those Two Lane Highways. ---- RoadDog

[Robert Schaller]

Naw, not the greenhouse. It's just that after 5 Billion years or so, the old Earth is getting a bit tired! Happy New Year to all! Bob

[AZBuck]

To be correct, the Earth's rotation is gradually slowing down because we have a moon. The Earth's rotational energy is gradually being transferred to the Moon's orbital energy because of tidal interactions. As the Earth slows down, the Moon is moving farther away from the Earth. BTW - you all are living in a unique period of the Earth-Moon-Sun dance. Right now, both the Moon and the Sun look to be about the same size in the sky (about 1/2 degree) so we can experience one of the heaven's greatest shows: total eclipses. As the Moon moves farther away, it will gradually appear smaller in the sky and will no longer completely cover the Sun during an eclipse.

AZBuck

[PNW Judy]

That's fascinating, AZBuck! Thanks.

[RoadDog]

A person just has to wonder how AZbuck knows so much about this stuff. Inquiring minds want to know.

[RoadTripper Brad]

Are you sure about that Buck... If I recall correctly, the earth was slowing because the moon was moving away, rather than the moon moving away because the earth is slowing... that's what all my studies have told me.

[AZBuck]

Brad,

Note that I did not say that one caused the other. I simply said that energy was being transferred from one to the other. It's a subtle but important distinction. As someone once said of Ginger Rogers' dancing, she had to do everything Fred Astaire did, but backwards and in heels.

AZBuck

[Dan K]

At the risk of being ignorant again, I've always wondered why the extra second can't be somewhere else in the year besides 12/31. Is it because that's the most obvious one and nobody will miss it? How many people have their clocks exactly in tune with the earth anyway? Do people know exactly when midnight arrives local time or do they watch tv to see the actual countdown?

I assume the extra second must have come early in the day, maybe when the Pacific time zones passed midnight, since I did not see it in New York, and we can't have one for each time zone, otherwise there would be 24 extra seconds.

Dan

[AZBuck]

How many people have their clocks exactly in tune with the earth anyway?

Well, consider the GPS satellites. In 1 second they move about 10 miles and since position is relative, if that leap second wasn't taken into account, the position your handheld unit gave you would be off would be about the same size - more than the acceptable meter scale inaccuracy. But mostly it's of interest to astronomers. Mars moves 15 miles in that second, Mercury moves 30 miles. The people who have to worry about such differences are few, but the consequences of ignoring it can be huge. Consider the Austrian and Russian offensive against France in the Napoleonic Wars. The Austrians used the Gregorian Calendar while the Russians used the older Julian Calendar. The two calendars differed in how they accounted for leap years and had been slowly drifting apart since the 16th century. When the Austrians showed up for battle at Austerlitz on Sept. 26, 1805, they expected the Russians to join them. The Russians showed up 12 days later when their calendar said it was the 26th. Napoleon won.

I assume the extra second must have come early in the day.

Actually, I'm pretty sure that it's added at midnight, New Year's, UTC (Universal Coordinated Time - what used to be known as GMT, or Greenwich Mean Time).

AZBuck

[Mark Sedenquist]

... but the consequences of ignoring it can be huge. Consider the Austrian and Russian offensive against France in the Napoleonic Wars. The Austrians used the Gregorian Calendar while the Russians used the older Julian Calendar. The two calendars differed in how they accounted for leap years and had been slowly drifting apart since the 16th century. When the Austrians showed up for battle at Austerlitz on Sept. 26, 1805, they expected the Russians to join them. The Russians showed up 12 days later when their calendar said it was the 26th. Napoleon won.

Yikes and I thought our logistics went awry sometimes. Thanks for the lesson!

Mark