Leap Second Mystery: Is Earth's Orbit Slowing?

[Jeebus]

Is this article incorrect to attribute the leap second to a slowing in the Earth's orbit?
I thought I understood this issue already, but as I tried thinking through this to prove to myself how the article was wrong I suddenly realized that I wasn't able to resolve the two degrees of freedom: the Earth's revolution around the sun, and the Earth's rotation. Leap days are designed to bring the year to an end at the same place in the Earth's orbit. Leap seconds are intended to keep midnight at the point in the Earth's rotation. Or at least that's what I thought. But how do leap days and leap seconds work together to make the year end happen at the same time of day every year (within the accuracy of the gross adjustments of leap days)? Am I just confused, or am I right in seeing the issue is a little more involved than I originally thought. And is the Earth's orbit really slowing? I was only aware of the slowing rotation.

Earth orbit slows no more, baffling scientists

BOULDER, Colorado (AP) -- In a phenomenon that has scientists puzzled, the Earth is right on schedule for a fifth straight year.

Experts agree that the rate at which the Earth travels through space has slowed ever so slightly for millennia. To make the world's official time agree with where the Earth actually is in space, scientists in 1972 started adding an extra "leap second" on the last day of the year.

For 28 years, scientists repeated the procedure. But in 1999, they discovered the Earth was no longer lagging behind.

At the National Institute for Science and Technology in Boulder, spokesman Fred McGehan said most scientists agree the Earth's orbit around the sun has been gradually slowing for millennia. But he said they don't have a good explanation for why it's suddenly on schedule.

Possible explanations include the tides, weather and changes in the Earth's core, he said.

The leap second was an unexpected consequence of the 1955 invention of the atomic clock, which use the electromagnetic radiation emanated by Cesium atoms to measure time. It is extremely reliable.

Atomic-based Coordinated Universal Time was implemented in 1972, superseding the astronomically determined Greenwich Mean Time.

Leap seconds can be a big deal, affecting everything from communication, navigation and air traffic control systems to the computers that link global financial markets.

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My hypothesis is that going off the top of my head for a first pass at this. The article is wrong.

• The leap second is associated with the slowing rotation of the Earth on it's axis NOT it's orbital motion through space.
  
• I also think that the leap second is NOT added during the last day of the year but rather is when needed.

Can you guys help?

 

[Evo]

Originally posted by Jeebus
Is this article incorrect to attribute the leap second to a slowing in the Earth's orbit? *snip*

My hypothesis is that going off the top of my head for a first pass at this. The article is wrong.

• The leap second is associated with the slowing rotation of the Earth on it's axis NOT it's orbital motion through space.
  
• I also think that the leap second is NOT added during the last day of the year but rather is when needed.

Can you guys help?

You are right. Here is more "accurate" info.

http://tycho.usno.navy.mil/leapsec.html