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Longest Running Thread EVER


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Re: Longest Running Thread EVER

 

On May 5 one year I was lecturing to my solar system astronomy class, and quite by accident we were covering the surface features of Venus. Among these are some large, odd, round features called coronae; some have speculated that they are the result of a convection-cell upwelling in the planet's mantle that got to the (thin, weak) crust and buckled it in a more-or-less round pattern several hundred km across.

 

At one point in the middle of the lecture I looked up into the class (this was in the large, steeply-raked lecture hall, about 200 students in the class) and said, apropos nothing, "Somehow it seems appropriate to discuss Coronas on Cinco de Mayo."

 

There was no reaction that I picked up.

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Re: Longest Running Thread EVER

 

Similarly, I get very few reactions to my statement, "Tidal locking is the final absolution of original spin," too. A few more rueful head-shakings here at the Jesuit university (where there's the theology requirement) than at the state universities, but fewer than I would have guessed.

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Re: Longest Running Thread EVER

 

It's a pun on Original Sin. Despite that, it's valid scientifically.

 

None of the moons in the Solar System and very few of the planets currently rotate at the same speed as when they were newly formed, 4.5 Gyr ago. Tides from their nearby neighbors raise bulges; when a planet rotates at a different rate than the bulge, then there's continuous flexing of the planetary material as it rises and relaxes from the tidal pull. That causes friction, and the frictional heating converts the rotational kinetic energy of the body into heat. The end state, when no more energy is dissipated, is "tidal locking", where the rotation period or the body is the same as the orbital period of the body making the tides; in such a case the body has one face permanently locked to face the other (as is the case for Earth's Moon). It's an important process in the dynamical evolution of a planetary system.

 

As a result, the initial rotation ("original spin") is slowed, and ultimately is removed in the final tidally-locked state. Use of the word "absolution" serves to amplify the pun's effect.

 

I know, I know ... :rolleyes:

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Re: Longest Running Thread EVER

 

Just make sure it won't pop the circuit breaker your 'puter is on.

 

(This is a perennial problem at home ... the clod who did the wiring extended the kitchen sockets line down into the basement, which is where the gaming table and computers are. It gets cold down there. So we have a space heater. But if you run the space heater and the microwave oven upstairs at the same time, POP! And the computers are on the same circuit. Grr.)

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