New Horizons at Pluto

phunk said:
I've heard "sharon", "charon", and "karon" and have no idea which is correct.
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It all depends on your definition of "correct." The dictionary pronunciation is "kha-ron" after the ferryman in Greek mythology. According to Wikipedia the moon was named Charon by its discoverer, James Christy after his wife's nickname, "Char."
NASA has apparenly adopted the "Sharon" pronunciation as an institutional inside joke.

"There is minor debate over the preferred pronunciation of the name. The practice of following the classical pronunciation established for the mythological ferryman Charon (IPA [ˈkɛ:rən]) is used by major English-language dictionaries, such as the Merriam-Webster and Oxford English Dictionary.[13][14] These indicate only one pronunciation of "Charon" when referring specifically to Pluto's moon: with an initial "k" sound. Speakers of many languages other than English, and many English-speaking astronomers as well, follow this pronunciation.[15]" Wikipedia.

No one seems to call the moon "Charon."
 
Skeptic Ginger said:
Oh good grief!

Like that made a difference in the context of the issue at hand. :rolleyes:

OK then, the Moon is tidally locked and you don't see significant heating.:cool:

It's one thing to clarify an issue, I like learning something as much as the next guy. But there was no reason to post like it was a pissing contest.
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No offence intended.
 
Skeptic Ginger said:
There are so many other icy bodies out there, wouldn't some of the others experience the same melting?

And Pluto rotates every 6 hours, making it harder for solar heating to build up.
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Wonder what that rotation does to the ice. It's not the strongest material in the world, and I'm sure the forces involved have to have SOME effect on it.

Elagabalus said:
Not sure why they keep showing that "amazing" Hi-Res image of Hydra:
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It's the best we've got.
 
jhunter1163 said:
I've always pronounced Charon "Karen", like Karen Valentine, because I read in a book somewhere that that was the correct pronunciation. I may, of course, be entirely wrong.
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I always thought it was "chair-on" as in "put the chair on the floor".
 
Dinwar said:
Wonder what that rotation does to the ice. It's not the strongest material in the world, and I'm sure the forces involved have to have SOME effect on it.
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Pluto rotates every six days, not every six hours. So there's not much effect.

Now, Haumea, on the other hand...
 
Ziggurat said:
Pluto rotates every six days, not every six hours. So there's not much effect.
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Over a few million years small effects accumulate. It may not even be direct effects--could be that the rotation introduces a small force, which can be seen as a slight tendancy for things to move in one direction.

I'm not saying "I'm right, you're wrong"; rather, I'm trying to think this through. In geology, even minor forces have a tendancy to build up to mountains and continents.
 
Whoops, six days then.

From 2002: Global warming on Pluto
Though Pluto was closest to the Sun in 1989, a warming trend 13 years later does not surprise David Tholen, a University of Hawaii astronomer involved in the discovery. ...

Elliot said the Aug. 20 occultation was the first that allowed such a deep probing of the composition, pressure and the always-frigid temperature of Pluto's atmosphere, which ranges from -391 to -274 degrees Fahrenheit (-235 to -170 degrees Celsius).
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Doesn't sound like solar heating could significantly melt the surface.
 
Skeptic Ginger said:
Doesn't sound like solar heating could significantly melt the surface.
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Depends on a few factors, such as composition and the presence of other heat sources. Maybe radioactivity heats it to JUUUUUST under melting, then the Sun adds the last few calories?
 
Dinwar said:
Over a few million years small effects accumulate. It may not even be direct effects--could be that the rotation introduces a small force, which can be seen as a slight tendancy for things to move in one direction.
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Gravity is much stronger (even on Pluto).

Simple calculation for g on the surface is Gm/r^2 = 0.74m/s^2 (about 7.5% earth gravity).
Local correction for rotation on the equator = v^2/r = 1.4x10^-4 m/s^2. So we can basically ignore any static component here on the basis that it's less than the margin of error in our measurement of g anyway.

Now if there were a dynamic component (such as tidal interactions), then things would be more interesting.
 
Dinwar said:
Over a few million years small effects accumulate. It may not even be direct effects--could be that the rotation introduces a small force, which can be seen as a slight tendancy for things to move in one direction.
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Sure. We should expect Pluto to be ever so slightly oblate as a result of rotation. Once equilibrium oblateness is obtained, there should be no resulting net forces.

But that oblateness is probably less than Earth's. I brought up Haumea because that's an example where the equilibrium oblateness is very significant.
 
Dinwar said:
Depends on ... the presence of other heat sources. Maybe radioactivity heats it to JUUUUUST under melting, then the Sun adds the last few calories?
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Given that would make solar heating only secondary to internal heat sources it seems a stretch to then say solar heating resurfaced the ice.

Don't you think this exercise of attributing the resurfacing to solar heating to be getting just a bit silly, or perhaps anal?
 
The Mordor region on Charon looks like it is a depression, with the dark material coating it like dust. Could it be a large, shallow crater filled with debris?
 
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