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banquo's_bumble_puppy
2011-Feb-28, 05:40 PM
Has Io likely always been volcanically active? I think I read somewhere that it has turned itself inside-out at least once. Will the moon eventually evaporate? It has a heat source; would any water on the surface long since have left?

Hungry4info
2011-Feb-28, 07:31 PM
Has Io likely always been volcanically active? Perhaps. It would have started once it got caught in resonance with Europa, which was probaby very early on.


Will the moon eventually evaporate? No. It just keeps resurfacing itself.


would any water on the surface long since have left?I think so. AFAIK, there's no water on Io, in stark contrast to the other large moons of Jupiter.

Ara Pacis
2011-Feb-28, 10:01 PM
...it has turned itself inside-out at least once.

So, all the sulfur that is on the outside was once in the core while the heavier materials were above it? That doesn't sound physically plausible.

Romanus
2011-Mar-01, 12:35 AM
I saw a reference to an old paper in which the authors calculated that Io *may* go through alternating periods of millions of years of enhanced and suppressed volcanic activity, no doubt due to long-term resonance variations.

So, all the sulfur that is on the outside was once in the core while the heavier materials were above it? That doesn't sound physically plausible.

More likely, the sulfur was evenly-distributed throughout the initial materials, but was steadily concentrated in the upper, more active layers--befitting a low-melting point substance, just as Earth's crust has a more silica-rich composition than the mantle or core.

Addendum: Of course, sulfur is also much less dense than silica (s.g. ~2.0 to 2.6).

John Jaksich
2011-Mar-03, 05:41 AM
So, all the sulfur that is on the outside was once in the core while the heavier materials were above it? That doesn't sound physically plausible.

According to the data that I have is that Io is the most dense of the Galilean moons---at ~ 3.6 g/cc----> grams per cubic centimeter and may possess a very thin atmosphere of sulfur dioxide.

Io has the following composition
Crust, silicate, & sulfur
upper Mantle, molten
lower Mantle, solid or molten
Core--Iron rich

The volcanic activity is supposedly--more silicate than sulfur--

The sulfurous-type coloration is misleading because that compound is the least dense and is more likely to be seen by astronomers.


And let me quote from the text:

Io--is known for the Sulfurous compounds are the most volatile; so due to the tidal heating account for the silicate eruptions from underneath the crust.

For anyone interested I am taking my data from the text by Gunter Faure and Teresa Mensing---who are (both) at The Ohio State University system--(different campuses).

Text:
Introduction to Planetary Science---The Geological Perspective


The publisher is Springer

Year:
2007

Pages: 297--311

Ara Pacis
2011-Mar-03, 08:22 PM
I'm only disputing the idea that Io turned itself inside out, not the mechanics of Io's volcanism. The OP seemed to suggest that the turning itself inside out was to be taken literally.

Ilya
2011-Mar-03, 08:41 PM
Since all of Venus' surface seems to be no more than 500 million years old, Venus had also "turned itself inside out", possibly more than once. All of Venus' original crust has descended and melted. But that's just upper mantle cycling. Core remains core, and I am sure at no time did Venus (or Io) have heaviest elements on top of the lightest ones.

Ara Pacis
2011-Mar-03, 10:01 PM
Since all of Venus' surface seems to be no more than 500 million years old, Venus had also "turned itself inside out", possibly more than once. All of Venus' original crust has descended and melted. But that's just upper mantle cycling. Core remains core, and I am sure at no time did Venus (or Io) have heaviest elements on top of the lightest ones.

My point exactly.

John Jaksich
2011-Mar-04, 07:33 PM
I am under the impression (possibly mistaken?) Io's dynamics and the dynamics of Venus are different ---point is that (I thought I had made my point somewhat(?) clear)---the data I believe is currently correct is that Io's dynamics is better understood than Venus' and differentiation did take place on Io whereas with Venus (it is still up for debate) circa 2006 - -- 2007

John Jaksich
2011-Mar-04, 07:44 PM
Has Io likely always been volcanically active? I think I read somewhere that it has turned itself inside-out at least once. Will the moon eventually evaporate? It has a heat source; would any water on the surface long since have left?

As for H2O----there is none as is currently known.