December 29, 2016
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This is our best guess scenario of what the interiors of the four Galilean moons of Jupiter look like. Callisto Diameter 4821 km (2,995 miles) Mass (1.075938±0.000137)×1023 kg (0.018 Earths) Mean Density 1.8344±0.0034 g/cm3 |
Pluto Diameter is 2374±8 km (1473 miles) Mass is (1.303±0.003)×1022 kg, 17.7% of the Moon Mean density is 1.860±0.013 g/cm3 |
Taking the low range density of Callisto and high range density of Pluto produces this.
Callisto = 1.8378,
Pluto = 1.847
Their densities are really close, nearly identical.
Callisto = 1.8378,
Pluto = 1.847
Their densities are really close, nearly identical.
Here's a quote from Wikipedia about Callisto.
Callisto is the largest object in the Solar System not to be properly differentiated. It is not in an orbital resonance like the three other Galilean satellites--Io, Europa, and Ganymede—and is thus not appreciably tidally heated. Callisto's rotation is tidally locked to its orbit around Jupiter, so that the same hemisphere always faces inward; Jupiter appears to stand nearly still in Callisto's sky.
Callisto is composed of approximately equal amounts of rock and ices, with a density of about 1.83 g/cm3 The surface of Callisto is the oldest and most heavily cratered in the Solar System. Its surface is completely covered with impact craters. It does not show any signatures of subsurface processes such as plate tectonics or volcanism, with no signs that geological activity in general has ever occurred, and is thought to have evolved predominantly under the influence of impacts.
Callisto is thought to have formed by slow accretion from the disk of the gas and dust that surrounded Jupiter after its formation. Callisto's gradual accretion and the lack of tidal heating meant that not enough heat was available for rapid differentiation. The slow convection in the interior of Callisto, which commenced soon after formation, led to partial differentiation and possibly to the formation of a subsurface ocean at a depth of 100–150 km and a small, rocky core.
end quote
Pluto and Callisto's densities are nearly identical yet Callisto's diameter (4821 km, 2,995 miles) is about twice the size of Pluto (2374 km, 1473 miles). At twice the size Callisto has twice the surface gravity of Pluto. Which gives it two times as much chance of differentiating its core. Callisto is assumed to be non differentiated and is geologically dead displaying the largest number of impacts of any body in our solar system but Pluto is assumed to be differentiated and is obviously active. The rationale for saying Callisto is not differentiated is that;
Callisto's gradual accretion and the lack of tidal heating meant that not enough heat was available for rapid differentiation.)
Callisto's surface with all its impacts has not been refreshed by any geological processes.
Pluto has no apparent tidal heating or stretching is half the size of Callisto and is supposed to be radioactively hot after four billion years even though Callisto is not. A cup of hot water will cool faster than a bowl twice its size and the same would hold true for radioactively decaying material. How is Callisto at twice the size of Pluto with the same density not differentiated with a hot core creating geological activity while Pluto does. Callisto developed at temperatures around 100K while Pluto developed at temperatures around 40K. Pluto's smaller and colder than Callisto yet its supposed to be internally hotter. There must be something else at play here.
I still can't get my head around this theory that Pluto is radioactively hot creating all this geologic activity. Why isn't Callisto at twice the size of Pluto with basically the same conditions (no tidal stretching energy) not geologically active if a density of 1.86 is all that's required to have a hot radioactive core?
Pluto does have some small resonant pulses occurring. It's four small moons have resonant frequencies. While they are small and far away they do align and pulse at intervals. Pluto is in a 2:3 resonant zone with Neptune along with many other bodies like 1994 JR1. Excerpt from a NASA paper.
because the close approach distance is variable, Pluto’s perturbation on JR1 is effectively chaotic. While this could be described as Pluto quasisatellite (a quasi moon) behavior (and has: de la Fuente Marcos & de la Fuente Marcos 2012), since JR1’s orbit is still primarily controlled by Neptune, a more precise description would be a series of periodic Pluto scattering events, one of which JR1 is currently experiencing. Regardless of semantics, JR1 is certainly a case of Pluto exerting its gravitation influence over a fellow 3:2 resonant object.
If Pluto is exerting its gravitational influence over a fellow 2:3 resonance object then those fellow objects must be periodically doing the same thing to Pluto/Charon. Seems to me there are too many opportunities for Pluto/Charon to encounter objects which could induce a pulse or tidal flex or collision to rule this out and simply say there is a hot core and this hot core is the sole source of Pluto's geological activity.
If one is not inclined to accept the 4 billion year old collision theory of Pluto/Charon then another potential picture can be painted.
One to two billion years ago, while Pluto was wandering the solar system as a lone planet Neptune pushed another group of 2:3 resonant objects near enough to Pluto to initiate a spiral dance. One of these objects was Charon. The others were Charon's smaller satellites. When Charon and Pluto began their extreme elliptical orbits, Charon's smaller satellites were flung away but not completely out of range they were perturbed but not ejected.
Pluto and Charon experienced strong tidal stretching for a long period before their orbits settled into a quiet circular pattern. Eventually the smaller satellites began returning to a tighter orbit which caused them to collide with Charon and Pluto this is what created the impact at Mordor. The tidal stretching between Pluto/Charon caused both planets to warm and softening their underbellies. While the returning smaller satellites pounded Charon and possibly Pluto creating massive fractures causing the warmed subsurface fluids to flow onto the surface.
I don't have the tools or ability to prove any of this through modeling but if I did, I'm sure I could create a model that supports this scenario. That's my point about models. If you can conceive it, you can model it. And just because you can model it, that doesn't necessarily make it a correct concept.
Callisto is the largest object in the Solar System not to be properly differentiated. It is not in an orbital resonance like the three other Galilean satellites--Io, Europa, and Ganymede—and is thus not appreciably tidally heated. Callisto's rotation is tidally locked to its orbit around Jupiter, so that the same hemisphere always faces inward; Jupiter appears to stand nearly still in Callisto's sky.
Callisto is composed of approximately equal amounts of rock and ices, with a density of about 1.83 g/cm3 The surface of Callisto is the oldest and most heavily cratered in the Solar System. Its surface is completely covered with impact craters. It does not show any signatures of subsurface processes such as plate tectonics or volcanism, with no signs that geological activity in general has ever occurred, and is thought to have evolved predominantly under the influence of impacts.
Callisto is thought to have formed by slow accretion from the disk of the gas and dust that surrounded Jupiter after its formation. Callisto's gradual accretion and the lack of tidal heating meant that not enough heat was available for rapid differentiation. The slow convection in the interior of Callisto, which commenced soon after formation, led to partial differentiation and possibly to the formation of a subsurface ocean at a depth of 100–150 km and a small, rocky core.
end quote
Pluto and Callisto's densities are nearly identical yet Callisto's diameter (4821 km, 2,995 miles) is about twice the size of Pluto (2374 km, 1473 miles). At twice the size Callisto has twice the surface gravity of Pluto. Which gives it two times as much chance of differentiating its core. Callisto is assumed to be non differentiated and is geologically dead displaying the largest number of impacts of any body in our solar system but Pluto is assumed to be differentiated and is obviously active. The rationale for saying Callisto is not differentiated is that;
Callisto's gradual accretion and the lack of tidal heating meant that not enough heat was available for rapid differentiation.)
Callisto's surface with all its impacts has not been refreshed by any geological processes.
Pluto has no apparent tidal heating or stretching is half the size of Callisto and is supposed to be radioactively hot after four billion years even though Callisto is not. A cup of hot water will cool faster than a bowl twice its size and the same would hold true for radioactively decaying material. How is Callisto at twice the size of Pluto with the same density not differentiated with a hot core creating geological activity while Pluto does. Callisto developed at temperatures around 100K while Pluto developed at temperatures around 40K. Pluto's smaller and colder than Callisto yet its supposed to be internally hotter. There must be something else at play here.
I still can't get my head around this theory that Pluto is radioactively hot creating all this geologic activity. Why isn't Callisto at twice the size of Pluto with basically the same conditions (no tidal stretching energy) not geologically active if a density of 1.86 is all that's required to have a hot radioactive core?
Pluto does have some small resonant pulses occurring. It's four small moons have resonant frequencies. While they are small and far away they do align and pulse at intervals. Pluto is in a 2:3 resonant zone with Neptune along with many other bodies like 1994 JR1. Excerpt from a NASA paper.
because the close approach distance is variable, Pluto’s perturbation on JR1 is effectively chaotic. While this could be described as Pluto quasisatellite (a quasi moon) behavior (and has: de la Fuente Marcos & de la Fuente Marcos 2012), since JR1’s orbit is still primarily controlled by Neptune, a more precise description would be a series of periodic Pluto scattering events, one of which JR1 is currently experiencing. Regardless of semantics, JR1 is certainly a case of Pluto exerting its gravitation influence over a fellow 3:2 resonant object.
If Pluto is exerting its gravitational influence over a fellow 2:3 resonance object then those fellow objects must be periodically doing the same thing to Pluto/Charon. Seems to me there are too many opportunities for Pluto/Charon to encounter objects which could induce a pulse or tidal flex or collision to rule this out and simply say there is a hot core and this hot core is the sole source of Pluto's geological activity.
If one is not inclined to accept the 4 billion year old collision theory of Pluto/Charon then another potential picture can be painted.
One to two billion years ago, while Pluto was wandering the solar system as a lone planet Neptune pushed another group of 2:3 resonant objects near enough to Pluto to initiate a spiral dance. One of these objects was Charon. The others were Charon's smaller satellites. When Charon and Pluto began their extreme elliptical orbits, Charon's smaller satellites were flung away but not completely out of range they were perturbed but not ejected.
Pluto and Charon experienced strong tidal stretching for a long period before their orbits settled into a quiet circular pattern. Eventually the smaller satellites began returning to a tighter orbit which caused them to collide with Charon and Pluto this is what created the impact at Mordor. The tidal stretching between Pluto/Charon caused both planets to warm and softening their underbellies. While the returning smaller satellites pounded Charon and possibly Pluto creating massive fractures causing the warmed subsurface fluids to flow onto the surface.
I don't have the tools or ability to prove any of this through modeling but if I did, I'm sure I could create a model that supports this scenario. That's my point about models. If you can conceive it, you can model it. And just because you can model it, that doesn't necessarily make it a correct concept.
