Mountains, Glaciers, possible Volcanoes on Pluto

The Giant Japanese Hornet

The Japanese Giant Hornet is one of the most vicious insects on Earth. It has a voracious appetite, is homicidal,  and is huge. It can be up to thirty to forty times larger than a bee. If it happens upon a European bee colony transplanted to Japan it will kill off the entire colony in a matter of hours.

But this is not what happens if the Hornet should discover a native Japanese bee hive. Apparently the Japanese bees have a solution to the giant hornet’s predatory violence. When the bees see a Hornet, they will retreat into their hive and slyly allow the Hornet to enter. Once the Hornet enters the Hive, the Japanese bees will attack the Hornet by enveloping the intruder. Hundreds of bees will surround the Giant Hornet and begin to vibrate their wings and bodies. As they do so, they cause the core temperature of the Hornet to rise dramatically, and eventually the Hornet dies.

They then erase any pheromone markers left by the Hornet, the hornet never returns to its nest,  and thus the bee hive is saved.

As we will see there is some similarity to the Plutonian satellite system, and is possibly one reason why there is geological activity on a world so far removed from the sun and so far removed from a giant planet.

New Horizons

The exploratory craft, New Horizons, after traveling for nine years through the vast empty void of space has recently revealed that Pluto and its largest moon Charon are not the frozen dead worlds imagined for so long, but instead are apparently geologically alive with large mountain ranges and a highly varied landscape. This has left most astronomers confused since they had for all this time expected to see a globe made of ice with little variation on the surface.

This expectation was supported by the idea that the only way small bodies like Pluto and Charon could have geological activity was if a giant planet squeezed them and thus deformed their surface. Being that  Pluto and Charon had no giant master near them, it would have been logical to assume that there could be no such surface deformation.

But there is. There are huge mountains on Pluto, and Charon too shows some kind of recent geological activity.  So what might be the cause?

Earth Moon System’s Core Heat

As we have mentioned many times before on HotCoreEarth, there is between a planet and a satellite a particular interaction which may be most responsible for geological activity and we have previously named this process a Layered Differential Rotation(LDR). We can also call it a Radial Differential Rotation since it is dependent on the distance between two masses, being planet and satellite.

The Earth Moon system will experience a particular type of Tidal interaction that does not stop at the surface of the Earth, but goes down to the core, and even throughout the entire diameter of the planet. We are used to thinking that tidal forces are evident only on bodies of water, like the ocean, but in reality tidal forces go far deeper into the Earth, and affect all kinds of material, including the crust made of minerals and rock. These tides will also affect the subsurface of the Earth as well. But what is crucial to understand here is that these tides are not everywhere on Earth the same. At the surface they will be stronger than at a deeper point heading towards the Earth’s core. The further away from the moon, the less the tidal interaction. So there is a difference in Lunar tidal energy experienced by the Earth.  Over many repetitions as the Moon orbits the Earth every twenty eight days, and over many revolutions of the Earth, as the Earth revolves around its polar axis every day, there will be a tensor stress built up. Meaning that the fabric of the Earth is going to be stretched at different points from along the diameter facing the Moon at any given time. This stretching will lead to both stress and friction. And is probably a leading, if not the sole cause of Earthquakes.

The Moon will tug on the crust and therefore slow it down relative to the subsurface, thus causing a differential rotation between the crust and mantle. This tidal differential will extend throughout the entire planet and will result in both deformation and in the heating of the core.

Speed of Rotation and Atmosphere

We should note that the faster the axial rotation of any given mass, the greater will be the effects of Layered Differential Rotation and the frictional stresses it causes.  It should also be noted that a thick atmosphere, or ocean-even frozen as ice- will probably tend to trap much of this heat released in core dynamics and tend to have more significant effects on the surface.

Volcanism and Seismic Activity on Pluto and Charon

This same exact process is probably active in the Pluto-Charon system. Only in Pluto and Charon the effects of this differential rotation will be far more acute and somewhat inverted since Charon is actually much closer to Pluto than is the Moon to the Earth, and is actually much larger relative to Pluto than is the Moon to the Earth.

Charon is only 12000 miles away from Pluto, and that makes its gravitational tug on Pluto far more severe than is the Moon’s tug upon the Earth. The force exerted on Pluto will be approximately eight times the force exerted on the Earth by the Moon.  Also, Pluto being a far smaller body than is the Earth, will be far more subject to tidal deformations than would be the Earth.

We should also note that while both Pluto and Charon orbit a center of mass external to either, their orbital period is only six days.  The angular velocity, and therefore the directional acceleration of the two bodies is far greater than the Earth Moon system. Though the Sun’s tug is minimal on the Plutonian system, unlike on Earth, still the large angular velocity of the Plutonian satellite system is bound to cause enormous centrifugal forces adding to the LDR.

Yet we should keep in mind here that the Earth  revolves around its own axis and has a much higher rotation than would Pluto and Charon which are tidally locked and revolving over a center of mass beyond the body of Pluto. Therefore the actual dynamics may  differ. But the differential speed effect will be present in both systems.

What we mean is that these two bodies, Pluto and Charon are circling each other so closely and so quickly that they are causing enormous tidal disturbances within their cores and this is the reason for the geological formations we see at the surface. The fact that they are circling a center of mass external to either body will also add additional dynamics-they are in effect pivoting over that center of mass and not merely rotating which will amplify the effect of any radial differential dynamics.

The nature of the differential rotation of the Plutonian system will also be in a different direction than that of the Earth-Moon system,  being that Pluto and Charon are tidally locked (they face each other constantly) and thus there is no independent  axial rotation of Pluto as there is on Earth-which is to say that Pluto does not rotate independently relative to Charon. The Earth’s daily rotation is much faster than is the orbital period of the Moon, and thus the tidal tug of the Moon tends to slow the crust down relative to the mantle. However, on Pluto the effect is the reverse as the surface of Pluto probably rotates faster than does the subsurface. There will be a tendency for material within Pluto and Charon to lag behind the crust, or surface layers. Much like taking a plastic ball filled with water and swinging it on a string will cause the liquid inside to rotate in a direction opposite to the orbital direction.  But the geological effects will be the same as with the Earth Moon system, although possibly more pronounced on Pluto’s surface since the main brunt of the differential force is coming from the surface of Pluto as it rams into the slower rotating lower layers-this would be especially true if they are hotter, and therefore more pliable than the frozen surface.

There will be arguments made that Pluto may be solid all the way down, unlike Earth which is made of molten rock and metals. But this would not really matter. The stress created by a layered differential rotation would be enough to cause sufficient friction over time so as to result in  both frictional heating, and also distortions on the surface and throughout the entire body of both Charon and Pluto. Eventually Tidal distortions caused by Charon, even on solid material, are going to cause a buildup of stress and friction. At some point in time these stresses will be released and friction will occur. This will result in heating throughout the globe of Pluto, and of Charon.

It’s very likely that both Pluto and Charon are subject to numerous earthquakes and quite possibly  to  extreme seismic violence. There is little doubt that the gigantic chasms found on Charon are due to that sort of tidal stress that builds up over time as the two bodies circle each other so closely in a relatively short period of six days.

Japanese Hornet Effect

Yet differential rotation is probably not the only effect of the Plutonian satellite system or for that matter on the Earth Moon system. Pluto has four other satellites besides Charon. And though Charon is the largest relative to Pluto it is probably not the only satellite creating frictional stresses on the Plutonian system.

The smaller satellites, Nix and Styx, Hydra and Kerberos are relatively insignificant to the mass of the Plutonian system as a whole, but they are still large bodies. Being twenty to thirty miles in length on average and another twenty miles in width makes them significant contributors to tidal forces since they are relatively near to the planet in comparison to the Moon which a quarter million miles away from Earth.

So even if these smaller satellites do not have the large tidal impact that Charon has on Pluto, they will have some impact. More importantly, the Tidal Wave interference between all these satellites will probably have a significant effect on the core temperature of Pluto and Charon.

Like the Japanese Hornet and the method used by Japanese bees to “cook” the hornet, the moons of Pluto will cause tidal vibrations. As the various tides meet and interact, both destructively and constructively on occasion, they will cause some heating due to friction and interference when they collide with each other and with various structures in the makeup of Pluto and Charon.  When they collide, or interfere the heat will go off in all directions.

The Differential Rotation will also result in friction and heat throughout the body as we have already stated. When this occurs heat will be released in all directions as well.

However, the heat that is in the direction of the surface of either Charon or Pluto will probably escape to a large degree into the frigid vacuum of space. Neither Charon nor Pluto have an atmosphere capable of significantly containing infrared radiation-although some  of the heat generated by LDR and tidal interference would be trapped by the tenuous atmosphere, but still it would not likely be significant and would have little effect on the geology of the “planets”(or Kuiper Belt Objects if you prefer that terminology.)

However, any heat that is directed towards the core would tend to be trapped in the higher density, and would probably buildup there over time. Just as the Japanese bees direct their vibrations to the center of the mass, where the hornet lies, so too do the tidal vibrations of Pluto’s moons, as does the LDR. Eventually enough heat might well build at the core to explain the geological formations seen on the surface. There does seem to volcanic activity on Pluto, and this could really not easily be explained by any other known process.

This same process used by the Japanese bees must to some degree be active on Earth as well. In the case of Earth, the Moon, Sun and near planets would cause Tidal wave interference and eventually that heat would find a common intersection at the core.  The LDR caused by the Moon’s tidal effects would also accumulate at the core. Of course once this heat began to accumulate significantly other thermo dynamic processes would come into play and the system would become more complex.

Indeed, no matter the process of heating, whether it is due to Layered Differential Rotation, or due to some other cause, the likely buildup of heat would be at the core where any infrared radiation is likely to meet and intersect in the deeper denser layers. This is the simple geometry of the sphere which would concentrate and amplify any radiation emanating from peripheral co-temporal events towards the core.

Heating from any source will accrue towards the center

Therefore heat from any source, even the supposed radioactive decay often proposed as a cause for Earth’s “extra” heat would eventually be concentrated at the core. Though the process of radioactive decay is very unlikely to be the primary cause of core heat in either the Plutonian system, or the Earth Moon system. This decay lasts for too short a time relative to geological time, much less Astronomical time, and is simply not abundant enough to significantly contribute to the geological phenomena we see present in planetary systems. Yet even if radioactive decay were a significant phenomenon, then it would result in the heating of the core as all radiation would intersect there.

Differential Rotation is Probably the Main Cause of Core Heat

Yet the most likely explanation is that the heating we see from all satellite systems seems most likely to be caused by tidal action. For example on Uranus, twin of Neptune -we see little heating. Neptune having a satellite, Uranus lacking one.  Jupiter’s moon Enceladus is a frozen world, yet we see it bursting with core heat.  One might have reason to argue that Venus is quite geologically active with no satellite, yet we can see that Venus has a retrograde revolution which would result in extreme core heating due to the effects of the Sun’s gravitation, should LDR be correct.

The only seeming exception to LDR would be Mercury. Where though we see volcanic activity in the past, we cannot know if it is still geologically active at present. However, Mercury may be exceptional.

It has no atmosphere, and this may help to dissipate heat from the planet’s core.

Also, Mercury by all accounts should have been tidally locked with the Sun, yet it’s not.  Its rotation on its own axis is somewhat faster than its orbital period around the Sun

Was that extra rotation caused by LDR? Were there internal forces within Mercury that prevented it from being tidally locked with the Sun, as would seem most probable?  It’s possible that the high density of Mercury caused a distribution of any excess subsurface rotation to the entire body. The Sun should by all accounts cause some sort of differential rotation within Mercury and this should have resulted in violent geological activity.  Mercury takes approximately 89 days to orbit the Sun, and so and directional acceleration is still quite slow compared to what we might see in the Earth Moon system, or that of Pluto and its satellites.  Still we would expect some differential rotation coming from the Sun and this should result in contemporary seismic activity as well as volcanism.

It is also possible that Mercury is actually quite liquid at the core(as has been recently proposed), but that any volatile gasses have long escaped and thus we cannot see present intense geological activity. But we would still expect violent seismic activity. We’ll go out on the limb and say that there probably is both volcanism on Mercury and substantial seismic activity present even now. However without an atmosphere any such explosions would probably be released into space with little evidence left behind.

Venus, and Earth have an atmosphere and this will react to any volcanism below. Pluto and Charon have ice, and this too will react to any volcanism below-unlike Mercury and the Moon which lack an atmosphere.

Conclusion

In any case, there is not much else that we can see to cause the apparent geological activity in the Plutonian system other that tidal stresses. In the end Ockam’s razor would have to applied and the simplest explanation for the apparent geological activity in the Plutonian system would most probably be a Layered Differential Rotation, as well as the accumulation of heat at the core in a fashion quite similar to the defensive mechanism of a Japanese Bee Hive when faced with a killer predator.  As this heat and stress is released, the surface ice would react accordingly and would explain the landscape.