July 1st, 2017
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I recently posted a question on Reddit under the New Horizons category.
Here's the question along with some dialogue about the theoretical positive gravity anomaly or as I would call it the negative gravity anomaly at Sputnik Planitia. Reddit conversation It's being suggested that Sputnik Planitia (SP) is a positive gravity anomaly (is more dense has more mass) because of a theoretical raised subsurface ocean from a theoretical impact. |
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This positive gravity anomaly, in turn, is supposed to be why SP is aligned directly opposite Charon. Roll an unevenly weighted ball on the floor and it will always come to rest with the heaviest side face the center of earth identical to how our moon is tidally locked with the densest side facing earth. |
Moon gravity map image one
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Moon gravity map image two
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Newton's Law of Universal Gravitation says every mass exerts an attractive force on every other mass, the larger the mass and the closer the objects, the stronger the force. This simple statement explains why the densest part of Pluto must be facing Charon and vise versa.
How is it we have concluded the densest part of Pluto is facing away from the strongest gravitational local pulling force (Charon)?
Doesn't make sense to me.
Can anyone help me understand how Newton's law doesn't apply on Pluto?
synthfish
The densest region of Pluto faces away from the Pluto-Charon system's center of mass due to the system's rotation.
https://en.wikipedia.org/wiki/Barycenter
https://en.wikipedia.org/wiki/Angular_momentum
WikiTextBot
Barycenter
The barycenter (or barycentre; from the Ancient Greek βαρύς heavy + κέντρον centre) is the center of mass of two or more bodies that are orbiting each other, or the point around which they both orbit. It is an important concept in fields such as astronomy and astrophysics. The distance from a body's center of mass to the barycenter can be calculated as a simple two-body problem.
In cases where one of the two objects is considerably more massive than the other (and relatively close), the barycenter will typically be located within the more massive object.
Angular momentum
In physics, angular momentum (rarely, moment of momentum or rotational momentum) is the rotational analog of linear momentum. It is an important quantity in physics because it is a conserved quantity – the angular momentum of a system remains constant unless acted on by an external torque.
The definition of angular momentum for a point particle is a pseudovector r×p, the cross product of the particle's position vector r (relative to some origin) and its momentum vector p = mv. This definition can be applied to each point in continua like solids or fluids, or physical fields.
PlutoPittbull
Why doesn't our moon do the same thing?
I'm no scientist so not sure if I got this right but using the momentum vector formula p = mv (mass X velociy) I get this
Moon Mass 7.342 x 10^22 kg -- Velocity 16.652 kph = 122.259 momentum vector
Pluto Mass 1.303 x 10^22 kg -- Velocity 47.18 kph = 61.476 momentum vector
Seems to me (unless I've got it wrong) Earth's Moon has a larger momentum vector (MV) double that of Pluto and it's densest side faces toward the earth not away from it. With a MV twice that of Pluto and its densest side facing Earth wouldn't this then suggest Pluto should do the same with half the MV of the Moon?
if I understand the momentum vector correctly it is basically the ability of the spin speed acting on the mass to centrifugally whip the denser part of the planet outward or not. If that's correct then our Moon has twice the ability to have its densest side flung away from earth yet its not.
Charon is also about 20 times closer to Pluto than the Moon is to the Earth (12,160 miles vs 230,600 miles) gravity is reduced by the square of the distance so Charon being much closer to Pluto would have a larger gravitational impact (pulling the denser part of Pluto nearer to it) even though its mass is much smaller. I don't know exactly how all these figures work so I'm primarily relying on the Momentum Vector.
Like I said I'm no scientist so if I got it wrong please explain
Thanks
robbak
I think your maps show the reason. While Sputnik Planitia is a positive anomaly, the rest of that side isn't - indeed, it is a strong negative anomaly. Meanwhile, all of the far side is a strongly positive. So, on a planetary, not local, scale, the side nearest Charon is the heaviest.
PlutoPittbull
Those gravity maps are of the Earth's Moon and demonstrate how the densest side of the Moon faces the Earth. New Horizons' didn't have a gravitometer on board so nobody really knows what the gravity displacement on Pluto is like we are simply guessing (speculating) about that.
The Momentum Vector is the most significant info I've yet seen which may help identify what's going on but not sure if I've made a mistake with it or if mine is an accurate interpretation of that info. If what I concluded above is correct then the Moon's doubled MV relative to Pluto's along with the dense side facing the Earth seems to support the idea that the same thing is taking place at the Pluto/Charon system suggesting SP is not a positive gravity anomaly.
SP is 1,300 km (N/S) by 900 km (E/W) and Pluto's diameter is 2378 km. That means SP depending on which direction you measure it is 55% or 38% the diameter of Pluto. It is a pretty large portion of Pluto and if it were a positive gravity anomaly it should in my opinion be facing Charon especially when you throw in the momentum vector (that is unless I've misinterpreted the MV info).
We agree, the densest part of Pluto is facing Charon but if that's the case then seems to me SP is not a positive gravity anomaly rather it is a negative one which when you throw in the fact it is a 2-3 mile deep depression makes sense that it should be a negative gravity anomaly.
How is it we have concluded the densest part of Pluto is facing away from the strongest gravitational local pulling force (Charon)?
Doesn't make sense to me.
Can anyone help me understand how Newton's law doesn't apply on Pluto?
synthfish
The densest region of Pluto faces away from the Pluto-Charon system's center of mass due to the system's rotation.
https://en.wikipedia.org/wiki/Barycenter
https://en.wikipedia.org/wiki/Angular_momentum
WikiTextBot
Barycenter
The barycenter (or barycentre; from the Ancient Greek βαρύς heavy + κέντρον centre) is the center of mass of two or more bodies that are orbiting each other, or the point around which they both orbit. It is an important concept in fields such as astronomy and astrophysics. The distance from a body's center of mass to the barycenter can be calculated as a simple two-body problem.
In cases where one of the two objects is considerably more massive than the other (and relatively close), the barycenter will typically be located within the more massive object.
Angular momentum
In physics, angular momentum (rarely, moment of momentum or rotational momentum) is the rotational analog of linear momentum. It is an important quantity in physics because it is a conserved quantity – the angular momentum of a system remains constant unless acted on by an external torque.
The definition of angular momentum for a point particle is a pseudovector r×p, the cross product of the particle's position vector r (relative to some origin) and its momentum vector p = mv. This definition can be applied to each point in continua like solids or fluids, or physical fields.
PlutoPittbull
Why doesn't our moon do the same thing?
I'm no scientist so not sure if I got this right but using the momentum vector formula p = mv (mass X velociy) I get this
Moon Mass 7.342 x 10^22 kg -- Velocity 16.652 kph = 122.259 momentum vector
Pluto Mass 1.303 x 10^22 kg -- Velocity 47.18 kph = 61.476 momentum vector
Seems to me (unless I've got it wrong) Earth's Moon has a larger momentum vector (MV) double that of Pluto and it's densest side faces toward the earth not away from it. With a MV twice that of Pluto and its densest side facing Earth wouldn't this then suggest Pluto should do the same with half the MV of the Moon?
if I understand the momentum vector correctly it is basically the ability of the spin speed acting on the mass to centrifugally whip the denser part of the planet outward or not. If that's correct then our Moon has twice the ability to have its densest side flung away from earth yet its not.
Charon is also about 20 times closer to Pluto than the Moon is to the Earth (12,160 miles vs 230,600 miles) gravity is reduced by the square of the distance so Charon being much closer to Pluto would have a larger gravitational impact (pulling the denser part of Pluto nearer to it) even though its mass is much smaller. I don't know exactly how all these figures work so I'm primarily relying on the Momentum Vector.
Like I said I'm no scientist so if I got it wrong please explain
Thanks
robbak
I think your maps show the reason. While Sputnik Planitia is a positive anomaly, the rest of that side isn't - indeed, it is a strong negative anomaly. Meanwhile, all of the far side is a strongly positive. So, on a planetary, not local, scale, the side nearest Charon is the heaviest.
PlutoPittbull
Those gravity maps are of the Earth's Moon and demonstrate how the densest side of the Moon faces the Earth. New Horizons' didn't have a gravitometer on board so nobody really knows what the gravity displacement on Pluto is like we are simply guessing (speculating) about that.
The Momentum Vector is the most significant info I've yet seen which may help identify what's going on but not sure if I've made a mistake with it or if mine is an accurate interpretation of that info. If what I concluded above is correct then the Moon's doubled MV relative to Pluto's along with the dense side facing the Earth seems to support the idea that the same thing is taking place at the Pluto/Charon system suggesting SP is not a positive gravity anomaly.
SP is 1,300 km (N/S) by 900 km (E/W) and Pluto's diameter is 2378 km. That means SP depending on which direction you measure it is 55% or 38% the diameter of Pluto. It is a pretty large portion of Pluto and if it were a positive gravity anomaly it should in my opinion be facing Charon especially when you throw in the momentum vector (that is unless I've misinterpreted the MV info).
We agree, the densest part of Pluto is facing Charon but if that's the case then seems to me SP is not a positive gravity anomaly rather it is a negative one which when you throw in the fact it is a 2-3 mile deep depression makes sense that it should be a negative gravity anomaly.
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Francis Nimmo has said that for a core to still be potentially radioactively hot after 4 bya it's radius must be at least 1000 km.
Bill McKinnon says that Pluto's silicate rocky core material is at most 67% of Pluto by mass but only 40% by volume. Pluto's maximum core radius would then be 875 km which is too small to be hot (according to Nimmo). |
Francis Nimmo quote
For a silicate core >1000 km in radius the heat diffusion timescale is longer than the age of the solar system, so large silicate cores provide a long-term reservoir of energy which can potentially maintain a subsurface ocean. Conversely, for bodies with small silicate core radii like Enceladus or Tethys, (I include Pluto's core at 875 km) ancient heat cannot be stored in this manner. |
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But if you throw in the actual information from Robbin Canup's collision model, only about 40% of Pluto heated enough (about 5% at 175 - 250 degrees Kelvin and about 35% at 85 - 150 K) to potentially cause differentiation. Charon remained at 30 K during Canup's impact model. If you then take Bill's 40% volume (rocky material) and take Robin's 40% of that (heated enough to differentiate) times the 1,188 km radius it would suggest Pluto's core is only 350 km (partially differentiated) far too small to be hot and far too small to make a subsurface ocean. Water freezes at 273 K add 5% ammonia and it drops to 176 K. During Canup's collision model theory only about 5% of Pluto could have gotten warm enough to soften water ice to a point allowing for separation and differentiation. Quote from Robin's collision model paper In moon-producing impacts, the satellite material experienced little heating (Temp = 30 K), because it had for the most part avoided direct impact with the planet, whereas the target was heated more substantially (Fig. 2). |
Robin Canup's model figure 2 where 5% is heated to 250 K, 20% to 150 K, 15% to 85 K
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According to F. Nimmo, the original accretion process and small impacts would play a minor to negligible roll in contributing to differentiation. |
Quote from the Francis Nimmo paper
5.2 Heat Production For the icy satellites, there are three main sources of heat: accretion, radioactive decay, and tidal heating. Even for Ganymede-size satellites, the gravitational energy released during accretion is rather modest, so that initial differentiation is not guaranteed [Barr and Canup, 2008]. (Ganymede is more than twice Pluto's size) If accretion happens sufficiently rapidly, some melting will take place [e.g., Lunine and Stevenson, 1982], but the overall contribution to the existence of present-day oceans is minor to negligible. |
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Robbin's model only worked if the two planets that theoretically collided were uniform not differentiated prior to impact.
Differentiated pre-collision planets couldn't work in her model they merged into one ball. For the collision model to work both planets were uniform at collision and weren't heated enough to fully differentiate. Robin Canup's failed pre-differentiated collision model. Fig. 1. Time series of a potential Pluto-Charon–forming impact yielding a planet-disk system (run 70 in table S1 with N 0 120,000 particles). Results are shown looking down onto the plane of the impact at times t - 1.3, 3.2, 7.5, 11.8, 14.5, and 24.6 hours; units shown are distance in 103 km. Color indicates material type (blue, water ice; orange, dunite; red, iron), with all of the particles in the 3D simulation overplotted in order of increasing density. The impacting objects are identical—both are predifferentiated into 40% ice mantles and 60% rock cores by mass with initial surface temperatures set to 150 K, increasing with depth (7) to a central temperature ,800 K. After an initially oblique impact in the counterclockwise sense (A), the two objects separate (B and C) before recolliding. After the second collision, the denser cores migrate toward the center, as a bar-type mode (36) forms in the rapidly rotating merged objects (D). From each end of the bar emanate spiral structures (D and E), whose self-gravity acts to transport angular momentum from inner to outer portions. The arms wrap up on themselves and finally disperse to yield a ring (36) of material (whose differential motion would on a longer time scale produce a disk), together with the central planet (F). |
Robin Canup's collision model with two differentiated bodies colliding then forming into one.
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Without a subsurface bulging ocean (or 40 km deep N2 basin which scientists say is unlikely), SP is a negative gravity anomaly and that's why I say it's facing away from Charon.
Unless I got something wrong?
Unless I got something wrong?
Image credit Francis Nimmo
Figure a) negative gravity anomaly (is a possibility but rather overlooked by scientists) (why?????)
Figure b) SP basin is 40 km deep filled with N2 (also not accepted by scientists because its unreasonably deep).
Figure c) uplifted ocean and SP has a thin crust (accepted by scientists because they WANT an ocean).
Here's a fun fact.
Mars gravity map shows how most of its planitia's are depressions with less gravity (negative gravity anomalies) than surrounding areas.
I'll list them for you.
Figure b) SP basin is 40 km deep filled with N2 (also not accepted by scientists because its unreasonably deep).
Figure c) uplifted ocean and SP has a thin crust (accepted by scientists because they WANT an ocean).
Here's a fun fact.
Mars gravity map shows how most of its planitia's are depressions with less gravity (negative gravity anomalies) than surrounding areas.
I'll list them for you.
- Hellas Planitia - Negative gravity anomaly
- Amazonis Planitia - Negative gravity anomaly
- Arcadia Planitia - Negative gravity anomaly
- Acidalia Planitia - Negative gravity anomaly
- Chryse Planitia - Negative gravity anomaly
- Elysium Planitia - Negative gravity anomaly
- Argyre Planitia - Negative gravity anomaly
That, so far, is the dialogue at Reddit.
The most interesting thing that came out of this discussion for me was the momentum vector formula p = mv (mass X velociy). This is why I like to dialogue with people that disagree with me (have a different view). I get to learn new stuff.
Moon Mass 7.342 x 10^22 kg -- Velocity 16.652 kph = 122.259 momentum vector
Pluto Mass 1.303 x 10^22 kg -- Velocity 47.18 kph = 61.476 momentum vector
These momentum vector figures unless I've misinterpreted them, indicate Pluto has half the spin velocity potential needed for its densest side to be facing away from Charon than our own Moon which has its densest side facing us. If I've interpreted this correctly, Pluto is twice as likely to have its dense side facing Charon as our Moon is to Earth.
This suggests to me we should be using Figure a) in Francis Nimmo's image above since SP is a negative gravity anomaly thereby eliminating false support for the illusionary subsurface water ocean.
The most interesting thing that came out of this discussion for me was the momentum vector formula p = mv (mass X velociy). This is why I like to dialogue with people that disagree with me (have a different view). I get to learn new stuff.
Moon Mass 7.342 x 10^22 kg -- Velocity 16.652 kph = 122.259 momentum vector
Pluto Mass 1.303 x 10^22 kg -- Velocity 47.18 kph = 61.476 momentum vector
These momentum vector figures unless I've misinterpreted them, indicate Pluto has half the spin velocity potential needed for its densest side to be facing away from Charon than our own Moon which has its densest side facing us. If I've interpreted this correctly, Pluto is twice as likely to have its dense side facing Charon as our Moon is to Earth.
This suggests to me we should be using Figure a) in Francis Nimmo's image above since SP is a negative gravity anomaly thereby eliminating false support for the illusionary subsurface water ocean.
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This subsurface ocean of water depends on three things temperature, pressure and ammonia.
Even if Pluto was fully differentiated (unlikely) its core is too small to still be hot making water ice into a liquid. But Nitrogen flows at a much lower temperature 64 K. This temperature can be reached and along with axial wobble nitrogen can reach its triple point turning into a liquid on its surface. Place that nitrogen under ground (increased pressure) and it can relatively easily reach its liquid phase. |
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In order to have a subsurface water ocean you need temperatures greater than 175 K, put that water ice under pressure and less heat energy is required (gonna have to research this more).
NASA scientists have long expected Pluto to deliver certain results. They predetermined Pluto/Charon collided, created a model that only supported partial differentiation but then ignore that fact in errant favor of full differentiation. |
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They ignore their own figures which claim a core radius must be greater than 1,000 km to even potentially still be radioactively hot.
They manipulated impact data on the small satellites to favor their age date preference of 4 bya. At least a year prior to arriving at Pluto scientists were speculating about a subsurface ocean Bill McKinnon was speculating about a Pluto subsurface ocean in 2006. The radiogenic heating provided by the core can potentially melt the mantle ice and form a subsurface ocean (Hussmann et al., 2006; McKinnon, 2006).
They ignore Newton's basic laws of gravity in order to force a subsurface ocean of water (positive gravity anomaly) onto Pluto. They ignore compression ridges (fold mountains) saying only expansion faults exist on Pluto to support a freezing subsurface ocean. False ejecta blankets are created to support a theoretical impact at SP. I've made multiple attempts to point out real cryovolcanoes to Alan Stern, Ashley Davies and others at NASA only to be ignored.
These errors are not born out of educational ignorance as much as unintentional or willful blindness which I guess is a worse form of ignorance. These scientists decided they knew what they would find at Pluto before we got there and their reputations to some degree would be in question if they didn't get it right. Once we arrived, the scene had to fit their preconceptions so they forced it to do so.
On the other hand, I have encountered some impressive and humble scientists along this journey, Jason Cook immediately comes to mind and my friend PolishPlanetPursuer at Zooniverse without whom I'd never have started this site, Alan Stern has also been quite accommodating on twitter. For someone as busy as Alan, I'm impressed he would speak to me on any issue yet he has (he just doesn't seem to want to touch that cryovolcano issue). ChaseAstro has been helpful and there are several others.
There's no conspiracy going on here. This is a matter of simple human nature. Ego, pride, reputation.
They manipulated impact data on the small satellites to favor their age date preference of 4 bya. At least a year prior to arriving at Pluto scientists were speculating about a subsurface ocean Bill McKinnon was speculating about a Pluto subsurface ocean in 2006. The radiogenic heating provided by the core can potentially melt the mantle ice and form a subsurface ocean (Hussmann et al., 2006; McKinnon, 2006).
They ignore Newton's basic laws of gravity in order to force a subsurface ocean of water (positive gravity anomaly) onto Pluto. They ignore compression ridges (fold mountains) saying only expansion faults exist on Pluto to support a freezing subsurface ocean. False ejecta blankets are created to support a theoretical impact at SP. I've made multiple attempts to point out real cryovolcanoes to Alan Stern, Ashley Davies and others at NASA only to be ignored.
These errors are not born out of educational ignorance as much as unintentional or willful blindness which I guess is a worse form of ignorance. These scientists decided they knew what they would find at Pluto before we got there and their reputations to some degree would be in question if they didn't get it right. Once we arrived, the scene had to fit their preconceptions so they forced it to do so.
On the other hand, I have encountered some impressive and humble scientists along this journey, Jason Cook immediately comes to mind and my friend PolishPlanetPursuer at Zooniverse without whom I'd never have started this site, Alan Stern has also been quite accommodating on twitter. For someone as busy as Alan, I'm impressed he would speak to me on any issue yet he has (he just doesn't seem to want to touch that cryovolcano issue). ChaseAstro has been helpful and there are several others.
There's no conspiracy going on here. This is a matter of simple human nature. Ego, pride, reputation.
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I've made plenty of my own interpretive errors on this web site but its been because of educational ignorance. I've tried to point out my mistakes and/or correct them. Its not as though I don't make mistakes too. I've tried to learn and grow my knowledge to reduce my errors because I don't want to mislead anyone.
I suppose this is what separates us, I know so little my eyes are wide open while some scientists' know so much they need not see more. I also don't have a reputation to protect. I have a tremendous amount of respect for what these scientists have accomplished, I just wish they would look, with open minds, at what Pluto/Charon has to say and stop pushing their expectations onto the scene. Just learned something new about volcanism and atmospheres which means something I said previously is not completely correct. Learning can be frustrating as well as exciting but its becoming tedious to have to keep correcting myself. |
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On the one hand, the more I know the better I'm able to build accurate pictures.
On the other hand, it makes me realize how little I know and how potentially wrong my conclusion are.
GRRRRRR!!!!!
Frustrated!
On the other hand, it makes me realize how little I know and how potentially wrong my conclusion are.
GRRRRRR!!!!!
Frustrated!
Update Dec 1st, 2017
The upper portion of the below image released by NASA shows how the higher elevation zone (circle of dots) at Tartarus Dorsa is saturated with higher levels of methane. Methane accumulates at higher elevations.
The lower portion of the image shows concentrations of methane on the opposite side of Sputnik Planitia indicating this zone is elevated higher than most other areas of Pluto. Higher elevations typically equal more mass, meaning the side of Pluto facing Charon is more elevated, more heavy, more dense with a higher degree of gravity, making the none encounter side of Pluto the positive gravity anomaly not the 2-4 mile deep basin called Sputnik Planitia which by way of reason is a negative gravity anomaly.
Upper map is elevation red is highest. Lower map is composition orange is methane. Blurry portion is orange methane heavy suggesting high elevation at these locations.
Typically elevated or thicker land mass equals higher more intense gravity as can be seen in these below images of Earth. Reds are high gravity, blues are low gravity.
For the most part, Mars displays the same thing.
NASA scientist want Pluto to have an ocean of water so bad they ignore basic concepts like this.
Sputnik Planitia is a deep, deep basin while the opposite side is elevated enough to catch and retain atmospheric methane.
The evidence indicates
Sputnik Planitia is a negative gravity anomaly.
Convection currents do not create the mounds on SP
There is no subsurface water ocean.
SP is not an impact site.
The core (if it exists) is cold.
The small satellites are young.
Mordor is an impact site.
Charon and Pluto did not collide.
Wright Mons is not a cryovolcano, I have tried to open their eyes to some real and currently active cryovolcanoes to no avail.
I sent some of this information comparing Earth, Mars and Pluto elevation/gravity maps to Alan Stern in the hopes he would consider its relevance but what I get back is a simple repeat of the party line ideology.
Sputnik Planitia is a deep, deep basin while the opposite side is elevated enough to catch and retain atmospheric methane.
The evidence indicates
Sputnik Planitia is a negative gravity anomaly.
Convection currents do not create the mounds on SP
There is no subsurface water ocean.
SP is not an impact site.
The core (if it exists) is cold.
The small satellites are young.
Mordor is an impact site.
Charon and Pluto did not collide.
Wright Mons is not a cryovolcano, I have tried to open their eyes to some real and currently active cryovolcanoes to no avail.
I sent some of this information comparing Earth, Mars and Pluto elevation/gravity maps to Alan Stern in the hopes he would consider its relevance but what I get back is a simple repeat of the party line ideology.
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Yes, though SP can still be deep. We think the mascon [mass concentration] could be H2O upwelling from the ocean below.
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Nearly everything NASA has suggested about Pluto is wrong.
They did get the Penitentes correct.
I think the many mistakes NASA scientists have made has been for two reasons.
They did get the Penitentes correct.
I think the many mistakes NASA scientists have made has been for two reasons.
- First they decided 10 to 20 years before we arrived at Pluto what we would find, once we arrived it became imperative to force fit the scene into their preconceived notions.
- Second upon our arrival at Pluto the world wanted answers to all these mysteries and the scientists hurriedly interpreted what they saw against the backdrop of what they thought they already new about Pluto. Within days they concluded Wright Mons was a cryovolcano, Sputnik Planitia's smooth mounded surface was created by convection currents and Charon's north pole red stuff was created by cold trapping.
