Began February 28th, 2017
Completed March 17, 2017
Completed March 17, 2017
Update February 8th 2018
Nearly a year after I created this page popular scientific opinion is now beginning to tell a similar story about Triton. I just watched How The Universe Works season 6 episode 5. Several of their statements now match the ones I made on this page. Unfortunately they still think impacts cause planets to tilt on their axis, perhaps they'll eventually read my Tilt page and get that correct too.
Nearly a year after I created this page popular scientific opinion is now beginning to tell a similar story about Triton. I just watched How The Universe Works season 6 episode 5. Several of their statements now match the ones I made on this page. Unfortunately they still think impacts cause planets to tilt on their axis, perhaps they'll eventually read my Tilt page and get that correct too.
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Recently I've been in communication with @ChasAstro on Twitter. He wrote some interesting information on Pluto.
He opened my eyes to something new. We were discussing the possibility of Charon being a Pluto captured object and the difficulties facing the theory of satellite capture. These difficulties are as follows. |
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8 Transneptunian Objects (TNO) aka Transneptunina binaries (TNB)
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He pointed out how “things in solar orbit tend to be moving really fast relative to each other”.
For two objects to get as close as Pluto is to Charon, upon their approach, they tend to either collide as their collective masses will gravitationally drive them toward each other ever faster or they will miss causing them to get flung apart. These same two, commonly accepted, points of view are expressed on Wikipedia. The thing is, however, there are quite a number of Transneptunian Binary (TNB) pairs in and around the Kuiper belt. To the left are eight such objects. |
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In addition to the above 8 binaries, 3/4 down this page is a list of eight newly studied Transneptunian Objects (TNO) which are actually Transneptunian Binaries (TNB).
This gif shows a small moon of asteroid 2004 BL86 passing into view. The moon appears to be orbiting perpendicular to the equator of 2004 BL86. That indicates its a really recently acquired moon as its relatively tiny by comparison and isn't orbiting its parent body's equator. |
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Roughly one third (probably greater than 35%) of observed Kuiper belt objects (icy slow cometary bodies) exist as a binary pair and sixteen percent of main asteroid belt asteroids (rocky speedy Near Earth Objects) exist as a binary pair. This seems to indicate the faster moving asteroids pair up at half the rate of the slower moving TNO's. This makes sense as faster moving objects would tend to impact or miss a close encounter with another fast moving object. Slower objects would tend to enter mutual capture easier as there would be less kinetic energy to overcome.
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<<<<<<<<<< (136617) 1994 CC, a trinary asteroid with two moons. >>>>>>>>> 243 Ida and its moon Dactyl. Yeah that little dot off to the right is a moon. |
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This video of asteroid 2014 JO25 was generated by NASA's Goldstone Solar System Radar on April 18th 2017.
Credits: NASA/JPL-Caltech/GSSR This is a bi-lobe asteroid nearly identical to comet 67p. While capturing satellites may be a difficult process, it isn't that uncommon in the outer solar system. One possible reason binaries occur commonly in the Kuiper belt is because objects are far from the Sun thus moving slower than objects near to the Sun. |
There's also a thing in physics called the 3 body (or N body) problem which indicates a system with more than two bodies tend to eject bodies until we get down to two. They then appear to orbit each other until they merge. Once merged the two are now one oddly shaped object that can then search out a group of bodies ejecting all but one, merge, grow, find more bodies reduce to two, merge and on and on until gravity is strong enough to squish the conjoined odd shaped object into a sphere (hydrostatic equilibrium).
This below asteroid 2014 JO25 passes closer to the Sun than comet 67p and has probably sublimated away most of it's gasses becoming more rock than frozen gasses. Its rotation is 3.5 hours, at perihelion (closest to Sun) its distance = 0.237524 A.U, (1 AU = distance from Earth to Sun) at aphelion (furthest from Sun) its distance = 3.8770 AU. The asteroid belt exists outside Mars' orbit (1.5 AU) between 2 and 3.25 AU. Asteroid 2014 JO25's orbital path takes it closer to the Sun than Mercury, as well as, outside the asteroid belt. 2014 JO25 is a contact binary asteroid, two space rocks that were originally separate bodies, and each segment is about 640 meters and 670 meters, for a total of about 1.3 km long.
This below asteroid 2014 JO25 passes closer to the Sun than comet 67p and has probably sublimated away most of it's gasses becoming more rock than frozen gasses. Its rotation is 3.5 hours, at perihelion (closest to Sun) its distance = 0.237524 A.U, (1 AU = distance from Earth to Sun) at aphelion (furthest from Sun) its distance = 3.8770 AU. The asteroid belt exists outside Mars' orbit (1.5 AU) between 2 and 3.25 AU. Asteroid 2014 JO25's orbital path takes it closer to the Sun than Mercury, as well as, outside the asteroid belt. 2014 JO25 is a contact binary asteroid, two space rocks that were originally separate bodies, and each segment is about 640 meters and 670 meters, for a total of about 1.3 km long.
These are the 30 still images that were used to create the video of Asteroid 2014 JO25
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The New Horizons space craft sped past Pluto and is on its way to visit another Kuiper Belt Object called Ultima Thule (officially named Arrokoth on Nov 12, 2019) and will arrive January first 2019.
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July 17 2017 MU69 (Ultima Thule) passed in front of (occulted) a star which allowed 5 NASA teams to capture multiple images of the shape of New Horizons' next target.
Based on these observations Ultima Thule has to be 20 to 30 km (12 to 18 miles) long and is either bylobed or two separate objects. |
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Update June 1, 2019 As of January 1st 2019, New Horizons flew past comet MU-69 aka Ultima Thule (officially Arrokoth) and found out it is a contact binary. with a very peculiar shape. It appears to be two pancake shaped objects conjoined along their edges. These two objects joined gently. Quote from Massimo
Asteroids suspected of being contact binaries include the unusually elongated 624 Hektor and the bilobated 216 Kleopatra and 4769 Castalia. 25143 Itokawa, which was photographed by the Hayabusa probe, also appears to be a contact binary which has resulted in an elongated, bent body. About 10–15% of near-Earth asteroids larger than 200 meters are expected to be contact binaries with two lobes in mutual contact. |
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Around 35% of icy KBO (comets) and 16% of inner solar system iron rocky objects (asteroids) are either bi-lobed or binary pairs orbiting each other. These numbers indicate similar sized objects regularly interact with each other in a cooperative non destructive manner. The reason probably has to do with conservation of angular momentum. As two similar sized (mass) objects get closer their orbital velocity increases creating centrifugal (outward flinging) force. As they get closer and their orbital spin increases their contact speed decreases. Their increasing orbital spin speed counteracts their gravitational attraction, slowing their contact impact to below their gravitational attraction (escape velocities).
Orbiting objects with dissimilar mass would act quite differently. The smaller object's contact velocity will increase to the gravitational escape velocity of the larger object. The disparity in size would tend to violently suck the small object onto the parent body's surface or fling it out of its gravitational influence.
Orbiting objects with dissimilar mass would act quite differently. The smaller object's contact velocity will increase to the gravitational escape velocity of the larger object. The disparity in size would tend to violently suck the small object onto the parent body's surface or fling it out of its gravitational influence.
Asteroid Schmasteroid - Comet Schmomet what's the diff
- A comet is an icy frozen gas body mixed with silicate rock and/or iron usually found beyond the frost line 3-5 AU from Sun. When comets get closer to the Sun than the frost line, the icy gasses evaporate or sublimate away leaving the silicate rock dust or iron behind converting the comet into an asteroid. Think of the Sun like an oven, the closer an object, the higher the baking temperature and the object's more volatile gasses cook away leaving behind hardened dried material.
- Asteroids are rocky iron material minus the frozen gasses of comets due to them residing sunward of the frost line.
- Meteors are large or small asteroids that pass through our atmosphere and heat to the point of incandescence.
- Meteorites are Meteors that don't get burned up in the atmosphere and actually impact intact onto the Earth's surface. Rock bearing meteorites contain water within the rocky material and tend to explode when heated by entry into our atmosphere so there are far fewer examples of rocky meteorites than iron.
- Micro Meteorites are grains of sand sized meteors that burn up in the atmosphere creating a streak of light (shooting star). Pluto and Triton's atmosphere's are too thin to heat objects as they impact. Earth accumulates 40,000 tonnes of space dust every year, but is loosing more than that in hydrogen. Each year Earth is becoming less gassy and more rocky.
- Meteors come in three flavors on Earth, Iron/nickle, rock (Chondrite) and rock plus iron (Pallasite). Iron meteors, more often than rocky meteors remain in tact as they heat in our atmosphere and collide with Earth while rock and rocky/iron meteor's tend to explode in the air because the friction of hitting our atmosphere heats the moisture inside causing rapid expansion (kaboom).
- On Pluto, impactor's would come in a fourth flavor aka volatiles, frozen gasses such as water ice, methane or nitrogen i.e... comets with far higher concentrations of volatiles than rock material.
- Frozen icy gasses would come in three forms soft, hard and medium.
- Frozen water ice infused with gravel would be hard like rock, tightly compacted water ice and nitrogen would be medium, loosely compacted frozen super volatile gasses like nitrogen, methane and carbon oxides would be soft. Add silicate rock and or iron to a comet and a wide range of mass and density objects could find their way to colliding with Pluto/Triton/Charon.
Comet 67p demonstrates how two bodies can merge gently such that their individual strata is maintained intact and incongruently aligned. Robin Canup's collision model of Pluto/Charon shows how two large bodies could impact gently with little to no heat energy generated on the impacting smaller body.
Several groups of carbonaceous chondrites, contain high percentages (3% to 22%) of water, as well as organic compounds. An organic compound is virtually any chemical compound that contains carbon. Chondrites are stony (non-metallic) meteorites
Basically carbonaceous chondrites are space dust bunnies loaded with carbon. They are the most common type of meteorite that falls to Earth varying between 85.7% and 86.2%.
Meteorites - Iron, Chondrite (stone), Pallasite (mixed stone/iron) and
Soft, Med, Hard Dirty Snow Balls.
In ancient times before the iron age, iron meteorites fell from the sky heated in the atmosphere and formed malleable metals. They were then shaped into objects such as a rare hammer or sword from the gods. This blade was King Tut's and was forged from a meteorite (pre iron age).
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This video is how most people tend to view collisions between bodies in space and while it is inevitable many collisions take place in a manner similar to this (due to speed and mass mismatch), I, however, see another form of collision that takes place and is much less disruptive or cataclysmic.
The relatively large number of similarly sized conjoined objects seem to indicate that while binaries of dissimilar size join in a way that would appear violent since the small object obliterates on impact to be absorbed by the larger body, bodies of similar size, however, enter into a tug of war orbital dance, each offsetting the gravitational pull of the other until they gently merge into one odd shape. |
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Conservation of momentum suggests that as the two bodies come closer their orbital spin speed increases creating increased centrifugal force which in turn is trying to fling them apart.
The closer they get the faster they spin, the faster they spin, the slower they impact. If Pluto and Charon's orbital spin speed around their collective barycenter is increasing over time they are coming closer together. Conversely, if their barycentric orbital rotation is decreasing they're separating. Everything I've read so far seems to indicate their orbital speeds are stable but I doubt anyone yet knows for sure. |
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Conjoined bodies
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Just as comet 67p and Neptune's largest moon Triton are/were Kuiper Belt Object's (KBO) so too are Pluto and Charon. Comet 67p was a binary pair until two distinctly different objects gently merged and married into one. Their collision was so gentle in fact they maintained their individually aligned strata while merging into one body.
Over time, dust and other particles began filling in the connecting neck. Then something kicked comet 67p into an extreme short period orbit around the Sun causing it to become a comet as it then sublimated away ices by the heat of the Sun. |
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Comet 67p a bylobed conjoined pair that, at one time, orbited each other
As it nears the Sun, it heats up and ejects dust and debris eroding away the material at the neck causing the connection between these two bodies to become ever more tenuous. Eight inches of dust has accumulated on the surface of 67p from sublimation (evaporating ices directly into gasses) ejecting dust particles while leaving some behind which built up this dust layer.
Comet 67p dual strata
The neck looks as though it has twisted under the stress of holding these two bodies together.
Comet 67p neck
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Some images like this one are here simply because of their magnificence Absolutely blown away by this image of comet 67p |
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To give a sense of scale comet 67p is about 1/3 the size of Styx which is the smallest of Pluto's moons.
Comet 67p has a reflectance or albedo of .06 (6%) and is really dark because of all the regolith on its surface. It is covered in 8 inches of dark dust or regolith. Regular charcoal used in a barbecue grill has an albedo of .04 (4%) so Comet 67P is just slightly brighter than charcoal, however, you couldn't tell the difference with your eyes.
Quote from Universe Today Article
Astronomers rank an object’s reflectivity by its albedo (al-BEE-do). A body that reflects 100% of the light is said to have an albedo of 1.0. Venus’ albedo is .75 and reflects 75% of the light it receives from the sun, while the darker Earth’s average is 30%. Trees and the darker-toned continents reflect much less light compared to Venus’ pervasive cloud cover. In contrast, the coal-dark moon reflects only 12% of the sunlight falling on it and fresh asphalt just 4% – smack in the middle of the 2-6% range of most known comets.
The below image shows a comparison of how dark comet 67p is relative to Enceladus, Earth and our Moon
Quote from Universe Today Article
Astronomers rank an object’s reflectivity by its albedo (al-BEE-do). A body that reflects 100% of the light is said to have an albedo of 1.0. Venus’ albedo is .75 and reflects 75% of the light it receives from the sun, while the darker Earth’s average is 30%. Trees and the darker-toned continents reflect much less light compared to Venus’ pervasive cloud cover. In contrast, the coal-dark moon reflects only 12% of the sunlight falling on it and fresh asphalt just 4% – smack in the middle of the 2-6% range of most known comets.
The below image shows a comparison of how dark comet 67p is relative to Enceladus, Earth and our Moon
This image gives a sense of scale for Pluto's size compared to other bodies. Notice the relative size proximity of Pluto to Triton.
Back to the theme of Transneptunian binaries TNB.
The thing is, it is commonly accepted that captured satellites are rare because they should either collide and self destruct or catapult each other apart but there is plenty of evidence suggesting Transneptunian Objects TNO or Kuiper Belt Object KBO which exist as captured satellites are not all that rare.
@ChasAstro referenced Triton, a captured moon of Neptune, as an example of a KBO that apparently defied this general rule. This got me interested in studying Triton more closely in an effort to understand how satellite capture might occur.
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Triton is the second outermost moon of Neptune and it has some peculiar features which suggest strongly that it is a captured KBO, whereas, Neptune's smaller inner moons are reasoned to be accreted from debris. @ChasAstro "Nereid is actually the outermost satellite of Neptune. Some people have hypothesized that Nereid might have originally been a regular satellite in a circular orbit but was displaced to its present wide irregular orbit during Triton’s capture."
Neptune orbits around 30 AU from the sun. One Astronomical Unit (AU) is the distance of the Earth to the Sun so Neptune is 30 times further away from the Sun as the Earth. KBO's reside in a relatively circular doughnut ring orbiting approximately 40-50AU from the Sun at an inclination of less than 5 degrees relative to the ecliptic plane (orbital plane of Earth to Sun). So why is Triton thought to be a captured KBO when it should normally exist 15 AU further away from the Sun than Neptune? And how did it drop 15 AU closer to the Sun to become captured by Neptune? 
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Triton with dark streaks of geyser gas plumes released from cryovolcanic activity
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This is the orbit of Nereid compared to that little tiny orbital blue circle which is Triton going around Neptune. Wiki says Nereid orbits Neptune in the prograde direction at an average distance of 5,513,400 km (3,425,900 mi), but its high eccentricity of 0.7507 takes it as close as 1,372,000 km (853,000 mi) and as far as 9,655,000 km (5,999,000 mi). The gravitational influence of a body is reduced by the square of its distance. Doubling the distance means quadrupling the weakness of the gravitational torque force. |
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This short video demonstrates how moons that orbit near a parent planet like Jupiter (in this example) remain closely aligned around the planet's equatorial plane.
Jupiter's axis is only tilted 3 degrees off its orbital plane but its nearest moons align with its 3 degree tilted rotation. Saturn is tilted 27 degrees and its rings and inner moons mostly all align with its equator while further out moons are more random in their orbital paths. Orbiting bodies further out tend to orbit in more random spherical patterns. |
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When Nereid reaches periapsis (closest to Neptune) in its orbit, it is also closest to Triton and speeds up. Each orbit near periapsis the potential exists for Nereid to receive a resonant push from Triton both elongating and creating its inclined orbital angle relative to Neptune's equator. Neptune's other moons are puny, close to and inline with its equator. Triton is 99.5% of the entire mass orbiting Neptune so its not too difficult to believe it has perturbed Nereid into its current orbit.. |
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The orbit of Triton (red) is opposite in direction and tilted −23° compared to a typical moon's orbit (green) in the plane of Neptune's equator.
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Relative to Neptune Triton orbits in a retrograde or backward spin while it's other moons orbit in a prograde direction in line with Neptune's equator.
Triton is compositionally very similar to Pluto which is also a KBO that is in a 2:3 resonance with Neptune. Pluto orbits the Sun 2 times while Neptune orbits 3 times hence 2:3 resonance. Triton is very geologically active, the majority of it's surface is mostly smooth or recently resurfaced by roiling activity or cryovolcanism and its shell is too thin to support large elevated structures (mountains). |
Triton's orbit and distance from Neptune relative to the other moons (closer to scale).
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Like Pluto, Triton has a very thin atmosphere. Triton is primarily made of the same stuff as other KBO mostly nitrogen, methane, carbon monoxide, water ice and rocky material. Triton's density is 2.06 g/cm3 while Pluto's is 1.86 g/cm3. A moon composed strictly of water ice would be 1 g/cm3. A density greater than one indicates heavier materials like silicate rock (rock density = 2.5-3.5 g/cm3) are present. Like Pluto, Triton is composed of heavier materials than water ice meaning Triton's silicate rock mass is about 66% (Pluto = 67%) 36-40% by volume. Triton's massive cantaloupe looking thin skin and cryovolcanic activity depositing dark minerals on the surface suggest it's core is fully differentiated and there is a warm ocean keeping the outer shell soft enough to lack impact craters and elevated structures. |
Triton's thin atmosphere
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Triton's orbit relative to Neptune (not to scale)
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Triton is locked to Neptune so one side always faces Neptune and the eccentricity of its orbit is a near perfect circle at .000016 yet Triton is geologically extremely active for the following reason. Triton's orbit is angled -23 degrees relative to Neptune's equator. Triton is 99.5 % of all the mass orbiting Neptune. Neptune has 14 moons and only Triton is in hydrostatic equilibrium (big enough to make itself round). |
Wikipedia says
Gravitational capture of an object is not easy: it requires some mechanism to slow down the object enough to be caught by the larger object's gravity. A possible explanation is that Triton was part of a binary when it encountered Neptune (Pluto/Triton Binary?). (Many KBOs are members of binaries. (seems to be contradictory statements "gravitational capture is difficult yet many KBOs are binaries")) Ejection of the other member of the binary by Neptune could then explain Triton's capture.
NASA says
Tidal forces from its (Triton's) lopsided orbit are powerful enough to keep the interior active.
Quote from "Ask an Astronomer"
A moon on an inclined (tilted) orbit, passing above and below the equator of the planet, will have its tidal bulge constantly moving up and down. The movement of the bulge leads to friction and heat. That friction acts to try to stop the moon from going up and down, that is, decrease its inclination, or make it orbit around the equator of the planet.
In a nutshell Triton is orbiting Neptune at an inclined orbit to it's equator which is causing tidal stretch energy on Triton as it oscillates above and below Neptune's equator. Even though Triton is in a near perfect circular orbit to it's parent body (no in/out tidal flex energy) it acquires heat energy from its off angle orbit relative to Neptune's equator. Funny how nobody assumes Triton has a radioactively hot core but Pluto supposedly does, Triton's energy is assumed to come from tidal flex while in a perfect circular orbit. Pluto's density and size are smaller than Triton yet Triton's geological activity is reasoned to be from a wandering tidal bulge energy not from a radioactively hot core.
Triton's axis wobbles relative to Neptune 127 to 180 (53) degrees. While this wobble takes place, gravitational torque would be induced from one onto the other. Pluto and Charon's axial poles likewise wobble (page 78) from 102 to 126 (24) degrees in 1.4 Myr. This wobble was probably more energetic in Pluto's past and contributed to the wandering tidal bulge flex energy induced into each which contributed to their fluid like surface features. The extreme wobble suggests youth. Both Pluto and Triton are in a state of extreme slow wobble unlike how the young small satellites Styx, Nix, Kerberos & Hydra orbiting Pluto are in a state of extreme fast wobble. Despinning along with initial early extreme eccentric orbits would have generated a great deal of tidal flex energy. If their initial eccentric orbits creating tidal flex process took place within the last billion years, the residual heat would still be present especially when combined with their current axial wobble.
Gravitational capture of an object is not easy: it requires some mechanism to slow down the object enough to be caught by the larger object's gravity. A possible explanation is that Triton was part of a binary when it encountered Neptune (Pluto/Triton Binary?). (Many KBOs are members of binaries. (seems to be contradictory statements "gravitational capture is difficult yet many KBOs are binaries")) Ejection of the other member of the binary by Neptune could then explain Triton's capture.
NASA says
Tidal forces from its (Triton's) lopsided orbit are powerful enough to keep the interior active.
Quote from "Ask an Astronomer"
A moon on an inclined (tilted) orbit, passing above and below the equator of the planet, will have its tidal bulge constantly moving up and down. The movement of the bulge leads to friction and heat. That friction acts to try to stop the moon from going up and down, that is, decrease its inclination, or make it orbit around the equator of the planet.
In a nutshell Triton is orbiting Neptune at an inclined orbit to it's equator which is causing tidal stretch energy on Triton as it oscillates above and below Neptune's equator. Even though Triton is in a near perfect circular orbit to it's parent body (no in/out tidal flex energy) it acquires heat energy from its off angle orbit relative to Neptune's equator. Funny how nobody assumes Triton has a radioactively hot core but Pluto supposedly does, Triton's energy is assumed to come from tidal flex while in a perfect circular orbit. Pluto's density and size are smaller than Triton yet Triton's geological activity is reasoned to be from a wandering tidal bulge energy not from a radioactively hot core.
Triton's axis wobbles relative to Neptune 127 to 180 (53) degrees. While this wobble takes place, gravitational torque would be induced from one onto the other. Pluto and Charon's axial poles likewise wobble (page 78) from 102 to 126 (24) degrees in 1.4 Myr. This wobble was probably more energetic in Pluto's past and contributed to the wandering tidal bulge flex energy induced into each which contributed to their fluid like surface features. The extreme wobble suggests youth. Both Pluto and Triton are in a state of extreme slow wobble unlike how the young small satellites Styx, Nix, Kerberos & Hydra orbiting Pluto are in a state of extreme fast wobble. Despinning along with initial early extreme eccentric orbits would have generated a great deal of tidal flex energy. If their initial eccentric orbits creating tidal flex process took place within the last billion years, the residual heat would still be present especially when combined with their current axial wobble.
Comparison of the orbits of scattered disc objects (black), classical KBOs (blue), and 2:5 resonant objects (green). Orbits of other KBOs are gray. (Orbital axes have been aligned for comparison.)
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Wiki quote
The presence of Neptune has a profound effect on the Kuiper belt's structure due to orbital resonances... Neptune's gravity destabilizes the orbits of any objects that happen to lie in certain regions. Cold KBOs reside primarily around 42 – 50 AU maintaining a fairly circular orbit (blue Classical ring in image) around the Sun with low inclinations <5° to the ecliptic plane. Classical Kuiper Belt Objects (KBO), also known as Cold KBOs or Cubewanos are typically more red (tholin covered) than Hot inclined Transneptunian Objects (TNO) (not named for temperatures rather orbital inclinations of greater than 5 degrees). TNO's and KBO's may overlap but typically KBO's sit in the quiet doughnut shaped blue ring while TNO's are often objects scattered by Neptune into resonance, extreme inclinations and/or extreme eccentric orbits. Hot TNOs are more varied in their color ranges from grays to reds with inclinations from 5 to 40 degrees and eccentricities up to .85 which is massive. |
The color and albedo (reflectance) indicate Pluto was most likely a cold KBO but it is currently in an eccentric (0.2488) and 17° inclined orbit to the Sun clearly defining it currently as a Hot TNO but is often referred to as a KBO because its in the same orbital range as other KBO's.
The question for Pluto then is how did a once red cold KBO become a hot TNO? Cold KBO are red, dormant, stable and unperturbed objects. The grand tack or Nice model suggest Neptune migrated from near the Sun (10-15 AU) to its current orbit at 30 AU. Pluto has also, in response to Neptune's migration been perturbed from it's original circular Classical cold < 5 degree inclination zone to it's current 2:3 resonant, 17 degree inclined 0.2488 eccentric orbital hot zone. Charon, on the other hand, is gray and compositionally different than Pluto suggesting it never was a classical KBO.
The question for Pluto then is how did a once red cold KBO become a hot TNO? Cold KBO are red, dormant, stable and unperturbed objects. The grand tack or Nice model suggest Neptune migrated from near the Sun (10-15 AU) to its current orbit at 30 AU. Pluto has also, in response to Neptune's migration been perturbed from it's original circular Classical cold < 5 degree inclination zone to it's current 2:3 resonant, 17 degree inclined 0.2488 eccentric orbital hot zone. Charon, on the other hand, is gray and compositionally different than Pluto suggesting it never was a classical KBO.
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Known objects in the Kuiper belt beyond the orbit of Neptune. (Scale in AU; epoch as of January 2015.)
Sun - Yel Jupiter trojans - Gray Giant planets: J · S · U · N - Red dots Centaurs - Green dots Kuiper belt - Blue Scattered disc - Beige Neptune trojans - Purple Distances but not sizes are to scale Source: Minor Planet Center, www.cfeps.net and others 
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The difference in color and albedo suggest these two types of objects Cold vs Hot KBOs were formed in different zones of the solar system making them compositionally different or due to Neptune"s perturbation effect they currently exhibit a mixed bag of objects. It is thought Cold KBO's formed pretty much out in the 42-50 AU zone while Hot KBOs formed closer to Jupiter but were subsequently perturbed into more radical scattered orbits during the planetary migration process suggested in the Nice model. These scattered Neptune objects display signs of activity otherwise unseen in classical KBO.
Moons orbiting the gas giants Saturn and Jupiter are grayish while the cold classical KBO are redish suggesting their colors tend to relate to these two zones 5-10 AU (gray) vs 40-50 AU (red). Hot KBO with increased orbital inclinations to the ecliptic plane, extended eccentricities and mixed colors suggest these objects are from both zones and were perturbed by Neptune into oddball orbits creating what is often called scattered disk objects as they have been scattered by Neptune.
Thirty five percent of cold classical KBO exist in binary pairs while about 5 percent of scattered disk objects exist in binary pairs. As Neptune migrated outward, it stirred the pot and mixed some of the inner gray objects with the outer cold red objects and activated some churning within the red perturbed objects creating the mix of hot objects. This scattering effect is most likely the reason why larger quantities of binaries exist in the old quiet neighborhood of the cold classical zone.
Pluto's moon Charon exhibits traits of a Hot KBO, Hot KBOs have inclined orbits from 5 to 40°. Cold classical KBO with low inclinations have a color pattern of red which is what Pluto exhibits. This is strong suggestive evidence Pluto and Charon were mixed together by Neptune. The evidence also suggests Pluto and Triton belong together, however, Pluto and Charon don't, unless you consider a previous interaction took place between these three bodies.
Moons orbiting the gas giants Saturn and Jupiter are grayish while the cold classical KBO are redish suggesting their colors tend to relate to these two zones 5-10 AU (gray) vs 40-50 AU (red). Hot KBO with increased orbital inclinations to the ecliptic plane, extended eccentricities and mixed colors suggest these objects are from both zones and were perturbed by Neptune into oddball orbits creating what is often called scattered disk objects as they have been scattered by Neptune.
Thirty five percent of cold classical KBO exist in binary pairs while about 5 percent of scattered disk objects exist in binary pairs. As Neptune migrated outward, it stirred the pot and mixed some of the inner gray objects with the outer cold red objects and activated some churning within the red perturbed objects creating the mix of hot objects. This scattering effect is most likely the reason why larger quantities of binaries exist in the old quiet neighborhood of the cold classical zone.
Pluto's moon Charon exhibits traits of a Hot KBO, Hot KBOs have inclined orbits from 5 to 40°. Cold classical KBO with low inclinations have a color pattern of red which is what Pluto exhibits. This is strong suggestive evidence Pluto and Charon were mixed together by Neptune. The evidence also suggests Pluto and Triton belong together, however, Pluto and Charon don't, unless you consider a previous interaction took place between these three bodies.
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I've been reading some of Francis Nimmo's paper's this one in particular. Five New and Three Improved Mutual Orbits of Transneptunian Binaries In this paper, Kuiper Belt Object's which exist as binary pairs orbiting around a shared barycentric point are studied. Quote - "most of these systems consist of near equal-sized pairs" Triton is shown below in false color while Pluto is displayed in natural color in reality Triton's color looks nearly identical to Pluto. Triton's natural color is shown in this image to the right. >>> The image below is only for size comparison. Triton's radius = 1.353 km, Pluto's radius = 1,188 km. |
Triton in natural color
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Triton is in false color Pluto is in natural color. Triton and Pluto look nearly identical in natural color.
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Triton natural color
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Charon, Pluto and Triton shown in natural color (sorta) for color comparison. Charon and Pluto are to scale relative to each other, Triton is not to scale by size. Pluto and Triton are a size and color match, Charon is the odd ball.
Below are download links to the closest natural color highest resolution image NASA has produced of Pluto and Charon
Below are download links to the closest natural color highest resolution image NASA has produced of Pluto and Charon
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Pluto in true natural color
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The more we explore space the more we find binary pairs of near equal size, mass and composition either attached or orbiting each other. Below quote is from an article issued by the space telescope science institute in Baltimore, Maryland dated Sept 21st, 2017 Quote Hubble was used to image the asteroid, designated 300163 (2006 VW139/288P), in September 2016 just before the asteroid made its closest approach to the Sun. Hubble’s crisp images revealed that it was actually not one, but two asteroids of almost the same mass and size, orbiting each other at a distance of 60 miles. Transneptunian Binaries (TNB) are binary pairs mostly loosely bound as they orbit each other and most of them are similar in size mass and composition just like Pluto and Triton. Below is an image of the TNB object's studied in F. Nimmo's paper with their shared orbits. Logos and Zoe are the first TNB in this chart. |
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Below image is the orbital paths of Neptune/Triton (Purple), Pluto/Charon (Orange), Logos/Zoe (Gray). Logos/Zoe is a TNB orbiting around the Sun (Yellow) . The Logos/Zoe binary pair is considered a TNO or TNB or some might even suggest them to be KBO's. Note how they fall within Pluto/Charon's orbital path and have been migrated into this position by Neptune suggesting similar processes may have also taken place with a Pluto Triton binary which were forced by Neptune to encounter Charon.
Neptune/Triton (Purple), Pluto/Charon (Orange), Logos/Zoe (Gray) Sun (Yellow)
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Logos and Zoe are TNB that perform a dance something like this.
Logos & Zoe simulation
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From this information I choose to speculate on a possible interaction scenario between Pluto, Triton, Charon & Neptune. What if? Pluto and Triton were a binary pair of cold classical KBO with their similar sizes, compositions, densities and colors minding their own business in the Kuiper Belt then Neptune migrated close enough and regular enough (resonance) to gently perturbed them out of their classical Kuiper belt comfort zone causing them to slowly experience an increasingly eccentric orbit. Each pass Neptune made near to them it's gravitational mass increased Pluto/Triton's angle of inclination and eccentricity pushing them into an orbital zone we call a Neptune 3:2 resonance along with other similarly clustered 3:2 resonant objects including Charon. |
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I'm suggesting Charon was already in a 3:2 resonance with Neptune as Neptune migrated outward and into the Kuiper Belt then Pluto/Triton were likewise perturbed into this 3:2 resonant zone. Had we been able to see objects in this 3:2 resonant Pluto zone one or two billion years ago we would have seen Charon all by itself and would have named this zone the Charino zone because at that time Charon would have been the largest object in that zone.
October 13th, 2017 Just learned about an effect called the Kozai mechanism which is a perturbation of the orbit of a satellite by the gravity of another body orbiting farther out, causing libration (oscillation about a constant value) of the orbit's argument of pericenter. As the orbit librates, there is a periodic exchange between its inclination and its eccentricity.
October 13th, 2017 Just learned about an effect called the Kozai mechanism which is a perturbation of the orbit of a satellite by the gravity of another body orbiting farther out, causing libration (oscillation about a constant value) of the orbit's argument of pericenter. As the orbit librates, there is a periodic exchange between its inclination and its eccentricity.
image by Randy Russell
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As Neptune gravitationally pushed or pulsed Pluto/Triton it changed their orbital eccentricity along with their orbital inclination (Kozai mechanism). Pluto and Charon are currently in an eccentric orbit around the Sun that places them periodically closer to the Sun than Neptune.
The orbit of Pluto is the most eccentric of any planet in our Solar System. Pluto's orbital eccentricity is 0.2488. Back in the day when the binary pair Pluto/Triton got close enough to Charon in the 3:2 resonant zone, the three set up an unbalanced system that caused Triton to exit the trio. |
Have you ever heard the phrase, "Two's company, three's a crowd"? Well this holds true for closely orbiting bodies in space.
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In physics there's this thing called the Three-body problem or N-body problem (N = any number of bodies greater than 1) which, in a nut shell, indicates 3 bodies or more will tend to eject bodies until there are typically only two bodies in a close knit system.
This gif represents one potentially real orbital solution to the 3 body problem but it requires that all three bodies be of equal mass to remain stable (extremely unlikely). |
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If Neptune perturbed one of its 3:2 resonant bodies called Charon within the gravitational influence of a TNB two body system called Pluto/Triton (creating a three body system) then one of three had to go.
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If the ejection occurred while they were closer to the Sun than Neptune it would have placed Triton into Neptune's orbital path. Charon latched onto Pluto while Triton fell into Neptune's grasp. This jostling created tidal flex on all three planets.
Something like this >>>>>>>>>> Which eventually turned into Pluto/Charon doing this 
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Triton was eventually captured in a counter rotating orbit as Neptune passed near by.
Pluto travels faster at perihelion (nearest the Sun) than at aphelion (farthest from Sun) so depending on where Triton exited the trio (Pluto, Charon, Triton) would determine whether Triton needed to leave faster or slower to get dropped into Neptune's path. |
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The conditions could have been such that Triton got pushed into Neptune's orbit.
Since Pluto crosses inside and outside Neptune's orbital range, it crosses Neptune's orbital distance twice each orbit around the Sun. If Triton ejected near either of these two locations, Neptune could have latched onto and picked it up. Think of it like a gravity assist which we use with space probes to gain velocity. If Triton ejected from the trio at perihelion it would have been traveling faster than Neptune and could have caught up with it or if Triton ejected at an orbit further from the Sun it would have been moving slower than Neptune and slowed into it's orbital and gravitational range. |
Pluto's crossing orbit with Neptune
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While this thought is total speculation it seems interesting to me that Pluto and Triton are so similar in mass, size, density, composition, axial wobble and geological activity. Triton's backward spin, angle relative to Neptune's equator and compositional difference strongly suggest it is a captured KBO. All Neptune's other moons are tiny and compositionally similar and orbiting mostly in the same direction but not Triton. Within the Neptune system, Triton stands out like a sore thumb, it is the odd man out.
Triton's similarity to Pluto suggests it may have once, not so long ago, shared an orbit with Pluto then Charon came along and upset the apple cart. TransNeptunian Binaries are common and are frequently similar in size. Triton (radius = 1,353 km) is only slightly larger than Pluto (radius = 1,188 km). Their densities are similar (Triton = 2.061 g/cm3, Pluto = 1.854 g/cm3), both of their orbital axial wobbles are extreme, their geological activities are similar (cryovolcanoes large swaths of young resurfaced crust) Triton does display more geologic activity (heat), they are compositionally similar (N2, nitrogen, CH4, methane) suggesting to me they were probably once part of the same TNB pair.
How do their geological ages align?
Quote from "Ask an Astronomer"
A moon on an inclined (tilted) orbit, passing above and below the equator of the planet, will have its tidal bulge constantly moving up and down. The movement of the bulge leads to friction and heat. That friction acts to try to stop the moon from going up and down, that is, decrease its inclination, or make it orbit around the equator of the planet.
It takes less than a billion years for tidal friction to make the orbit of most moons equatorial. If a moon is in an inclined orbit, then astronomers have a puzzle to solve.
Triton's orbital angle relative to Neptune's equator indicate it has been captured within the last 1 billion years. Pluto's Sputnik Planitia being so active, suggests it is also the result of recent processes perhaps on the order of 700 Myr. If Triton and Pluto were once a binary pair which I suspect they were then Triton's orbital inclination relative to Neptune is a rough date indicator for when Triton and Pluto separated which is also a rough date indicator of when Pluto and Charon began their mutual initial eccentric orbital dance.
I'm guessing the separation of Triton from Pluto/Charon took place about 700 mya to 1.5 byr. This is when Pluto and Charon began their tidal flex dance. Pluto and Charon being more closely matched in size and orbital distance to each other aligned poles and equatorial orbits more readily than Triton did with Neptune.
Ammonia Hydrates, according to various scientists puts some surface material on Pluto's small moon's at less than 20 to 200 myr. Then there's Charon's southern hemisphere that was heated to >90K within the last 100,000 years indicated by crystalline water ice which becomes amorphous within 100,000 years at temperatures below 78 degrees K. Pluto's small moons orbit's while circular are erratic and their albedo's are far too bright for them to be old. All this info indicates these processes are much more recent than mainstream media scientists suggest.
Triton's similarity to Pluto suggests it may have once, not so long ago, shared an orbit with Pluto then Charon came along and upset the apple cart. TransNeptunian Binaries are common and are frequently similar in size. Triton (radius = 1,353 km) is only slightly larger than Pluto (radius = 1,188 km). Their densities are similar (Triton = 2.061 g/cm3, Pluto = 1.854 g/cm3), both of their orbital axial wobbles are extreme, their geological activities are similar (cryovolcanoes large swaths of young resurfaced crust) Triton does display more geologic activity (heat), they are compositionally similar (N2, nitrogen, CH4, methane) suggesting to me they were probably once part of the same TNB pair.
How do their geological ages align?
Quote from "Ask an Astronomer"
A moon on an inclined (tilted) orbit, passing above and below the equator of the planet, will have its tidal bulge constantly moving up and down. The movement of the bulge leads to friction and heat. That friction acts to try to stop the moon from going up and down, that is, decrease its inclination, or make it orbit around the equator of the planet.
It takes less than a billion years for tidal friction to make the orbit of most moons equatorial. If a moon is in an inclined orbit, then astronomers have a puzzle to solve.
Triton's orbital angle relative to Neptune's equator indicate it has been captured within the last 1 billion years. Pluto's Sputnik Planitia being so active, suggests it is also the result of recent processes perhaps on the order of 700 Myr. If Triton and Pluto were once a binary pair which I suspect they were then Triton's orbital inclination relative to Neptune is a rough date indicator for when Triton and Pluto separated which is also a rough date indicator of when Pluto and Charon began their mutual initial eccentric orbital dance.
I'm guessing the separation of Triton from Pluto/Charon took place about 700 mya to 1.5 byr. This is when Pluto and Charon began their tidal flex dance. Pluto and Charon being more closely matched in size and orbital distance to each other aligned poles and equatorial orbits more readily than Triton did with Neptune.
Ammonia Hydrates, according to various scientists puts some surface material on Pluto's small moon's at less than 20 to 200 myr. Then there's Charon's southern hemisphere that was heated to >90K within the last 100,000 years indicated by crystalline water ice which becomes amorphous within 100,000 years at temperatures below 78 degrees K. Pluto's small moons orbit's while circular are erratic and their albedo's are far too bright for them to be old. All this info indicates these processes are much more recent than mainstream media scientists suggest.
Update, April 20th 2018 (One year & two months after creating this page)
I just came across a paper called 2007 TY430: A Cold Classical Kuiper Belt Type Binary in the Plutino Population
Quote
Kuiper Belt object 2007 TY430 is the first wide, equal-sized, binary known in the 3:2 mean motion resonance with Neptune. (Pluto is in a 3:2 resonance with Neptune and is equal-sized to Triton). The two components have a maximum separation of about 1 arcsecond and are on average less than 0.1 magnitudes different in apparent magnitude with identical ultra-red colors (g − i = 1.49 ± 0.01 mags). (Both Pluto and Triton are red with tholin just like the 2007 TY430 binary).
Using nearly monthly observations of 2007 TY430 from 2007-2011, the orbit of the mutual components was found to have a period of 961.2 ± 4.6 days with a semi-major axis of 21000 ± 160 km and eccentricity of 0.1529±0.0028. The inclination with respect to the ecliptic is 15.68±0.22 degrees (Pluto/Charon = 17) and extensive observations have allowed the mirror orbit to be eliminated as a possibility.
The total mass for the binary system was found to be 7.90 ± 0.21 × 10^17 kg. Equal-sized, wide binaries and ultra-red colors are common in the low inclination “cold” classical part of the Kuiper Belt and likely formed through some sort of three body interactions within a much denser Kuiper Belt. (The same scenario I described a year ago (on this page) which could have taken place with Triton/Pluto/Charon).
To date 2007 TY430 is the only ultra-red, equal-sized binary known outside of the classical Kuiper belt population. Numerical simulations suggest 2007 TY430 is moderately unstable in the outer part of the 3:2 resonance and thus 2007 TY430 is likely an escaped “cold” classical object that later got trapped in the 3:2 resonance.
Quote
Kuiper Belt object 2007 TY430 is the first wide, equal-sized, binary known in the 3:2 mean motion resonance with Neptune. (Pluto is in a 3:2 resonance with Neptune and is equal-sized to Triton). The two components have a maximum separation of about 1 arcsecond and are on average less than 0.1 magnitudes different in apparent magnitude with identical ultra-red colors (g − i = 1.49 ± 0.01 mags). (Both Pluto and Triton are red with tholin just like the 2007 TY430 binary).
Using nearly monthly observations of 2007 TY430 from 2007-2011, the orbit of the mutual components was found to have a period of 961.2 ± 4.6 days with a semi-major axis of 21000 ± 160 km and eccentricity of 0.1529±0.0028. The inclination with respect to the ecliptic is 15.68±0.22 degrees (Pluto/Charon = 17) and extensive observations have allowed the mirror orbit to be eliminated as a possibility.
The total mass for the binary system was found to be 7.90 ± 0.21 × 10^17 kg. Equal-sized, wide binaries and ultra-red colors are common in the low inclination “cold” classical part of the Kuiper Belt and likely formed through some sort of three body interactions within a much denser Kuiper Belt. (The same scenario I described a year ago (on this page) which could have taken place with Triton/Pluto/Charon).
To date 2007 TY430 is the only ultra-red, equal-sized binary known outside of the classical Kuiper belt population. Numerical simulations suggest 2007 TY430 is moderately unstable in the outer part of the 3:2 resonance and thus 2007 TY430 is likely an escaped “cold” classical object that later got trapped in the 3:2 resonance.
@ChasAstro brings up a great point about this scenario he asked this.
"I’m not sure that the tidal dissipation mechanism you mention would be able to bring Triton’s orbit into the plane of Neptune’s equator because Neptune is so gassy. It’s atmosphere probably wouldn’t dissipate enough energy to change Triton’s orbit. If that mechanism worked for gas giant planets shouldn’t Iapetus also orbit in line with Saturn’s equator, rather than at 15.5 degrees?"
Great question.
The equatorial gravitational torque force induced by a parent planet is reduced by the square of its distance. My best guess answer comes in two words distance and resonance.
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The major axis is the longest diameter of an ellipse while the minor axis is the shortest.
The semi major axis is the longest orbital distance from the center of one body to another. Essentially, it is the radius of an orbit at the orbit's most distant point. |
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Our Moon's avg semi major axis around Earth
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384,402 km (238,856 miles)
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Triton's semi major axis around Neptune
Titan's semi major axis around Saturn
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354,759 km (220,437 miles)
1,221,870 km (759,235 miles)
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Iapetus' semi major axis around Saturn
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3,560,820 km (2,212,591 miles)
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Charon's semi major axis around Pluto
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19,591 km (12,173 miles)
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Triton is much closer to Neptune than Iapetus is to Saturn by about 2 million miles. Triton is even a little closer to Neptune than our Moon is to Earth and Neptune's mass is 17 times greater than that of Earth. Iapetus is 10 times further away from Saturn as Triton is from Neptune. This distance plays a major role in tidal flex dissipation via gravitational torque force.
What does it mean to say Saturn's gravitational torque force is reduced by the square of its distance?
It means that Saturn's gravitational influence is a hundred times less on Iapetus than it would be on Triton if Triton were orbiting Saturn at its current distance from Neptune. Iapetus being 10 times further away experiences 100 times less gravitational torque force allowing it to experience resonant perturbations that bump it into an inclined orbit of 15.5 degrees relative Saturn's equator. In other words, the gravitational pulsing perturbation bumps exercise more influence over Iapetus' orbit than Saturn's aligning pull due to its equatorial bulge.
Update 7/12/2018 I used the formula of the mass of object one times the mass of object two divided by the distance between them squared to get the actual force of gravity felt on Triton by Uranus vs Iapetus by Saturn. Iapetus feels a gravitational force from Saturn of 8.35 x 10^35 while Triton feels a gravitational force from Neptune of 1.74 x 10^37. Which means based on their actual mass and orbital distance, Neptune tugs on Triton 21 times harder than Saturn tugs on Iapetus.
Close proximity to Neptune will cause stronger twisting and torque forces when Triton's axis wobbles. On top of that Triton is despinning, its retrograde orbit is putting the brakes on its spin which is creating internal heat.
Bodies further away from the parent planet tend to behave more radically or independently (with inclined orbits relative to the parent bodies equator). Captured bodies further from the gravitational influence of the orbited body take longer to settle into an equatorial zone as the parent bodies gravitational torque is much reduced by distance just as Pluto is more perturbed and influenced by Neptune's nearby gravitational influence than by the Sun's. Similar to how Uranus is titled 90 degrees as are its moons relative to the ecliptic plane. While the Sun's size dwarfs Uranus and Neptune, their small moon's close proximity, relative to their proximity to the Sun, impart a larger gravitational torque on their nearby satellites than the Sun because they are closer and the Sun's gravitational energy loss dissipates by the square of its distance.
What does it mean to say Saturn's gravitational torque force is reduced by the square of its distance?
It means that Saturn's gravitational influence is a hundred times less on Iapetus than it would be on Triton if Triton were orbiting Saturn at its current distance from Neptune. Iapetus being 10 times further away experiences 100 times less gravitational torque force allowing it to experience resonant perturbations that bump it into an inclined orbit of 15.5 degrees relative Saturn's equator. In other words, the gravitational pulsing perturbation bumps exercise more influence over Iapetus' orbit than Saturn's aligning pull due to its equatorial bulge.
Update 7/12/2018 I used the formula of the mass of object one times the mass of object two divided by the distance between them squared to get the actual force of gravity felt on Triton by Uranus vs Iapetus by Saturn. Iapetus feels a gravitational force from Saturn of 8.35 x 10^35 while Triton feels a gravitational force from Neptune of 1.74 x 10^37. Which means based on their actual mass and orbital distance, Neptune tugs on Triton 21 times harder than Saturn tugs on Iapetus.
Close proximity to Neptune will cause stronger twisting and torque forces when Triton's axis wobbles. On top of that Triton is despinning, its retrograde orbit is putting the brakes on its spin which is creating internal heat.
Bodies further away from the parent planet tend to behave more radically or independently (with inclined orbits relative to the parent bodies equator). Captured bodies further from the gravitational influence of the orbited body take longer to settle into an equatorial zone as the parent bodies gravitational torque is much reduced by distance just as Pluto is more perturbed and influenced by Neptune's nearby gravitational influence than by the Sun's. Similar to how Uranus is titled 90 degrees as are its moons relative to the ecliptic plane. While the Sun's size dwarfs Uranus and Neptune, their small moon's close proximity, relative to their proximity to the Sun, impart a larger gravitational torque on their nearby satellites than the Sun because they are closer and the Sun's gravitational energy loss dissipates by the square of its distance.
Wiki quote
The moons of Saturn are typically thought to have formed through co-accretion, a similar process to that believed to have formed the planets in the Solar System. As the young gas giants formed, they were surrounded by discs of material that gradually coalesced into moons. However, a proposed model on the formation of Titan suggests that Titan was instead formed in a series of giant impacts between pre-existing moons. Iapetus and Rhea are thought to have formed from part of the debris of these collisions. More-recent studies, however, suggest that all of Saturn's moons inward of Titan are no more than 100 million years old; thus, Iapetus is unlikely to have formed in the same series of collisions as Rhea and all the other moons inward of Titan, and—along with Titan—may be a primordial satellite.
Wiki suggests Iapetus is debris from giant impacts between pre-existing moons. but new theories put this idea to the test.
These two papers explain the theory behind the inner moons (between Saturn & Titan's orbit) being no more than 100 million years and the resonance of Hyperion and Iapetus to Titan as well as Iapetus' 15.5 degree inclination.
Titan-Hyperion Resonance and the Tidal Q of Saturn
By Matija Cuk, Like Dones and David Nesvorn´y
Excitation of the Orbital Inclination of Iapetus during Planetary Encounters
By David Nesvorn'y, David Vokrouhlick, Rogerio Deienno, and Kevin J. Walsh
The second paper explains how Iapetus is just outside the Laplace radius of Saturn. This is the radius at which Saturn's gravitational grip is loosened enough such that the Sun's grip begins to have an effect on the small satellite's orbit. Saturn's obliquity or axial tilt angle is 27 degrees, its orbital inclination relative to the ecliptic is 2.5 degrees. Iapetus' inclination is 17 degrees to the ecliptic plane and 15.5 to Saturn's equator putting it pretty much smack dab in the middle of the Sun's equatorial plane and Saturn's.
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Iapetus orbits halfway between Saturn's equator and the equator of the Sun and sits right at the edge of the Laplace radius of Saturn.
I could stop here but there's more to learn from this moon. |
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Iapetus orbital inclination relative to moons inward to Saturn
Iapetus orbital distance from Saturn
Saturn's moon Titan is massive compared to all the others.
Several tiny moons that orbit inside Saturn's rings are forming by acting like a vacuum cleaner sucking up ice particles from the rings. They exhibit a round central bulge shape with a flat disc extending around their equator. This disc is formed by accretion. Three of these tiny moons are named Atlas, Daphnis and Pan. 
Atlas , Daphnis & Pan to scale with equatorial ridges formed by the accreted ices from Saturns rings
Atlas Saturn's ring accretion moon just outside the A ring
Pan accumulating and clearing ice creating a gap in the rings of Saturn
Pan closeup with accreted material creating an equatorial ridge
Iapetus with an equatorial ridge even though its too far from Saturn now to have acquired it from this distance.
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Iapetus has an equatorial ridge 20km or 12 miles high and is thought to be created by the accretion of ices similar to what we see on Saturn's moons Atlas and Pan. This suggests Iapetus was at some point closer to Saturn and inline with its orbital plane collecting ices from ring material.
Titan is 96% of Saturn's moons total mass. Six moons including Iapetus make up 4% while 55 moons make up a mere .04%.
Prometheus perturbing ice particles in Saturn's F ring followed by Atlas near the A ring.
Daphnis with equatorial bulge developing around an elongated core
Daphnis perturbing and clearing ice within the A ring.
Pan Saturn moon accreting material around equator
Iapetus is compositionally the same as the other small moons of Saturn while Titan is different suggesting Titan is a captured moon not an in-situ (in place) accreted moon. The ridge on Iapetus strongly suggest accretion took place previously which implies Iapetus was orbiting much closer to Saturn and in line with its equatorial plane at an earlier date. |
Some scientists believe the ridge around Iapetus' equator was formed as the result of Iapetus collapsing under its own gravitational force. But this ridge only runs three quarters of the way around Iapetus. Iapetus is tidally locked to Saturn (one side always faces Saturn) but Hyperion which is much closer to Saturn is not. Moon's closer to a planet tidally lock more rapidly than those that are farther away.
The equatorial bulge on Iapetus only exists on the dark side of Iapetus which is its leading hemisphere. Another current theory suggests this bulge was created from a ring of material that encompassed Iapetus but, again, the ring only exists around three quarters of the moon. Since Iapetus is tidally locked, its more reasonable to assume Iapetus was closer to Saturn at some point and scooped up material along its leading hemisphere from a ring of material orbiting Saturn.
The equatorial bulge on Iapetus only exists on the dark side of Iapetus which is its leading hemisphere. Another current theory suggests this bulge was created from a ring of material that encompassed Iapetus but, again, the ring only exists around three quarters of the moon. Since Iapetus is tidally locked, its more reasonable to assume Iapetus was closer to Saturn at some point and scooped up material along its leading hemisphere from a ring of material orbiting Saturn.
The scientists that produced the (above linked) recent studies indicating the inner moons of Saturn are less than 100 million years also indicate there was a previous resonance between Titan, Hyperion and Iapetus.
This resonance could explain the 15.5 degree inclination of Iapetus to Saturn's equatorial plane just like Neptune's 3:2 resonance with Pluto explains it's 17 degree inclination to the ecliptic plane. Iapetus' density is 1.088 g/cm3 indicating it is almost entirely made of water ice strongly suggesting it is accreted from Saturn's water ice ring material. Whereas, Titan is more like Pluto with a density of 1.854 g/cm3 indicating more rocky material and loads of nitrogen, methane and water ice and some carbon dioxide suggesting it is a captured object.
This resonance could explain the 15.5 degree inclination of Iapetus to Saturn's equatorial plane just like Neptune's 3:2 resonance with Pluto explains it's 17 degree inclination to the ecliptic plane. Iapetus' density is 1.088 g/cm3 indicating it is almost entirely made of water ice strongly suggesting it is accreted from Saturn's water ice ring material. Whereas, Titan is more like Pluto with a density of 1.854 g/cm3 indicating more rocky material and loads of nitrogen, methane and water ice and some carbon dioxide suggesting it is a captured object.
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This chart shows how moons become larger farther out from Saturn.
Iapetus' is the third largest moon of Saturn, its large size relative to other moons indicate it developed toward the outer edges of Saturn's inner rings. The fact that its bulging ridge only extends three quarters of the way around its equator suggests it was tidally locked when it was closer to Saturn just as it is today. Iapetus was likely an inner moon of Saturn until something resonantly perturbed or knocked it into a higher orbit. Titan sits between Saturn and Iapetus and is thus the likely candidate for this orbital perturbation. |
Atlas, Prometheus, Pandora, Epimetheus & Janus' Chart showing distance from Saturn with size. Closer moons tend to have more extended ridges.
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Hyperion is more than twice as close as Iapetus is to Saturn and is 0.003 times less massive (or 3 thousandths of a percent) and Hyperion is not tidally locked to Saturn while Iapetus is locked.
Smaller closer bodies lock sooner to their parent planet than larger farther bodies. Some scientists believe Hyperion is not locked to Saturn because Titan delivers resonant pulses to Hyperion but this doesn't make sense as a resonant pulse would more likely induce orbital oscillations (eccentricity) not just axial spin perturbations. If Hyperion at its current close distance and small mass relative to Iapetus is spinning but Iapetus is locked it says to me that Iapetus was closer to Saturn at one point, its spin got locked but then its orbit was perturbed by Titan into its current location where it remains locked with a bulging ridge along its leading hemisphere's equator from accreted Saturn ring ice particles. Distance from Saturn along with resonant pulses from Titan along with Iapetus being outside Saturn's Laplace radius could have all worked together to create Iapetus' inclined orbit. |
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If Titan is a captured not accreted moon which I think it is, then once it was introduced to the tiny moons of Saturn it could have easily nudged Iapetus into a higher orbit while the Sun's equatorial gravity pulled Iapetus' orbit relative to Saturn into a decreased inclination settling at 17 degrees.
I decided to test the consistency of the idea that Saturn's moons increase in size as they migrate further outward orbitally from Saturn. In the below image, I added moon diameter and orbital distance figures in yellow and from this we can see a direct correlation between the size of the moons and their orbital distance from Saturn. The size of Saturn's inner moons consistently increase with distance.
I decided to test the consistency of the idea that Saturn's moons increase in size as they migrate further outward orbitally from Saturn. In the below image, I added moon diameter and orbital distance figures in yellow and from this we can see a direct correlation between the size of the moons and their orbital distance from Saturn. The size of Saturn's inner moons consistently increase with distance.
Based on Iapetus' size it should be orbiting Saturn very near Rhea's orbital zone. This suggest the two were likely orbiting near each other at one point, Both Rhea and Iapetus are currently tidally locked to Saturn. Triton with its massive relative size and its compositional difference to all the other moons was likely captured and its gravitational influence perturbed Iapetus outward to just beyond Saturn's Laplace region and helped perturb it into a 17 degree inclination just like Neptune has done to Pluto/Charon.
Wiki says
Studies based on Enceladus's tidal-based geologic activity and the lack of evidence of extensive past resonances in Tethys, Dione, and Rhea's orbits suggest that the moons inward of Titan may be only 100 million years old.
This then suggests Iapetus may also be younger than 100 million years.
As a reminder, @ChasAstro asked this.
"I’m not sure that the tidal dissipation mechanism you mention would be able to bring Triton’s orbit into the plane of Neptune’s equator because Neptune is so gassy.
Wiki says
Studies based on Enceladus's tidal-based geologic activity and the lack of evidence of extensive past resonances in Tethys, Dione, and Rhea's orbits suggest that the moons inward of Titan may be only 100 million years old.
This then suggests Iapetus may also be younger than 100 million years.
As a reminder, @ChasAstro asked this.
"I’m not sure that the tidal dissipation mechanism you mention would be able to bring Triton’s orbit into the plane of Neptune’s equator because Neptune is so gassy.
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Considering the proximity of our Earth and Moon to the Sun's gravitational influence, Earth has pulled our Moon as close to the equator as it can. Our Moon is a little farther away from Earth (384,399 km) than Triton is from Neptune (354,759 km).
Our Moon has about three times the mass (7.342×10^22 kg) of Triton (2.14×10^22 kg) (heavier objects are harder to move) so it would be more difficult for our Earth's gravity to place the Moon around its equator than it would be for Neptune to adjust Triton around its equator but then there's also the matter of the parent body's mass. |
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If our Earth with 17 times less mass (hence less gravitational influence) can set our Moon which is 3 times the mass of Triton along its equator where our Moon is slightly farther away then I'm confident Neptune can also accomplish this task with Triton. All this info suggests Neptune has the mass and gravitational power to align Triton with its equator and given enough time, it will, further suggesting Triton was captured less than a billion years ago.
Back to Triton and Neptune.
I'll just add this quote from NASA regarding Triton and let it stand on its own.
"Tidal forces from its (Triton's) lopsided orbit are powerful enough to keep the interior active,"
Something had to slow the proto-Triton down as it wandered past Neptune;....a tremendous amount of heat would have been deposited in Triton's interior. That heat may not have been enough to explain the active surface we see today, but tidal forces from its lopsided orbit are powerful enough to keep the interior active, leading to eruptions of icy material onto the moon's surface and a redistribution of mass in its interior.
NASA doesn't go into any further detail so I will take it at face value that there are tidal forces in play. I don't fully understand how a near circular orbiting object like Triton is generating tidal forces except to explain them from the quote above by "Ask an Astronomer" (green text) along with NASA's lopsided orbit scenario so I will simply accept that it does.
Thanks for the help and feedback @ChasAstro, much appreciated.
Updates June 13th 2017
In July 1979 this below blue text article was created and the abstract is found in Science Direct
Pluto and the chaotic satellite system of Neptune may have originated from a single encounter of Neptune with a massive solar system body. A series of numerical experiments has been carried out to try to set limits on the circumstances of such an encounter. These experiments show that orbits very much like those of Pluto, Triton, and Nereid can result from a single close encounter of such a body with Neptune. The implied mass range and encounter velocities limit the source of the encountering body to a former trans-Neptunian planet in the 2- to 5-Earth-mass range.
They are suggesting a large object impacted Neptune creating the moons Pluto, Triton and Nereid in orbit around Neptune.
Then there's this letter to Nature by Bill McKinnon dated 1984
Lyttleton hypothesized long ago that Triton and Pluto originated as adjacent prograde satellites of Neptune. With the presently accepted masses of Triton and Pluto–Charon, however, the momentum and energy exchange that would be required to set Triton on a retrograde trajectory is impossible. The mass of Triton has probably been seriously overestimated, but not by enough to relax this restriction. It is implausible that the present angular momentum state of Pluto–Charon has been significantly influenced by Neptune. It could not acquire such angular momentum during an ejection event unless a physical collision was involved, which is quite unlikely.
Based on Bill's comments, It appears Lyttleton in 1936 thought Pluto and Triton were moons of Neptune at one point and a collision between Pluto and Triton sent Triton into a retrograde orbit and kicked out Pluto. In 1984 Bill is arguing against this concept primarily on the basis Pluto and Caron couldn't have been kicked out together.
My suggestion of their formation is completely opposite this scenario. I'm suggesting Triton/Pluto were Classical KBO perturbed by Neptune into their current orbits. Obviously I'm not the first to see the similarities of Triton and Pluto along with their potentially interactive past (another article on Pluto/Triton). Astronomer Marc Buie answers questions about Pluto of which this is one.
I think my approach is different though as all the articles I've read so far suggest Pluto was once a moon of Neptune ejected outward whereas I'm suggesting it never was a Neptune moon but rather Pluto/Triton/Charon were Kuiper Belt Objects, Neptune's perturbations and resonant pulses pushed Charon into an encounter with the Pluto/Triton binary system upsetting the apple cart dropping Triton into Neptune's orbit.
Update June 15th 2o17
Icy Satellite Processes in the Solar System
Neptune's system is a special case because of the likely capture process of Triton (Asphaug et al., 2006), which probably caused major disturbances of a previously existing satellite system. Triton's likely capture suggests an early history affected by tidal flexure and heating, though tidal processes are probably not significant in the current era (Chyba et al., 1989).
This paper suggests, when Triton was first captured by Neptune there were relevant heat induced tidal flexing forces at play which today are likely not significant. Triton is still volcanically active has a relatively smooth thin surface crust looking similar to Pluto at Sputnik Planitia. Science papers all make the same assumption, Triton was captured long long ago so tidal dissipation couldn't be driving current processes. I'm suggesting these processes took place much more recently and that's why we still see current activity on both Triton and Pluto.
Back to Triton and Neptune.
I'll just add this quote from NASA regarding Triton and let it stand on its own.
"Tidal forces from its (Triton's) lopsided orbit are powerful enough to keep the interior active,"
Something had to slow the proto-Triton down as it wandered past Neptune;....a tremendous amount of heat would have been deposited in Triton's interior. That heat may not have been enough to explain the active surface we see today, but tidal forces from its lopsided orbit are powerful enough to keep the interior active, leading to eruptions of icy material onto the moon's surface and a redistribution of mass in its interior.
NASA doesn't go into any further detail so I will take it at face value that there are tidal forces in play. I don't fully understand how a near circular orbiting object like Triton is generating tidal forces except to explain them from the quote above by "Ask an Astronomer" (green text) along with NASA's lopsided orbit scenario so I will simply accept that it does.
Thanks for the help and feedback @ChasAstro, much appreciated.
Updates June 13th 2017
In July 1979 this below blue text article was created and the abstract is found in Science Direct
Pluto and the chaotic satellite system of Neptune may have originated from a single encounter of Neptune with a massive solar system body. A series of numerical experiments has been carried out to try to set limits on the circumstances of such an encounter. These experiments show that orbits very much like those of Pluto, Triton, and Nereid can result from a single close encounter of such a body with Neptune. The implied mass range and encounter velocities limit the source of the encountering body to a former trans-Neptunian planet in the 2- to 5-Earth-mass range.
They are suggesting a large object impacted Neptune creating the moons Pluto, Triton and Nereid in orbit around Neptune.
Then there's this letter to Nature by Bill McKinnon dated 1984
Lyttleton hypothesized long ago that Triton and Pluto originated as adjacent prograde satellites of Neptune. With the presently accepted masses of Triton and Pluto–Charon, however, the momentum and energy exchange that would be required to set Triton on a retrograde trajectory is impossible. The mass of Triton has probably been seriously overestimated, but not by enough to relax this restriction. It is implausible that the present angular momentum state of Pluto–Charon has been significantly influenced by Neptune. It could not acquire such angular momentum during an ejection event unless a physical collision was involved, which is quite unlikely.
Based on Bill's comments, It appears Lyttleton in 1936 thought Pluto and Triton were moons of Neptune at one point and a collision between Pluto and Triton sent Triton into a retrograde orbit and kicked out Pluto. In 1984 Bill is arguing against this concept primarily on the basis Pluto and Caron couldn't have been kicked out together.
My suggestion of their formation is completely opposite this scenario. I'm suggesting Triton/Pluto were Classical KBO perturbed by Neptune into their current orbits. Obviously I'm not the first to see the similarities of Triton and Pluto along with their potentially interactive past (another article on Pluto/Triton). Astronomer Marc Buie answers questions about Pluto of which this is one.
I think my approach is different though as all the articles I've read so far suggest Pluto was once a moon of Neptune ejected outward whereas I'm suggesting it never was a Neptune moon but rather Pluto/Triton/Charon were Kuiper Belt Objects, Neptune's perturbations and resonant pulses pushed Charon into an encounter with the Pluto/Triton binary system upsetting the apple cart dropping Triton into Neptune's orbit.
Update June 15th 2o17
Icy Satellite Processes in the Solar System
Neptune's system is a special case because of the likely capture process of Triton (Asphaug et al., 2006), which probably caused major disturbances of a previously existing satellite system. Triton's likely capture suggests an early history affected by tidal flexure and heating, though tidal processes are probably not significant in the current era (Chyba et al., 1989).
This paper suggests, when Triton was first captured by Neptune there were relevant heat induced tidal flexing forces at play which today are likely not significant. Triton is still volcanically active has a relatively smooth thin surface crust looking similar to Pluto at Sputnik Planitia. Science papers all make the same assumption, Triton was captured long long ago so tidal dissipation couldn't be driving current processes. I'm suggesting these processes took place much more recently and that's why we still see current activity on both Triton and Pluto.
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This seems similar to what I've suggested happened with Pluto. Pluto was in an eccentric dance with Charon which previously generated relevant tidal flex energy but is now not significant. But both Pluto and Triton still show signs of recent activity suggesting to me they both could have been involved in the same process around the same time and not 4 billion years ago based on Triton's orbital inclination dating this process at less than 1 bya. Triton's surface is mostly smooth meaning the crust is too thin to support mountains and is renewing itself. The surface is relatively young yet we see black streaks on it indicating much younger volcanic eruptions have deposited the black mineral based material on top of a young surface. |
Triton with dark blotches of rocky mineralized gasses released from cryovolcanic activity
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Triton's current activity is significant enough to drive dark minerals up and onto the surface while thinning or overturning the ice crust. My theory without all the science detailed stuff goes like this.
- Pluto and Triton were a binary pair in the Kuiper belt minding their own business.
- Charon's zone of origination was closer to the giant planets (15-25 AU) and was pushed by Neptune into a hot Plutino zone inclined at 17% and in a 2:3 resonance with Neptune.
- Neptune eventually perturbed the Pluto/Triton binary pair out of their cold classical Kuiper belt < 5 degree circular orbit and into a more inclined hot inclination and 2:3 resonant orbit.
- Neptune caused Pluto/Triton and Charon to encounter each other.
- Once the three got together, one had to go.
- Triton was the looser of the tidal flexing orbital dance amongst the three.
- This initial tidal flex dance started internal heating of all three bodies
- Per chance, Triton was ejected from the trio in such a way as to allow Neptune to grab it.
- This caused additional tidal flex energy on Triton as Neptune's extreme mass slammed the brakes on Triton's direction of travel and spin similar to the hot screeching of tires when a car's brakes are slammed to the floor.
- This extreme braking of rotational and orbital direction fully differentiated the rock from ices on Triton and much of its outer ices were boiled (evaporated/sublimated) away making its current core activity of boiling minerals easily deposited onto the surface's thin ice crust in turn making Triton more dense than Pluto.
- Pluto/Charon went on their 2:3 resonant merry way with far less tidal flex energy available shared between them and hence don't show dark mineral cryovolcanic plume deposits on their surfaces.
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You might want to read my Eruptions page 77 as it explains some significant information related to Triton and Pluto.
Update December 8th 2018 Approximately 2 years after writing this page, I read a science paper dated 2006 that hypothesizes the same theory I'm proposing for Triton's capture. Bummer!
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Here's the last sentence of the paper "We conclude that Triton was once a member of a binary and was captured as it made a close approach to Neptune.
