As we migrate further away from the Sun temperature drops and volatile ices tend to dominate the bodies of the solar system.
Near the Sun (less than 2 AU) where the terrestrial rocky planets reside, most of the volatile gasses (ices) are evaporated away into space, hence, we are left with an abundance of the harder metals and minerals with a relatively few of the more volatile gasses.
Earth Rocks come in three flavors
Melting points of Rock and metal
If you melt sand or silica dioxide (SiO2) and cool it rapidly such that it does not have time to form a crystal lattice structure, it becomes an amorphous glass such as obsidian or olivine.
Olivine is a SiO2 rock/glass that is green but some sands are silica rock/glass that is reddish/yellow/brown.
Obsidian is typically a black silica glass mixed with magnesium and/or iron.
In this image take note of how the asthenosphere is referred to as "plastic" (flexible, pliable), whereas, the mantle is "stiffer"
Felsic or Feldspar rocks are constructed primarily of lighter materials such as silica, sodium and potassium (sandy quartz) and are less dense (2.56 g/cm^3) than rocks that are more magnesium and iron rich.
Granite is a felsic rock.
Felsic rock makes up about 41% of the stuff you walk on, on Earth.
Feldspars (KAlSi3O8 – NaAlSi3O8 – CaAl2Si2O8) are a group of rock-forming tectosilicate minerals that make up about 41% of the Earth's continental crust by weight. Feldspars crystallize from magma as veins in both intrusive and extrusive igneous rocks and are also present in many types of metamorphic rock.
As we migrate deeper into the Earth's core;
While this pattern exists on rocky bodies like asteroids and dwarf rocky planets, it does not necessarily hold true for ice dominant bodies like comet 67P.
Water has a density of 1 g/cm^3, ice has a density of 0.916 and Comet 67P has a density of only 0.533. Its core has been compared to cotton candy.
This is a commonly expressed unreasonable explanation describing the Earth's core where crustal rigid rock migrates down through the mantle, heats then rises again in a process called convection.
Since colder fluids are more dense than warmer fluids it is depicted that the upper crystallized crust subducts down through the mantle dropping as a cold slab of rock falling through denser lava.
The problem with this scenario is that the less dense rock is a brittle crystalline (conductive) material that resides at the upper crust boundary of the lithosphere and is less dense than the material below.
Less dense crystallized conductive material does not sink down into more dense material just because its in a more fluid state.
Density increases toward the core.
Density defines the layers and because of pressure the mantle is stiffer than the plastic athenosphere
While this concept of convection currents apply to liquids of similar densities since temperature dictates density in fluids, it doesn't apply to solids as they are conductive in nature (they don't easily transfer heat).
A less dense solid rigid crust might possibly get pushed down via subduction to a small degree, however, it would quickly fracture and break at some point and remain at its upper less dense zone.
This less dense iron anvil (7.874 g/cm^3) getting pushed down into a bath of more dense liquid mercury (13.534 g/cm^3) serves as an example.
Meteorite types & ratios found on Earth
Stone 94% (silicate/magnesium oxide minerals).
Metal 5% (Iron/nickel) melted metals must have formed under heat and pressure inside a large bodied asteroid which was sometime later broken apart by an impact.
Two hundred and forty one meteorites were studied to understand the average ratio of each compound found inside. Knowing this gives a rough sense of what ratios of matter are floating around the solar system and subsequently the general ratios and compositions of larger potentially planetary bodies.
The suffix meaning of pallasite, meteorite, granite or chondrite in French is ite or Latin ita or Greek ites
"connected with or belonging to" = ite
When two or more basic elements are combined or bonded together, they are a compound.
Meteorite Composition ratios
The most abundant compounds inside meteorites are
A rare Pallasite meteorite named Fukang (once an asteroid)
Boundary Conditions: We observed multiple (olivine) inclusions hundreds of microns in length in Fukang.
These inclusions contain a Cr-rich silicate (Cr=chromium), silica crystals, and k-rich (k=potassium) orthoclase-normative glass. We identified the silica crystals as monoclinic tridymite.
The presence of tridymite provides a constraint on the size of the pallasite parent body since tridymite is a SiO2 polymorph that only crystallizes in a narrow range of pressures (<0.40 GPa) and temperatures (870–1470 °C).
The pressure stability for tridymite varies in the literature (0.15 – 0.40 GPa) due to the presence of impurities that catalyze its formation.
Pallasite is a metal/rock meteorite with olivine crystals encased in melted iron which means these types of meteorites formed between temperatures of 1,536 °C (greater than iron’s melting point) & 1,900 °C (less than olivine’s melting point).
The presence of tridymite in Fukang further narrows the melting temperature and pressure under which it developed.
The temperature of normal mafic (magnesium – ferric (iron)) or surface ejected basaltic lava on Earth is 700 to 1,200 °C (too cool to melt iron and form a pallasite meteorite).
Jupiter’s moon Io on the other hand expels ultramafic lava which is 1,700 to 2,000 °C.
Pallasite meteorites could potentially exist at Io surface conditions but for inclusions of tridymite to form, a pallasite meteorite needs specific temperature AND pressure conditions, hence, a meteorite like Fukang had to form deep inside its parent body.
The temperature and pressure range for producing pallasite meteorites with tridymites presents a somewhat singular scenario for its development.
Most scientists for the past 30 years have felt the asteroid belt is leftover material from the solar system's formation which never successfully came together as one planet. But recent scientific studies demonstrate this is not the case and tridymite in pallasite meteorites is simply more corroborating evidence of this fact.
HED meteorites are all thought to have originated from the crust of the asteroid Vesta, their differences being due to different geologic histories of the parent rock. Their crystallization ages have been determined to be between 4.43 and 4.55 billion years from radioisotope ratios. HED meteorites are differentiated meteorites, which were created by igneous processes in the crust of their parent asteroid.
HED meteorites are a subgroup of achondrite meteorites.
Sixty percent of achondrite meteorites are HED.
They were formed under igneous (magma or lava) conditions
HED is an acronym of Howardite, Eucrite and Diogenite type meteorites
Hypervelocity impact processes are uniquely capable of generating shock metamorphism, which causes mineralogical transformations and deformation that register pressure and temperature conditions far beyond even the most extreme conditions created by terrestrial tectonics.
The mineral zircon (ZrSiO4) responds to shock deformation in various ways, including crystal-plasticity, twinning, polymorphism (e.g., transformation to the isochemical mineral reidite)
Reidite is a very rare altered zircon mineral formed under extreme pressure and temperature induced by impact shock waves, the same kind of impact shock waves that form Howardite.
One astronomical unit (AU) is the distance from Earth to the Sun and is used as a simple solar system measurement standard. Mars' is about 1.5 AU from the Sun.
Apollo asteroids are a group of Near Earth Objects (NEO) that orbit closer to the Sun than Mars (less than 1.1 AU) and could potentially impact with Earth some day but not anytime soon.
Ryugu is a NEO Apollo asteroid.
Apollo asteroids cross the orbital path of Earth.
Asteroids in the main asteroid belt are beyond Mars' orbital path (2-3.5 AU).
Within the asteroid belt, there is a zone where objects transition from rocky silicate magnesium oxide dominant bodies to organic carbon based water ice rich bodies.
This zone is called the frost line because the Sun's radiative energy is too weak to evaporate water ices as the temperature drops. Beyond the frost line, bodies tend to be more ice rich, at least from a volume standpoint.
The asteroid belt, long purported to be just a jumbled hodge podge of rocks orbiting between Mars and Jupiter is now known to be a family of objects from 5 or 6 previous larger bodies.
In other words, there used to be basically 6 large bodies smaller than Mars which were driven to collision and self-destruction.
We partially know this because meteorites like Fukang could only develop inside a body with specific pressure and heat conditions.
It is also known by their spectrographic similarity and orbital resonance, inclination and eccentricity that these groups of objects once belonged together.
C-type 75% = (Carbon based water ice rich) occur most frequently at the outer edge of the asteroid belt, 3.5 astronomical units (AU) from the Sun, where 80% of the asteroids are of this type, whereas only 40% of asteroids at 2 AU from the Sun are C-type with Albedos in the 0.03 to 0.10 range (Extremely dark). Any asteroid containing carbon (carbonaceous) is considered organic because all organic material is built from carbon.
S-type 17% = (Silica stony, (SiO2) aka quartz or sand, water poor) with albedos typically around 0.20 (moderately bright) consists mainly of iron and magnesium-silicates. They are dominant in the inner part of the asteroid belt within 2.2 AU, common in the central belt around 3 AU, but become rare farther out.
M-type 8% = (Metal mixed with stone) moderately bright (albedo 0.1–0.2).
Albedo is the amount of light hitting a surface relative to the amount reflected off a surface. It’s a ratio of emitted vs absorbed/scattered light. A hundred percent of light reflected off a surface equals a bond albedo of 1.
Bond albedo is the ratio of the total flux (fluctuating inflowing light) reflected and scattered in all directions, to that incident (angle). Incident light is the available light from a source while the reflected light is the incident minus the absorbed/scattered light.
For example, Saturn's moon Enceladus' bond albedo = 0.81.
Out of 100 photons hitting Enceladus only 81 reflect so 81/100 = 0.81 albedo.
Geometric albedo differs from bond albedo in that it is the ratio of the flux (fluctuating light) reflected head-on to that incident (available light).
Enceladus' geometric albedo is 1.4.
How can Enceladus reflect more than 100% light received?
In this table >>>>>>>>>>
Plutinos = objects in 3:2 resonance with Neptune.
Comets = ice dominant bodies beyond 3 AU
Centaurs = exist between 5 AU and 30 AU
SDO's = Neptune Scattered Disk Objects
Cubewanos = Kuiper Belt Objects 30-50 AU
Trojans = objects in 60° lead/lag L4,L5 Lagrange zone
To easily remember the difference between a Trojan object and a Centaur. Trojan's (like a horse) run 60° ahead of and behind planets
Centaurs are a mix of asteroids (mythical half man, half horse) and comets scattered randomly among the outer gas giants.
Pluto is reddish brown while Charon is more blueish gray suggesting they are most likely from different zones in the solar system mixed together by Neptune in the same way Scattered Disk Objects are multicolored and scattered by Neptune.
Neptune's orbital path is thought to have migrated outward, as it did, it scrambled up the objects that got too close.
This then created the scattered disk objects SDO, the mixed colors of objects around the gas planets.
Neptune's migration also put a lot of objects into resonant pulses with it and probably caused Haumea to collide with something creating the blueish Haumea family of objects.
The bright albedo of the Haumea collisional family indicates this collision occurred within the last billion years.
Neptune's migration outward is also credited with creating the late heavy bombardment.
Neptune's migration outward wreaked havoc in our solar system.
There are long pass, wide, medium & narrow spectra filters identifying electromagnetic waves from 2,000-10,000 angstroms (aka 200-1,000 nm, or 0.2-1.0 microns).
Dips aka lines of absorption in the spectrograph occur as gasses absorb energy from light at specific points along the light spectrum.
These dips or darkened zones (lines of absorption) leave a finger print which identify elements and compounds.
In this image the dark absorption bands appear as lines of emission which occur as the result of emitted not reflected light.
Comet 67P is thought to have come from the Kuiper Belt (50 AU).
Comet 67P has a hard outer shell with at least 8 inches of dust with a very porous core similar in ways to an egg.
The unusually high porosity of the interior of the nucleus provides the first indication cometary growth could not have been from violent collisions, as these would have compacted the fragile internal material.
Comet 67P is also a bylobed object constructed of two roughly same sized and compositionally similar objects which grew individually then conjoined gently enough not to rupture their outer crusts' (egg shell).
Thirty percent of transneptunian binary pairs (TNB) are similar in size and composition page 66.
It appears, similar sized comets/asteroids with similar compositions that are mutually captured into a binary pair is relatively common in the Kuiper Belt. I suspect the reason has to do with the similarity in size/mass.
If one object is much larger than the other, the larger object will either eject or gravitationally attract the smaller object. similarly sized objects have similar mass with a similar centrifugal gravity breaking effect as they drift closer and closer.
As two bodies get closer in an orbital dance, their collective spin speed increases to preserve their angular momentum.
As they get closer to colliding and their spin velocity increases their centrifugal force (outward flinging) grows which in turn slows their impact speed.
Basically their closely related gravitational pull (escape velocity) causes a somewhat balanced centrifugal orbital velocity that cancels against each other nullifying the (collision velocity) affect of their individual gravitational pull.
This, I suspect, is how an object like comet 67P constructed of two cotton candy like interiors and a brittle outer shell could survive the merge between these similarly sized objects.
Meteorites on average are 94% stone, of that stone 86% is chondritic (round pebbles and space dust), 8% of the stone is achondritic (cooled lava from a differentiated core body).
This chart shows the relative amount of potasium (K) and uranium (U) on various solar system bodies.
Chondrites contain less Uranium (1/100 gram per ton of rock) than Potasium (10^2.7 grams about one pound/ton of rock) than any other type of listed body while basaltic achondrites contain more U than K. In other words 86% of meteorite material contains larger quantities of K than U as a radiogenic heat source.
From this paper The K/U ratio of the silicate Earth: Insights into mantle composition, structure and thermal evolution I pulled the below chart showing the relative contribution of U, K and Th radiogenic heating of our Earth's core.
Potassium's contribution to Earth's heat has been decreasing steadily. Today it is contributing less than 20% of the heat provided by radioactivity.
Eighty six percent of the material in meteorites (chondrites) which contain a higher ratio of potassium relative to uranium is only contributing 20% of the heat from radiation.
If these values can be extrapolated to Pluto and if Pluto has a differentiated core then potassium would be the most abundant radioactive material in its core providing the least amount of heat energy to that core.
The dominant available quantity of radiogenic material (K) inside Pluto is currently providing the least amount of heat.
This is what F. Nimmo was saying prior to the flyby, however, today with no additionally supportive data he supports the hypothesis that there is a subsurface ocean created by a radioactively hot core.
The only thing added since these statements by Nimmo and McKinnon are models bent and twisted to create single minded outcomes while ignoring some basic fundamental observational facts.
Objects in a Neptune orbital resonance with radius larger than 600-700 km tend to be brighter (higher albedo) than non resonant objects suggesting resonance is the engine driving their resurfacing not radioactivity.
There are exceptions to every rule but the trend exists.
Objects with bright albedos suggest their surfaces are renewed and there is a correlation with the renewed surfaces and their orbital interaction with Neptune.
Pluto is in a 3:2 resonance with Neptune.
The monkey speaks his mind.