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ragasssd
2015-Jul-15, 08:27 PM
This just in:

“There is no giant body that can be deforming Pluto on an ongoing regular basis to heat the interior,” he says, “so this is telling us you don’t need tidal heating to power” change on icy worlds –

So how the hell is Pluto not pock marked with craters?!

Mountains of water ice, eh?

How is any of this possible??!?

The New Horizons pics are insane.

antoniseb
2015-Jul-15, 08:36 PM
... So how ... is Pluto not pock marked with craters?! ...
Just speculating because you asked, and nobody knows for sure, but it could be that Pluto has a Methane and Nitrogen ice surface covering a sea of Methane, Nitrogen, and maybe Hydrogen with harder ices forming mountain islands above the sea, and that any new large impacts melt the surface and erase the older smaller craters.

Fiery Phoenix
2015-Jul-15, 09:07 PM
Phil speculates (http://www.slate.com/blogs/bad_astronomy/2015/07/15/pluto_and_charon_the_first_close_up_images.html) it could be radioactivity from subsurface rocks.

Also, I think this would be a more suitable discussion for Astronomy rather than Q&A, since we don't really know of or have any straight answers to this issue yet.

transreality
2015-Jul-15, 11:41 PM
Could it be possible that the reason the surfaces of pluto and charon look young is because they have not experienced the late heavy bombardment? If the late heavy bombardment is caused by the interaction of the gas giants drawing icy bodies from the kuiper belt into the inner system this wouldn't affect remaining planetoids in the kuiper belt to the same extent as the moons of the gas giants and the inner rocky planets.

WayneFrancis
2015-Jul-16, 08:08 AM
I've been looking at the images and thinking about the Pluto system. Would we really expect it to be as cratered as objects closer in? I know it is at closest approach but would we expect Kuiper belt objects to be as impacted as objects further in?

The whole system seems very weird from what we would have expected even just a few years ago. I'm getting really interested on the explanations of how the system could have formed.

Swift
2015-Jul-16, 01:19 PM
Also, I think this would be a more suitable discussion for Astronomy rather than Q&A, since we don't really know of or have any straight answers to this issue yet.
As I've told many a technician, if I knew the answer now, I wouldn't need to do the research. ;)

And now with the Admin hat - thread moved from Q&A to Astronomy

thoth II
2015-Jul-16, 03:29 PM
I think it is likely the lack of craters denotes a young surface, and so some energy source like radioactive decay in the silicate core must still be at work. Also, with such a thin vernier, the nitrogen coating at the surface probably is due to either cryovolcanism or geysers, and this is outgassing now.

Cougar
2015-Jul-16, 03:35 PM
So how the hell is Pluto not pock marked with craters?!

Here's another vote for interior radioactive heating:


Radioactive heating from within Pluto may drive geological activity and resurface this region with fresh material, says team member Veronica Bray, a planetary scientist at the University of Arizona in Tucson.

galacsi
2015-Jul-16, 06:28 PM
Here's another vote for interior radioactive heating:

Radioactive heating from within Pluto may drive geological activity and resurface this region with fresh material, says team member Veronica Bray, a planetary scientist at the University of Arizona in Tucson.



A very gratuitous supposition ,this scientific explanation ! Why the moon or Mars who are all silicate shows so little volcanic activity today if radioactive heating is the cause ?

transreality
2015-Jul-16, 11:55 PM
In the Pluto image the sharp looking mountains are streaked with dark material that has eroded channels in the ice. The active process likely is the seasonal formation of a methane/nitrogen atmosphere which is then subject to UV dissociation to form tholins, that deposit as dark material. This is possibly a very gradual process if it has continued for billions of years could result in covering craters, submerging mountains, and peaks streaked with gullies.

Ken G
2015-Jul-17, 02:43 PM
Maybe answers will come from comparing to the surfaces of the smaller moons of Pluto-- they should have the same recent bombardment history but different resurfacing effects.

bknight
2015-Jul-17, 07:37 PM
Also looks like the solar wind in blasting away at the thin nitrogen atmosphere.

http://www.nasa.gov/nh/pluto-wags-its-tail

DonM435
2015-Jul-17, 07:51 PM
Maybe answers will come from comparing to the surfaces of the smaller moons of Pluto-- they should have the same recent bombardment history but different resurfacing effects.

Will we be seeing the smaller moons as anything but big pixels?

thoth II
2015-Jul-17, 11:28 PM
I'm expecting the better resolution images of the moons will be coming in September. I thought I heard Alan Stern say that

Ross 54
2015-Jul-18, 03:01 PM
Both Pluto and Charon appear to be only very lightly cratered. An explanation applicable to both seems to be called for. Is there any indication that Charon also has an atmosphere that could be involved in long-term obscuration of its surface?
Then too, Charon would be an even unlikelier site of current radiogenic heat than Pluto.
Perhaps the giant impact on Pluto, which is thought to have created its system of moons, was unexpectedly recent; recent enough that the reworked surfaces have not had time to be substantially cratered.

Ken G
2015-Jul-18, 11:58 PM
That seems like a possible explanation, but then we need to accept that such a very improbable event could have occurred recently. There doesn't seem to be a whole lot out there to collide with!

Ross 54
2015-Jul-19, 01:08 AM
It's not clear that a relatively recent giant impact is less probable than a tidal or radiogenic heating scenario, in this setting. Pluto's eccentric orbit caries it through the most densely populated area of the Kuiper belt. An object of a mass sufficient to constitute a giant impact on Pluto could be much smaller, and so, much less improbable, than the giant impact thought to have affected Earth.

Ken G
2015-Jul-19, 03:24 AM
But the target is smaller too! I would expect the probability of a major collision is quite small, but of course I have no quantitative calculations to back that up. Since we expect Pluto to have been affected by a major collision, if that is our explanation of Charon for example, then the question moves to when did it happen. That's a probabilistic question, proportional to the timespan allowed, and the density of objects capable of making such a collision. Perhaps it is true that the late bombardment period is not relevant to the Kuiper belt, so we might not have such an early-weighted probability as we would for Mercury or Earth. But even so, if the solar system is 4.5 billion years old, one has at most a 1/5 chance a given collision would happen in the last billion years, and even less if you want to make it more recent than that. And then there's the problem of where are all the smaller objects that go along with a big one? In other words, anything one does to increase the probability of a recent major collision will also crank up the rate of recent minor collisions, such as would make craters. One has a problem with the ratio of big hits to small hits, unless one can fill in the small hits somehow.

Ross 54
2015-Jul-19, 03:37 PM
Given the discussed time frame of the last 100 million years, a simple probabilistic approach would suggest odds of a giant impact at Pluto of about 2 percent. It doesn't appear that we know enough about the long term dynamics of the Kuiper belt to rule out the possibility of something that could perturb those odds.
If a giant impact rendered Pluto molten, many smaller impacts at that time could conceivably have been absorbed without leaving a trace on the surface.
If it is finally conceded that radiogenic and tidal-frictional heating are inadequate explanations for Pluto's, and Charon's, relatively young surfaces, a relatively recent giant impact may turn out to be the most reasonable scenario.

Noclevername
2015-Jul-19, 04:12 PM
A very gratuitous supposition ,this scientific explanation ! Why the moon or Mars who are all silicate shows so little volcanic activity today if radioactive heating is the cause ?

Because silicates have a much higher melting temperature?

Ross 54
2015-Jul-19, 08:02 PM
The point was, I believe, that the radiogenic heating in a planet comes from the decay of radioactive elements in its crust and mantle. Both Mars and our Moon have much larger volumes of silicate crusts and mantles than does Pluto, yet they have shown no real evidence of current heat-driven geology. Expecting Pluto to have such activity seems unwarranted.

antoniseb
2015-Jul-19, 08:14 PM
... Expecting Pluto to have such activity seems unwarranted.
A couple of thoughts on this:
1. It would take much less radiogenic heating on Pluto to have a noticeable effect than it would on Mars or the Moon. The average vibrational energy of atoms on its surface is much less than 1% of that on the Moon, and the materials on the surface are much closer to the solid-liquid transition temperature.
2. I think the decay of radioisotopes anywhere crust, mantle, or core will all contribute equally to the heat flowing out of the celestial body.

Ken G
2015-Jul-19, 08:19 PM
I think your point 1 might be the crux of the issue here. Ross 54 is saying that the heat flux at the surface depends on the total volume of radioactives that have not yet decayed away, so relevant is the ratio of volume to surface area, and that shows up poorly on Pluto. But your point is that it's not just the heat flux that matters, but also what the heat flux does.

Ross 54
2015-Jul-19, 09:58 PM
It appears that Charon and Pluto have oddly young surfaces in common. Their close association suggests that this is not a coincidence. While Pluto appears to have some readily volatile substances on its surface, Charon's surface seems to be dominated by water ice. This is apparently expected to be rock stable at the available temperatures. It seem unlikely that a 750 mile (1200 km) -wide moon would have radiogenic heat sufficient to alter this situation significantly.

kzb
2015-Jul-20, 11:20 AM
Is it possible that tidal heating has been dismissed too quickly? After all Pluto has the largest satellite relative to its size in the solar system.

Is it also conceivable that the Pluto system has been perturbed by close encounters with Neptune in the past? Although the Pluto system has come back to equilibrium since, that would've lead to heat production.

Ross 54
2015-Jul-20, 03:24 PM
Since Pluto and Charon are mutually tidally locked, there seems to be little flexing of the materials of either body, so very little heat evolved in this way. The tidal deformations on both Pluto and Charon appear to remain in a single shape in the same areas of each body. There are seemingly no significant changing or moving tides.
With Pluto's orbit significantly inclined with respect to that of Neptune, a close encounter between the two in the past appears very unlikely.

Grey
2015-Jul-20, 03:35 PM
Is it possible that tidal heating has been dismissed too quickly? After all Pluto has the largest satellite relative to its size in the solar system.They're tidally locked, so that eliminates nearly all the tidal heating.

kzb
2015-Jul-20, 03:35 PM
Since Pluto and Charon are mutually tidally locked, there seems to be little flexing of the materials of either body, so very little heat evolved in this way. The tidal deformations on both Pluto and Charon appear to remain in a single shape in the same areas of each body. There are seemingly no significant changing or moving tides.
With Pluto's orbit significantly inclined with respect to that of Neptune, a close encounter between the two in the past appears very unlikely.

I'm wondering about the past though. The fact that Pluto and Neptune are in resonant orbits surely means there has been a lot of interaction in the past in order to get them into this state. The Pluto satellite system would then have to relax into its current condition. Admittedly a bit of a stretch to think this only completed 100 million years ago, but I thought it was worth raising.

thoth II
2015-Jul-20, 05:26 PM
I would expect a modest amount of heat from radioactive heating could produce the resurfacing effects we see on Pluto and Charon because they have icy mantles and crusts. This heat on Mars and moon wouldn't be sufficient to melt and resurface their rocky crusts.

Ross 54
2015-Jul-20, 10:35 PM
As far as I'm aware, no dynamical solutions were found that would allow past encounters between Neptune and Pluto, close enough to have a significant bearing on tidal friction. Apparently, eons ago, Neptune moved gradually outward toward the Kuiper belt and caused the stabilizing orbital resonances, and super-resonances with Pluto we still see today.
The Pluto system has a maximum temperature of ~ 55 K. The surface temperature of Charon would have to be raised by over 200 Kelvin to allow the water ice that is thought to dominate there to melt, and resurface an otherwise cratered crust. I am having trouble seeing how a moon 750 miles in diameter could muster enough radiogenic heat to accomplish this.

01101001
2015-Jul-20, 11:22 PM
Mike Brown, self-described @plutokiller, implies it might just be redistibuted frost that's hiding a more battered surface.

https://mobile.twitter.com/plutokiller


@cosmos4u @StarzanPlanets covered in frost. frost redistribution is not the same as internal geological activity.

But, wisely, he's mostly awaiting further data.

Ross 54
2015-Jul-21, 02:36 AM
Volatile nitrogen and carbon monoxide frosts don't seem to account for kilometers-high mountains of rock-stable water ice. These mountains are apparently judged to be quite young, so internal geological activity, and the difficulties this suggests still seem to be in play.

01101001
2015-Jul-21, 02:53 AM
Brian May posted a nice stereo pair of a look back at Pluto. The left image has enough resolution to show some of the probably more expected cratering on the left limb:

https://twitter.com/DrBrianMay/status/623297960558735360

antoniseb
2015-Jul-21, 12:05 PM
Brian May posted a nice stereo pair of a look back at Pluto.
Odd, when I look at it the 3D sense is exaggerated in my direction so it makes Pluto seem very long and I'm looking the short way. It makes the white spray going under it look very long.

Jeff Root
2015-Jul-21, 04:47 PM
Excellent! Wide-eyed stereo, not cross-eyed!

-- Jeff, in Minneapolis

Jeff Root
2015-Jul-21, 04:55 PM
Apparently, eons ago, Neptune moved gradually outward
toward the Kuiper belt
I'm pretty sure I asked this before, and got an answer,
but I have no memory of what the answer was.

How could Neptune -- or any planet -- move outward?
I can see how a planet could move inward if it ejects huge
masses of dust and gas or asteroids that do not fall back
to the planet's orbit. (Either by escaping the Solar System
or by their orbits getting circularized in the Oort Cloud.)

-- Jeff, in Minneapolis

thoth II
2015-Jul-21, 05:05 PM
A new image of 2 of pluto's moons:

https://www.nasa.gov/image-feature/new-horizons-captures-two-of-plutos-smaller-moons

Ross 54
2015-Jul-22, 12:58 AM
I'm pretty sure I asked this before, and got an answer,
but I have no memory of what the answer was.

How could Neptune -- or any planet -- move outward?
I can see how a planet could move inward if it ejects huge
masses of dust and gas or asteroids that do not fall back
to the planet's orbit. (Either by escaping the Solar System
or by their orbits getting circularized in the Oort Cloud.)

-- Jeff, in Minneapolis
In the very early solar system, the planets tended to jostle one another with their gravity fields. The current thinking seems to be that Jupiter moved inward, by interacting with interplanetary debris. It swept up some of these, the Sun blasted others away. It then became possible for Saturn to stop Jupiter's inward migration, and eventually pull it outward again. Jupiter and Saturn established a 1:2 orbital period resonance. This apparently caused Uranus and Neptune to be pushed outward. The latter planet eventually established the stable resonances with Pluto, referred to in a previous post. It is also though to have captured its largest moon Triton, formerly a Kuiper belt object.

Jeff Root
2015-Jul-22, 02:52 AM
It then became possible for Saturn to stop Jupiter's
inward migration, and eventually pull it outward again.
How? If Saturn was outside Jupiter's orbit, and Jupiter
moved inward due to flinging out a huge amount of
small stuff, then Jupiter and Saturn ended up farther
apart than they started out, where they would have
even less influence on each other.



Jupiter and Saturn established a 1:2 orbital period
resonance. This apparently caused Uranus and Neptune
to be pushed outward.
How? What is the mechanism?

-- Jeff, in Minneapolis

Zartan
2015-Jul-22, 08:27 AM
New pic (http://www.nasa.gov/image-feature/nasa-s-new-horizons-finds-second-mountain-range-in-pluto-s-heart) from Pluto's Pluto region...err I mean, Tombaugh region. This time showing border of between two regions. And this is very interesting: dark region is heavily cratered, very old, whereas light area again does not display a single impact crater. Some craters have been partially filled with light stuff. It looks like someone poured milk on the poor planet which then froze. Again there are mountains. It'll be interesting to see whether the dark areas also have mountains.

In last week's presser, there was some gentleman who remembered initial Mariner 4 results and described how disappointed people where that Mars turned out to be quite dead, cratered world like Moon (though in retrospect we were bit unlucky as Mariner 4 happened to see oldest regions of Mars). It seems after that, the expectation has always been that the worlds are dead & inactive and we're surprised when they're not (Io, Triton etc). However, now Pluto demonstrates much younger surface than expected, Saturnian moons have so much stuff going on we've managed to grasp only tiny portion of it, even Ceres shows hints of some kind of activity...the new default actually is that these worlds are "cryotectonically" (is that a real word?) active, and exception are those bodies which are not. So maybe we should rephrase the question "why are these worlds active?" to "why are those worlds not active?". Why are Callisto and Ganymede so inactive? Why the Uranian system appears so dead?

Tidal energy has been dismissed as source of energy for Pluto's activity, however is it actually possible that librations could nevertheless transfer some energy between the bodies? Do we know what kind of librations Pluto & Charon have and is it theoretically possible it might have some effect...but now when I check, apparently Charon's orbit is almost completely circular so I guess even that is out.
One last straw: Pluto and Charon are tidally locked to each other, so Charon always hangs over exact same spot of Pluto. Where precisely is that?

DonM435
2015-Jul-22, 02:46 PM
Wouldn't the sub-Charon point be logically chosen for Pluto's "Prime Meridian" when they draw up the maps?

kzb
2015-Jul-22, 04:01 PM
How? If Saturn was outside Jupiter's orbit, and Jupiter
moved inward due to flinging out a huge amount of
small stuff, then Jupiter and Saturn ended up farther
apart than they started out, where they would have
even less influence on each other.


How? What is the mechanism?

-- Jeff, in Minneapolis

The latest theory is that there must have been at least one large planet ejected from the early solar system to explain the current configuration. Don't ask me about the details though.

Pluto has a low average density (about 2g/cu cm) and has a lower proportion of heavy elements than the terrestrial planets. The radiogenic heating per unit volume of planet (if I can call it that) must be much lower because of this.

Ross 54
2015-Jul-22, 07:13 PM
How? If Saturn was outside Jupiter's orbit, and Jupiter
moved inward due to flinging out a huge amount of
small stuff, then Jupiter and Saturn ended up farther
apart than they started out, where they would have
even less influence on each other.


How? What is the mechanism?

-- Jeff, in Minneapolis
I'm no expert in orbital mechanics, but I interpret what i read, as follows: Close gravitational interactions with planetesimals caused Jupiter to gain momentum from them. Jupiter's increased velocity made it assume an orbit nearer the Sun. Once such interactions decreased in frequency, Saturn's gravity was now sufficient pull Jupiter back outward. It no longer had to compete with the effect of near encounters of Jupiter with planetesimals.

The 1:2 orbital resonance of Jupiter and Saturn presumably slowed Uranus, Neptune, and the Kuiper belt objects, whenever they were in conjunction from the point of view of the affected object, via their gravitational pull. This slowing would, it appears, force them into orbits further from the Sun.

Jeff Root
2015-Jul-22, 08:14 PM
This sounds all wrong. There might be nuggets of truth
in it, but overall it makes no sense to me.



Close gravitational interactions with planetesimals caused
Jupiter to gain momentum from them. Jupiter's increased
velocity made it assume an orbit nearer the Sun.
Jupiter should lose momentum (relative to the Sun) from
such interactions, causing it to fall closer to the Sun and
gain speed. This depends on the planetesimals or other
stuff being thrown permanently out of Jupiter's orbit, so
that it does not interact with Jupiter again. Jupiter can do
that because it is the only planet massive enough to give
stuff escape speed, and also because stuff it throws out to
the Oort Cloud can have its perihelion raised by tidal force
from the galaxy as a whole. That provides a mechanism
for Jupiter to move closer to the Sun.



Once such interactions decreased in frequency, Saturn's
gravity was now sufficient pull Jupiter back outward.
I don't believe it. It sounds totally loopy.



It no longer had to compete with the effect of near
encounters of Jupiter with planetesimals.
Sounds fishy to me.



The 1:2 orbital resonance of Jupiter and Saturn
presumably slowed Uranus, Neptune, and the Kuiper
belt objects, whenever they were in conjunction from
the point of view of the affected object, via their
gravitational pull. This slowing would, it appears,
force them into orbits further from the Sun.
That sounds like you've mixed up cause and effect.

If the immediate effect was to slow them, then they
would fall closer to the Sun where they would move
faster. If the immediate effect was instead to raise
their orbits away from the Sun, then they would be
moving more slowly in those new orbits. But maybe
you meant that the immediate effect was to speed
them up at each conjunction, which would raise their
orbits, so their overall speeds would then be slower.

I guess that sounds plausible. But if Jupiter pushed
Uranus, Neptune, and the Kuiper belt objects farther
from the Sun, then Jupiter had to fall closer to the
Sun at the same time.

-- Jeff, in Minneapolis
.

malaidas
2015-Jul-22, 11:11 PM
What is needed here is some valid citations to solve the issue. It sounds strange to me also, but if there is good scientific backing I'll accept it.

Eta: one huge question I have is this, I accept that an object under gravity would speed up, this also will tend to increase its orbit not decrease it surely?? The momentum of the object should tend to counteract the gravitational pull upon it's course, finding an equilibrium for its mass at a greater distance from the gravitational center of force.

Ross 54
2015-Jul-23, 01:34 AM
Well yes, as it turns out, my interpretation of what I read about solar system evolution went badly wrong. I respectfully suggest that no one try to make any sense out of what I wrote, and consult more reliable sources of information, instead. I'm sorry for any confusion I caused.

Jeff Root
2015-Jul-23, 11:15 AM
That's okay. I've been wanting to complain about that idea
for quite a while.

-- Jeff, in Minneapolis

Jeff Root
2015-Jul-23, 11:43 AM
malaidas,

When a small body is in a circular orbit around a larger one,
and you give the small body a shove so that it is momentarily
moving faster in the direction of its orbit, then it will rise away
from the larger body, slowing as it rises. Just like an object
you throw up in the air slows as it rises. When it reaches
apoapsis, it will be moving more slowly than it was originally.
It will be moving too slowly to remain at that altitude, and
begins falling back down, gaining speed again as it falls.
It falls and gains speed until it reaches periapsis, when it is
at the same altitude and moving at the same speed it had
just after it was given the shove.

The small body has been put into an elliptical orbit.

If instead of giving the small body a single big shove at one
point in its initial circular orbit, you shove on it very gently,
all along the orbit for many orbits, the body will gradually
spiral out to a higher circular orbit, moving more and more
slowly all the time.

While you are actually shoving it, the body will be moving
faster than the speed for a circular orbit at that altitude,
even though it keeps moving more and more slowly.

So going faster makes you go slower, and vice-versa.

-- Jeff, in Minneapolis

malaidas
2015-Jul-23, 12:26 PM
Cheers Jeff.

I can understand the elliptical explanation, there's a minor question I have about the circular one. When we say slower is it actually slower locally, or are we simply talking the time taken for an orbit? If the former I need to go back and study angular momentum more closely.

Ken G
2015-Jul-23, 04:38 PM
It's faster locally, like Jeff said its speed would always be very slightly above the circular orbit speed. But the speed would be dropping with time because it is fighting gravity more than it is getting helped by your gradual push. Since it is spiraling gradually outward, the circular orbit speed is also dropping with time, so that's how the actual speed can be dropping yet still stay above the circular speed (by a very small margin).

malaidas
2015-Jul-23, 05:00 PM
Cheers Ken.

Jeff Root
2015-Jul-23, 09:42 PM
A graph of how orbital speed varies with distance from Earth
is at http://www.freemars.org/jeff/speed/index.htm .

Orbital period isn't shown on the graph but is in the table.

The shape of the curve is odd because I wanted to show detail
in low Earth orbit but also include the relatively distant Moon,
so I put the origin of the logarithmic scale in a funny place,
15 km below Earth's surface. There may be a better way to
do it which doesn't result in the odd curve.

-- Jeff, in Minneapolis

malaidas
2015-Jul-23, 11:48 PM
Cheers Jeff, had a brief look, but will view properly tomorrow, when I am fresher.

thoth II
2015-Jul-24, 09:03 PM
https://www.nasa.gov/feature/new-horizons-discovers-flowing-ices-on-pluto

I would expect the flowing glaciers and polygon cells indicate some degree of heating is coming up from the interior. It will take them some time to find the origin of this heat.

Ross 54
2015-Jul-25, 04:58 PM
Some radial lines extending across the left side of the 'heart' feature on Pluto suggest the possibility of a large impact; they look rather like lightly coated crater rays. Such an impact could have been a considerable source of heat. It still seems difficult to connect this with the raising of kilometers-high mountains of ice, though.

Cougar
2015-Jul-25, 08:29 PM
I would expect the flowing glaciers and polygon cells indicate some degree of heating is coming up from the interior. It will take them some time to find the origin of this heat.

It's certainly interesting. :) I've read that since there's no tidal heating, internal natural radioactivity was promptly mentioned. (It seems related that one receives measurably more millirems of radioactivity if you live in a house on a cement foundation. This is pretty negligible, but seeping radon gas is not!)

But then there's this: "Pluto's atmosphere is replenished by ices that sublimate off its surface." And its atmosphere is detected out to 80 miles?! I guess if you never knew all that much about an object, you'd get surprise after surprise with a flyby. Major congratulations to all the team members that helped make happen and continue to make happen such an incredible achievement!

transreality
2015-Jul-26, 04:41 AM
Some of that atmosphere might then escape from Pluto, and end up accreting onto other moons of the system. Charons red spot?

galacsi
2015-Jul-26, 07:33 AM
Some of that atmosphere might then escape from Pluto, and end up accreting onto other moons of the system. Charons red spot?

And the contrary is also possible ,some volatiles escape from Charon , end on Pluto and resurface the (dwarf) planet.

Jerry
2015-Jul-26, 11:10 PM
Cheers Jeff.

I can understand the elliptical explanation, there's a minor question I have about the circular one. When we say slower is it actually slower locally, or are we simply talking the time taken for an orbit? If the former I need to go back and study angular momentum more closely. I think they mean a slower orbit; but at greater radial distance, so the angular momentum is greater. It is a 2pi verses r thing - so each increase of one in radius increases the angular velocity by 2pi; and the momentum has that ^2 multiplier as well. Jupiter could eject the Earth from the solar system with a loss of less than 4% of her momentum.

A body nearing another body can provide either gravitational acceleration or braking, relative to a third body; and since all planetary bodies are in elliptical orbits the net effects can move another planet nearer to, or further away from the sun; and as always, the 'third body' will accelerate opposite the second body.

Jeff Root
2015-Jul-27, 12:40 AM
A body nearing another body can provide either
gravitational acceleration or braking, relative to a
third body; and since all planetary bodies are in
elliptical orbits the net effects can move another
planet nearer to, or further away from the sun;
If Jupiter reduces the perihelion of a smaller body,
that smaller body will still have an aphelion at or
beyond Jupiter's orbit. So unless the smaller body
has its orbit changed by hitting some other planet
or the Sun or by the galaxy's gravity gradient, it
will continue to interact with Jupiter and will either
hit Jupiter or be kicked out of the Solar system.

I interpret that to imply that Jupiter gets a net
push inward, with a larger mass of small bodies
being thrown out and never returning than being
thrown in and never returning.

-- Jeff, in Minneapolis

Jerry
2015-Jul-27, 03:19 AM
What you describe is in a broad sense true, and also why it is difficult for a planetary system to become stable. But when there are resonant orbits (1:2, 1:3...ratios) the minor perturbations of other planets are self correcting: if the smaller body gets 'ahead' on one orbit, it will be pulled back. If it gets behind, it will be pulled ahead on the next pass. The establishment of resonance has an overall stabilizing effect; and this is why the resonance between Saturn and Jupiter is so important.

bknight
2015-Aug-09, 12:15 AM
If Jupiter reduces the perihelion of a smaller body,
that smaller body will still have an aphelion at or
beyond Jupiter's orbit. So unless the smaller body
has its orbit changed by hitting some other planet
or the Sun or by the galaxy's gravity gradient, it
will continue to interact with Jupiter and will either
hit Jupiter or be kicked out of the Solar system.

I interpret that to imply that Jupiter gets a net
push inward, with a larger mass of small bodies
being thrown out and never returning than being
thrown in and never returning.

-- Jeff, in Minneapolis
I was looking at ESA's web site and they had a diagram of Comet 67P. It occurred to me that since it intersects Jupiter's orbit twice there will be a good chance of either impact or ejection in the future. Has anyone done a calculation on an intercept?

antoniseb
2015-Aug-11, 12:18 PM
I was looking at ESA's web site and they had a diagram of Comet 67P. ...
I'm being too lazy to try and figure out who took this thread on Pluto this far off topic, but please keep your posts here about Pluto.

Jerry
2016-Jan-13, 07:09 AM
http://www.nasa.gov/image-feature/pluto-s-icy-plains-in-highest-resolution-views-from-new-horizons


Pluto’s surface geology alone – from the bladed terrain of Tartarus Dorsa to the mysterious dark mound of Morgoth Macula (just to mention a few informally named features with perplexing geologies) – continues to stump all of us on the New Horizons Geology and Geophysics Investigation (GGI) team...
...The dark materials are reminiscent of glacial moraines seen on Earth, but because this is Pluto, we have no idea what this dark material is, and whether or not the patterns we see are indeed moraines in the traditional terrestrial sense.

"Once you eliminate the impossible, whatever remains, no matter how improbable, must be the truth."


Sherlock Holmes/Arthur Conan Doyle


Read more at http://www.brainyquote.com/quotes/authors/a/arthur_conan_doyle.html#WYg2hoB8kRmjjPSv.99

Jerry
2016-Jan-14, 09:34 PM
http://www.nasa.gov/image-feature/pluto-s-wright-mons-in-color

This feature, known as Wright Mons, was informally named by the New Horizons team in honor of the Wright brothers. At about 90 miles (150 kilometers) across and 2.5 miles (4 kilometers) high, this feature is enormous. If it is in fact an ice volcano, as suspected, it would be the largest such feature discovered in the outer solar system...Mission scientists are intrigued by the sparse distribution of red material in the image and wonder why it is not more widespread.(my bold)

If this were the Earth or Mars, the placement of the red material would not be an enigma at all; as it lies underneath the snow-covered peaks. On the earth, the snow is ice, on Mars it is mostly CO2 ice. On Pluto it could be water, ice, methanol or even methane (IR images should tell us which). But on Pluto, it is the underlying strata that is vexing mission planetary scientists: It should not be red because there is not sufficient mass budget in Pluto for the surface to be dominated by Earth or Mars-like regoth.

So what is the red stuff? Mission scientists are speculating that it is 'tholins' - thin layers of nitrated hydrocarbons synthesized in the thin atmosphere. These organics are red in appearence; but only if it is found in very thin layers. (The natural synthesis process of 'tholins' yields many hydrocarbons, and more than a thin layer of 'tholins' becomes predominately black).

Of course, much of the strata elsewhere on Pluto is red, and if the thin-layer hypothesis is correct; we should see patterns where the underlying strata appear white with a thin red vale. As more color and broad spectrum images are streamed down and analyzed, the picture could become more clear or more clouded.

My hand is betting entirely on more clouded; or to be more specific: Evidence that points to very thick layers of red materials with snowy caps; and likewise for Charon.

eburacum45
2016-Jan-15, 09:38 AM
And the snail
http://www.chron.com/news/nation-world/space/article/NASA-pics-show-snail-like-objects-traversing-Pluto-6753343.php

Jerry
2016-Jan-19, 06:41 PM
And the snail
http://www.chron.com/news/nation-world/space/article/NASA-pics-show-snail-like-objects-traversing-Pluto-6753343.php

The 'snail' is consistent in form with ejecta from a lava tube. Very strange.

Jerry
2016-Jan-28, 03:27 AM
https://ac.arc.nasa.gov/p63rs4p8sf1/?launcher=false&fcsContent=true&pbMode=normal

This is about a forty-five minute presentation; and I wish he would have had two to three times that.

Some high points: There is not water signature in the white 'Heart' region of Pluto, but there is water in the mountain and red areas.

The dark areas are very red.

The white colored strata in the north polar region, and on the mountain peaks, is spectrometrically determined to contain methane ice.

The white heart region is likely frozen nitrogen and has no signature of water-ice. There is evidence that it is geologically very young, and goes through a process of inversion; melting and rising from the bottom and refreezing. The Heart region is likely an impact basin that is not very deep.

There are nitrogen 'frozen lakes' within the mountains. Since water ice is lighter than most forms of nitrogen ice, it is thought that the mountains may be 'floating on nitrogen; (although this is somewhat at odds with the hypothesis that the heart is a shallow impact basin).

The atmosphere is perplexingly less extended than predicted by models. (This is also true of Titan.)

The red regions, in Stern's words, are "hypothesized to be tholins".

Jerry
2016-Jan-31, 09:54 AM
http://www.nasa.gov/image-feature/pluto-s-widespread-water-ice