Green Baron

Ah ! Now i see ... no, i didn't get that, again, sorry. Adam & Eve dressed in maple leafs in paradise ? That is early/high medieval thoughts :-)

Ok, sorry for that. I thought it was one of your usual jokes ;-) Clothing is available to humans at least since 200.000 years. "Why ?" Nobody has no idea. Curiosity ?

You judge from the viewpoint of a sedentary organism. Approach it from the other side: the lifestyle is not nomadic (nomadic lifestyle emerged in the neolithic) and it is not forced. Groups moving are not as exposed to the "whims of the environment" as sedentary ones. The do not depend that much because they adapt their behaviour quickly. It is a good solution for the given situation, the niche of humans, and it worked well for 100.000s of years. Which was far more sustainable than what we do now. It'll not last that long ;-) Sure they did. As do people today who hunt on foot or work with working animals, like dogs for the blind or work horses in the woods.

lol. well, i didn't have a gender specific plan of life in mind, there are ladies who live the same way, but of course, in a certain way, that is how one can see it. How about "an individualist's cave", or "my home is my castle". Apart from the "social" aspect, the own house is also financially a declaration of independence. Apart from the bubble that popped in the US in the early 2000s, real estate values have always been stable or even climbing. Which is no guarantee for the future of course. But if you expect a higher inflation rate for the years to come, do it now. But only with a good part of own money.

True, only these people weren't hungry/starving. Especially those living in late ice age can be regarded as having lived in a rich environment, where they waited for the herd's wanderings at narrows or river crossings or simply on a hill in the plain looking out. What's on the menu today ? Sure, they had to gather, run, kill, prepare, transport (or transport, prepare :-)), dig or pick for the side dish, cook and sit together, and then there was enough for a few days. It probably was ... convenient. I can imagine (just a random thought) that this was more convenient, rewarding, social than it is for some of us today.

A bit late, but: 1907

Hehe, sure, i'd call you as well. But that'll take weeks to explain and needed access to German and French literature. Just believe me, paleolithic art was not done by pubescent boys and girls, the idea alone caused us to laugh out loud back then. It is not at me, Guthrie has no evidence for this claim and wild guessing (who cites him at all in publications ?), but we can draw analogies to for example shamanism or rites of hunting, rather the contrary. I know no good book in English, i am sorry, simply because there is nothing comparable art as in France and southern Germany anywhere in the English speaking world. Maybe you can find good English publications on the matter by Nicolas Conard. But that would probably not be for the broad public ... Take a look at Grotte Chauvet, Lascaux, the figurines of the Swabian Alb, music instruments, atlatls (propulseurs) from France ... Anyone who has worked with the material can tell this was not made by children. The idea is absurd. Edit, texts from people i would consider serious on the matter: http://www.bradshawfoundation.com/clottes/meanings.php

Because people don't understand the difference between an element, a mineral and a rock, and an asteroid and a planet like earth. Why is it so difficult to grasp that an asteroid is not earth with its dynamics ? Yes. That is the classic most fundamental address to a piece of stone on earth. In many cases it can be done on site with very basic equipment. Because we have abundant examples and rocks here are the outcome of geological processes, of the dynamics of the earth from the core to the edge of space. Rocks are composed of minerals, in many different forms (there are thousands), and minerals are composed of chemical elements. Rocks are the outcome of tectonic processes, weathering, transport, etc. You will find the same elements on celestial bodies as on earth, and in many cases the same minerals (though by far not in that variety as on earth), but you will not find the same rocks there because the processes that form them do not exist. Why is that so difficult to grasp i ask myself ? Of course, you are allowed to use whatever designation you want, but you will not find a classification of rocks for asteroids that resembles the classification on earth because these rocks do not exist there. Some of them or similar ones may exist on other planets, as on outcome of the processes that are at work there. But there are no sediments on an asteroid because there is no weathering and transport as on earth. There is no metamorphosis because no hot magma climbs from a core boundary, and no subduction brings surface material into a GPa and 2.000K regime. But there is a classification for roids. Use it. Or leave it. I don't care (any more).

Oh, am i that confused ? :-) I want to make a renderer for all kinds of celestial bodies that somehow are an ellipsoid. I extract the ellipsoids from a unit sphere by tessellation and clad it in one or two prefabricated textures for the overview from afar. I want to display surface details by extracting position posts away from center with the help of a displacement map, a single channel texture whose values represent a height relative to the ellipsoid. Heightmap data can come from many sources, downloaded real world data, generated maps from simulation of natural processes, or from a typical noise generator, like perlin. Display of surface details, because it is a lot of data, needs a level of detail (lod) algorithm to reduce complexity and control detail levels depending on distance from the viewer, and a means to portion the data in units that can easily and seamlessly be loaded into memory. A single channel 16bit displacement for the whole earth with posts every 90m (srtm-data) would have many 10s of GB ... The github-rep contains my first try on a render framework for this, with examples for the ellipsoid tessellation and a basic version of a displacement map. I am now working on the lod thing and a related data structure.

It is (probably like almost anything else) bread in Supernovae and flies through space. It does not appear in all of those m. and i. rocks, in fact its origin has little to do with these processes, as much as for example a feldspar. It exists independently of the process, just accept it, though it and its modifications are abundant on earth and in space. After all, it is Iron/Magnesium and Silicon dioxide. You have probably stepped on it today several times, in more or less high concentrations.

Dale Guthrie is a nut. He sat in a backwater institution in Alaska working on frozen mammoths. His naive and somewhat pubertal "opinions" about paleolithic art have no significance in prehistory. Without hurting anybodies feelings, the book is a bad and grossly misleading introduction into paleolithic art and its possible significance. Paleolithic art, especially that of the European Upper Paleolithic, has been discussed and is discussed, unfortunately many good texts are in French and German, i know only very few English speaking people working on it and they work on detail questions and when they find something they feel they must share they publish it in journals. Paleolithic art is so fascinating, it actually played a huge role in my decision to study stone age. Diet and paleo: as a former prehistorian, i repeat: people have eaten many things throughout the times and spaces, from dug out roots to megafauna. Folks in the continental ice age did have a high meat part, but also ate herbs, nuts, fish or seafood if they had the opportunity. Others living at the cost also ate seafood in a higher concentration and variety, while some gatherer groups concentrated more on berries and roots. This really depends on the conditions and there is no generalization, not "this is superior than that". We have enough find places and analyses to tell this. To insinuate there is only one way or put a lifestyle of certain groups over that of others is misleading, a little like "i am the guru, follow me !". I find that educated people do not need that. If i may give a tip: eat fresh, veggies, fruit, a piece of meat from time to time if you like, avoid industrial food, go to the farmer's market, cook at home; if you have a sickness and need help then do not seek help and fall for those omnipresent gurus that try to catch your attention. If medicine can't help (that happens) then there might eventually be no help or not yet. After all, the treatment of rare cases does not generate much money and so institutions might have not much of an interest to do research. It is a sad reality, but people actually die from sicknesses that cannot be treated.

It goes deeper (haha): the concept of metamorphic (m.) minerals is a bit misleading. A schist is metamorphic, a gneiss, a marble may be (contact metamorphosis). These rocks are composed of minerals, but most of these minerals can exist elsewhere. Some minerals otoh can be transformed through (regional) metamorphosis and form new minerals, even as indicators. But an indicator of a pressure of 60km depth on earth and 900° would be impossible to find on an asteroid (gravity is missing, one does not have that combination). For metamorphosis to take place one needs rocks to be transformed, like an intrusion of a pluton into a package of sediments, or subduction of an ocean plate with sediments on top. Plate tectonics play the main role here. M. in its various forms is in itself not an origin, but part of a process. The oldest rocks on earth are m., the original rocks are gone. This is where the process and the state must not be confused, or these misunderstandings happen. Almost. Peridot ;-) I do. Olivine is a natural silicate mineral with Mg, Fe, Mn, some configurations are stable, others will weather away more quickly when exposed to surface conditions on earth. Olivine has pressure modifications typical for earth's upper mantel(*). But it also occurs freely, in cometary dust, etc. Astronomical style processes that father it aren't all that difficult to imagine ;-) (*) Wikipedia has an article on Fosterite that may serve as a further reading.

Not that easy to find something without an obvious political fore- or background. (a soccer team apparently)

Oh yes, it is. I did this relatively early in life and it was the step towards independence. Much more like the first refridgerator, the first car, partner, ... Since then, each time when i moved, i made a little plus when i sold the old house and bought a new one in the place where i moved to. Fridges, cars, girls came and went, but now i always have that space where i can retreat and do what i want without bothering anyone or being bothered by the ones over my head. Very satisfying :-)

I repeat, olivine is not a metamorphic mineral, and yes, it appears on its own, even in crystalline gem form; or on the moon, and was found in asteroid samples (Itokawa). Wikipedia says this not all that wrong: "Other minerals, such as olivines, pyroxenes, amphiboles, micas, feldspars, and quartz, may be found in metamorphic rocks, but are not necessarily the result of the process of metamorphism."

Sorry, this is becoming childish nitpicking. You do not understand. Olivine is not a metamorphic mineral, but may be the result of igneous crystallisation. It is also a main component of earth's upper mantle and in silicate asteroids. Read the wikipedia link you posted, it is not that bad as i can tell from a short overfly. And stop bothering me with nitpicking. ------------- The question was how do we classify Ryugu rocks geologically. Geology as on earth does not apply. We give it a spectral classification based on surface properties. This and orbital parameters leads us to an estimation of the main "ingredients". Which, in analogy with meteorites found on earth, leads us to a proposed mineral composition. More when we have moar data.

You tell me. How did the ice form ? How long is it there ? Are there processes that change its composition, its forming ? Any dynamics like thawing and new buildup ? Transport ? Atmosphere ? Weathering ? What is the ground like ? Is the chemism changing ? How does it affect or alter the ground ? Is Ceres covered with the products of something ? -------------- Olivine is a mineral. Metamorphosis is a process. I could say this 3 times :-)

Nonsense. Where did i say that ?

It is like asking "at what distance from the beach do we switch from car to ship classification ?". We don't because the distance is irrelevant, as is the size. The classification of rocks on earth is tied to the dynamic processes that form them, to physics (gravity, chemistry, heat, pressure, elements, ...), not to the size of a celestial object. But the size does influence the processes because a small object has other dynamics (if at all) as a big one. But there is no generalization. "It is here like this, so it must be there the same" does not work because "there" is different(*). And MANY other processes one can find on earth, partly early Mars, but NOT on Ryugu. When we find a mineral that apparently has undergone similar processes as we observe on earth we can use similar expressions to describe them. Until then we live with the classifications we have and do not mic apples and eggs (tastes awful, maybe with sugar and cream ?). If you need simple terms then here you go: Rocky asteroids are made from material similar to earths mantle (olivine, pyroxene, ..). Metallic 'roids are made from material similar to earth's core: iron, nickel. Mixed pickle. Comets (and KBOs) are rather dirty snowballs, with a lot of other stuff like hydrogen, oxygen, carbon, nitrogen, ... Some 'roids have a cover of these volatiles plus carbon, aka organics (and maybe other elements). The spectral classification gives more in- and onsight. You will not find a sandstone on Ryugu. You will not find a carbonate platform on Mars. There is no braided river on Pluto. No continental shelf with a mud cover does exist on Titan. No asteroid or dwarf planet shows the processes that form sediments as those on earth. That is why this classification does not apply. Until we find evidence for plate tectonics, orogenies, rivers, glaciers, atmospheres, etc. pp. These things are in discussion and will be more so as new data comes in. Until then, live with the classifications we have. (*)Edit: i must say though that according to a certain principle ("Uniformitarianism", handle with care !) we can assume that the similar conditions will likely produce similar results just because physics are assumed to be the same on earth than on other bodies. That is how we judge the valleys on Mars. But conditions ARE NOT the same elsewhere, so this principle should only be used by experts and with as little guessing as possible :-)

We have a classification for asteroids, based on their spectra. Let us use it until there is new data. I mean, nobody has the idea of using terms like convertible, suv, semitruck, station wagon for ships on the ocean :-)

SGAI ? SGAS ? Where can i find what this is about ?

Planetesimals are much too small for differentiation. Something the size of Vesta is needed for it to start (gravitationally). "Protoplanets" are not official and you may have a different opinion than i, so let's say "dwarf planets". We are talking different things: "transport" of sediments means glaciers and ice shields, ice shelves on oceans, not small snowballs or "graupel". These latter are stable over billions of years, there is no such transport. "Regolith" may be a better word for this, than "sediments". It is not mine. Dwarf planets, comets, planets. I think you can answer the question yourself. Features on Mars may be a hint that in its early years there were sedimentary processes similar to those on earth (flowing water, thick atmosphere). No such things (fluviatile valleys and incises, thick sheeted silicate layers, ...) exist on objects like Ryugu. There may of course be a gray or transition zone somewhere above Vesta size objects that can "afford" an atmosphere and some evolution processes, flowing water and certain forms of circulations between the spheres. Future will show ;-)

That is hypothetical. What is a protoplanet ? Is it already differentiated ? Where does the piece come from ? Has it undergone changes from the original material, how long was it exposed, has it undergone other changes in the meantime (high pressure modifications have a limited stability, if pressure is released). The question works better the other way round: if a piece is found (example: meteorites from Mars), we can tell with some confidence that it was a basalt, it formed under that temperature and that pressure (facies) and has traveled around for quite some time. So we know from what depth on Mars it came from. Besides weathering processes, means, medium and distance of transport are the very base of sediment definition and classification. Grain size, chemistry, minerals largely depend on that. If it is preserved well, one can tell where it came from, how it was transported and the regime it was deposited in. Did it flow, was it blown, was it transported by ice ? Constantly or periodically ? How far was it transported ? How high was the energy ? Was it cold or warm ? Which minerals weathered out ? etc. pp. I must add: sediment geology is complicated. I mean complicated. :-) And there many different subjects with different view points for a given case, like oil industry, paleontology, construction works, they all have different questions. But none are adoptable to asteroids, comets and the likes. It would be best to avoid these concepts when speaking about small celestial objects. Edit: Back to Ryugu: once the samples are back on earth i am sure we "will have some very nice data here" to analyse.

Ok, i am doing this for the first time, have patience if something (or everything) is messed up. Here is the first take, the base of what i would like to be just one more of those render frameworks for things ellipsoid. I don't guarantee no progress or anything else. Please read the readme.md, especially the credits. It is naive, wanting, buggy, and i ask myself if it is worth showing. But I will be happy about all kind of comments :-) github More inline doc as soon as the frequency of changes settles ... (Hint: normal shading in SimpleHeightMap isn't implemented yet, but everything else is. And there are readmes with links to texture downloads.) Next step: lod