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SpaceEngine Planet Classifications
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| SpaceEngineer | Date: Wednesday, 28.12.2011, 11:35 | Message # 31 |
 Author of Space Engine
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Russian Federation
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| Hi Chris, thanks for the detailed answer.
Quote (Chris) But if your purpose for scanning the universe is to look for habitable planets then 3 temperature classes should be enough. That would be, "Too Hot" - "Habitable" - "Too Cold".
I want to subdivide hot planets to really hot - like hot jupiters with effective temperature > 800 K, and not very hot, but still warm, like Mercury or Venus. Warm planets can support some extremophilic life, while on hot planets even metals are melted. In a similiar way, I want to subdivide cold planets into two categories. First - less cooler, below water freeze line, but under ammonia or methane freeze line; some exotic ammonia life can exist on these planets. Second - very cold planets where even ammonia or methane freezes. So, we get 5 classes:
Hot - Warm - Temperate - Cold - Very cold.
But I dislike "Very cold" - as it uses two words. I don't know which word is suitable in English, maybe "Cryogenic" is better than "Frozen"?
Next, I subdivide temperate class into 3 subcategories - more warm and more cool than Earth. Liquid water can exist on surface of planets of all these subcategories, and category name gives information of its major state. I.e. temperate terra has much liquid water; a more warm temperate terra has huge arud areas, a more cool temperate terra has huge glaciers, but a "more warm temperate" and a "more cool temperate" is too long, so I'll name it as "calid" and "cool". In Russian language, we have good distinction between word pairs "cool"-"cold" and "warm"-"calid"; I could not find good pairs in English. Of course, I can just remove this little subdivision and call it all "Temperate".
Quote (Chris) The planetary class called "Frozen Selena", is that class called "Frozen" just to sound colder than "Cold", or is it actually frozen? Meaning covered by an icy crust , and would that mean that a "cold icy selena" isn't actually frozen and infact icy. I guess not.
Next, about the structure classes. I divide planets by classes based on their interior composition and surface state (not clear classification, I agree).
Gas giant - composed by 80-100% of hydrogen and helium.
Ice giant - composed by 80-90% of water and ammonia ices, with 10-20% of hydrogen-helium atmosphere.
Oceania - composed by 50-80% of water, with relatively small iron-rock core.
Ice world - the same as Oceania, but with frozen ice crust.
Terra - big rocky body with iron core and relatively small amount of water: it should have seas and land masses together.
Desert - the same as Terra, but without water.
Selena - the same as Desert, but without atmosphere.
"Ice world" can be subdivided on "Titan" (Ice world with atmosphere and probably liquid hydrocarbons on surface) and some called "Icy" (icy an analog of Selena - it is almost all big satellites of Jupiter, Saturn, Uranus and Neptune). I don't like "Icy" - it is not a noun and is not a good translation to Russian.
So, moving away from this classification, I can suggest this one:
Gas giant (or Giant) - greater than 100 Earth's mass
Ice giant (or Subgiant) - between 10 and 100 Earth's mass
Superterra - between 3.0 and 10.0 Earth's mass
Terra - between 0.5 and 3.0 Earth's mass
Subterra - between 0.01 and 0.5 Earth's mass
Selena (or Dwarf) - between 0.0001 and 0.01 Earth's mass
Asteroid - lower than 0.0001 Earth's mass
But the subdivision is based not only on mass, but on relative amount of various materials too (this info wll be generated by new planetary system generator). I.e. if Superterra has 15% of its mass in form of hydrogen-helium atmosphere, it becomes an Ice giant. This classification doesn't show composition of a planet, I.e. Titan and Mars will be called "Subterra", despite the huge difference in their nature. Venus and Earth will be called "Terra" too... I like to have a separate class called "Terra" for Earth-like planets, almost Earth's twins.
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| DevonX | Date: Wednesday, 28.12.2011, 12:05 | Message # 32 |
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| Quote (SpaceEngineer) Superterra - between 3.0 and 10.0 Earth's mass
Terra - between 0.5 and 3.0 Earth's mass
Subterra - between 0.01 and 0.5 Earth's mass
I like this idea allot. This makes it faster to find the planet you are looking for. But this should only be applied to planes that is already classified as terras, as a sub genre. (current classification)
Edited by DevonX - Wednesday, 28.12.2011, 12:08 |
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| curiousepic | Date: Wednesday, 28.12.2011, 14:54 | Message # 33 |
 Space Pilot
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| I do like splitting terras into sub- and super-. But is there a programming reason you don't want two-word descriptors, like "very hot" and "arid terra"? I think many of us prefer this to using obscure words like "calid". I like "arid terra" for desert and "oceanic terra" for oceania.
When talking about whether a world is frozen or not - it would depend on the composition, right? Worlds with different atmospheres will have a frozen surface at different temperatures. So it might be best to not use "icy" and "frozen"; another reason to shift the scale and use "very cold". Also "cold/very cold oceanic terra" instead of "ice world" or "titan/titanian".
But again, do you not anticipate that changing the planet formation simulation will necessitate changing the classifications?
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Edited by curiousepic - Wednesday, 28.12.2011, 15:14 |
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| SpaceEngineer | Date: Wednesday, 28.12.2011, 18:20 | Message # 34 |
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Author of Space Engine
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| Quote (curiousepic) But again, do you not anticipate that changing the planet formation simulation will necessitate changing the classifications?
Classification is needed for surface texture generation system. For now it has 6 different types:
star
gas giant clouds layer
terrestrial clouds layes
terra surface (terra, desert, oceania)
selena surface (selena, ice world)
asteroid
Combining them into one will make the shader too huge - it won't compile on some computers.
Quote (curiousepic) I do like splitting terras into sub- and super-. But is there a programming reason you don't want two-word descriptors, like "very hot" and "arid terra"? I think many of us prefer this to using obscure words like "calid". I like "arid terra" for desert and "oceanic terra" for oceania.
I simply dislike descriptions that are too long. It will be much better if any word in the description made special sense, for example "warm desert": "warm" is the temperature class, "desert" is the surface class. If we add double-word classnames, it will look like "very warm arid terra": "very warm" is the temperature class, "arid terra" is the surface class...
BTW, Mars is a desert, but not arid, because it has a lot of water in the form of ice. How do you suggest to name this planet?
Quote (curiousepic) Also "cold/very cold oceanic terra" instead of "ice world" or "titan/titanian".
I dislike that too. Naming of icy moon "cold oceanic terra" is wierd...
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| Talisman | Date: Wednesday, 28.12.2011, 19:25 | Message # 35 |
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| Quote (SpaceEngineer) Gas giant (or Giant) - greater than 100 Earth's mass
Ice giant (or Subgiant) - between 10 and 100 Earth's mass
Superterra - between 3.0 and 10.0 Earth's mass
Terra - between 0.5 and 3.0 Earth's mass
Subterra - between 0.01 and 0.5 Earth's mass
Selena (or Dwarf) - between 0.0001 and 0.01 Earth's mass
Asteroid - lower than 0.0001 Earth's mass
Yes, I like this. And I think temperature classifications are fine. The more the better in my opinion.
Also, Frozen would be much better then cryogenic.
Also, I like the terra classifications, perhaps also have one for terra's (or desert) planets that have frozen over, some planets may be in a sort of ice age, where life is still suitable, they could be called "Ice Terra" or "Winter Terra" or Arctic, Boreal, or Glacial Terra.
I think there should be many more different planet classifications. 
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| SpaceEngineer | Date: Wednesday, 28.12.2011, 20:12 | Message # 36 |
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Author of Space Engine
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Russian Federation
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| Quote (Talisman) Also, I like the terra classifications, perhaps also have one for terra's (or desert) planets that have frozen over, some planets may be in a sort of ice age, where life is still suitable, they could be called "Ice Terra" or "Winter Terra" or Arctic, Boreal, or Glacial Terra.
So, Mars should be called "Cool arid glacial subterra": it's cool, and has no huge amount of water, all the water is frozen (and enveloped with dust), and it's a small terrestrial planet.
Earth is a "Temperate normal (?) terra"
Venus is a "Warm arid desert"
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| DevonX | Date: Wednesday, 28.12.2011, 21:47 | Message # 37 |
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Space Pilot
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Norway
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| Quote (SpaceEngineer) Earth is "Temperate normal (?) terra" |
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| SpaceEngineer | Date: Wednesday, 28.12.2011, 22:56 | Message # 38 |
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Author of Space Engine
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Russian Federation
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| Quote (DevonX) Earth is "Temperate normal (?) terra"
Temperate habitable terra. I like the other names too ^^
How to name non-arid, non-wet, non-glacier, non-water, non-habitable, and all other "non" terras? "Normal" is bad a class name.
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| DevonX | Date: Wednesday, 28.12.2011, 23:59 | Message # 39 |
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Space Pilot
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| non-arid: floressent or something like that, non-wet not shure what you are meaning by that. non-glacier: need to think about this one, non-water: dry ?, inhabitable terra. I think its just to find the right names on the non terras 
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| HarbingerDawn | Date: Thursday, 29.12.2011, 12:26 | Message # 40 |
 Cosmic Curator
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| Quote (SpaceEngineer) How to name non-arid, non-wet, non-glacier, non-water, non-habitable, and all other "non" terras?
What would such a world be like? If it's not arid, then must it not be glacial/wet/water?
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| gpaw5765 | Date: Thursday, 29.12.2011, 13:52 | Message # 41 |
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| I think a good way to classify planets could be by using three attributes (Temperature, Composition and Size) and using one descriptor for each attribute:
Temperature:
Hot
Warm
Calid
Temperate
Cool
Cold
Very Cold
Composition:
Gas
Ice
Methane/Hydrocarbonic
Oceanic/Water
Oxygen/Fertile/Rocky/Wet
Iron
Desert/Barren/Arid
Size:
Giant
Subgiant
Superterra
Terra
Subterra
Selena
Asteroid
Using this system any planet and moon could be classified easyly, although more descriptors may need to be added for the "Composition" attribute. I particularly don't like the descriptors I've put for the Earth's composition, but I coudn't think of anything better. Of course some combinations would be impossible: for example a Gas Subterra cannot exist because the planet's gravity couldn't hold the atmosphere, etc.
In this classification, the main bodies of the solar system would be more or less like this:
Mecury: Hot Iron Subterra
Venus: Hot Iron Terra
Earth: Temperate Fertile Terra
Moon: Cold Desert Selena
Mars: Cool Desert Subterra
Jupiter: Cold Gas Giant
Saturn: Cold Gas Subgiant
Titan: Cold Hydrocarbonic Subterra
Uranus/Neptune: Very Cold Ice Subgiant
This system for planet classification has the advantage of being more flexible than having a small group of predefined planet types.
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| DevonX | Date: Thursday, 29.12.2011, 14:22 | Message # 42 |
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Space Pilot
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| Quote (gpaw5765) I think a good way to classify planets could be by using three attributes (Temperature, Composition and Size) and using one descriptor for each attribute:
But this dont cover if the planet is habitable or not.
Quote (gpaw5765) Size:
Giant
Subgiant
Superterra
Terra
Subterra
Selena
Asteroid
I dont think you should use terra as a size parameter as the word terra defines the composition of the planet.
Edited by DevonX - Thursday, 29.12.2011, 14:33 |
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| Chris | Date: Thursday, 29.12.2011, 16:53 | Message # 43 |
 Space Tourist
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| This planetary formation simulation is the feature i'm looking the most forward to seeing.
Along with the classification of planets you decide to use, you could add a single number to the terrestrial planets, to easily decribe the earth similarity.
I definately think the (ESI) would be useful for that purpose.
Once the more important work is done, and you start working on UI.
I think a good tool for the user would be to let them set their own weight exponents for the various properties of a planet.
The end result would be read as a single number like the Earth Similarity Index, tailormade for just the search the user has in mind.
Funny how interesting this cassification discussion is.
Temperature.
Hot, More than 127C. No chance of life.
Warm, 27C to 127C. Class for extremophiles.
Temperate, -23C to 27C. Habitable for man.
Cold, -73C to -23C. Class for extremopiles.
Very Cold, Less than -73C. No chance of life.
Class.Mass. Atmo. Composition. Surface Water.
Asterioid. Mass. Less than 0.0001. No Atmo. Composition. Silicate, Iron. Less than 50% Ice.
-Icy(Comet). Composition. Silicate, Iron. More than 50% Ice.
Selena. Mass. 0.0001 to 0.01. No Atmo. Composition. Silicate, Iron. Less than 50% Ice.
-Icy. Composition. Silicate, Iron. More than 50% Ice.
Subterra. Mass 0.01 to 0.5. Atmo. Composition. Silicate, Iron or Ice. Surface Water. 10% to 50% Water.
Terra. Mass 0.5 to 3. Atmo. Composition. Silicate, Iron or Ice. Surface Water. 10% to 50% Water.
Superterra. Mass 3 to 10. Composition. Atmo. Silicate, Iron or Ice. Surface Water. 10% to 50% Water.
Icy. Surface Water. More than 50% Ice.
Arid. Surface Water. Less than 10% Water.
Oceanic. Surface Water. More than 50% Water.
Ice Subgiant. Mass. 10 to 100. Atmo. Composition. More than 80% Water, Ammonia.
Gas Giant. Mass. More than 100. Atmo. Composition. More than 80% Hydrogen, Helium.
Class Terra = Atmo
Subclasses Icy, Arid and Oceanic are related to surface water availability, not interior compositon. Life or habitability is the objective.
Class Selena = No Atmo
Subclass Icy, related to interior compositon for Asteroid and Selena classes.
Using the above..
Mercury. Hot Arid Subterra.
Venus. Hot Arid Terra.
Earth's Twin. Temperate Terra with Life.
Mars. Cold Arid Subterra. Water may be present but not in liquid state.
Europa. Very Cold Icy Selena. Posibly an Oceanic microterra, certainly covered by an ice crust.
Titan. Very Cold Subterra. Pools of liquids present, not water.
Quote But the subdivision is based not only on mass, but on relative amount of various materials too (this info wll be generated by new planetary system generator). I.e. if Superterra has 15% of its mass in form of hydrogen-helium atmosphere, it becomes an Ice giant. This classification doesn't show composition of a planet, I.e. Titan and Mars will be called "Subterra", despite the huge difference in their nature. Venus and Earth will be called "Terra" too... I like to have a separate class called "Terra" for Earth-like planets, almost Earth's twins.
I'd separate Selenas from Subterras at the point where the mass is too low to retain a breathable atmosphere for man.
That way terra does become very common, if you want to reserve them for earth's twin's i understand.
But on the other hand terrestrial does mean solid bodies as opposed to gasseous bodies like Gas giants.
A way to go around the problem could be to create two classes Terrestrial and Gasseous, related to interior composition only, not mass.
Then put in the other classes we have above, accordingly.
Terrestrial
-Asteroid
-Selena
-Subterra
-Terra
-Superterra
Gasseous
-Subgiant
-Giant
I have no better idea how to separate Venus and Earth than to do it with a (ESI) or make the user read the detailed data window.
Can't think of a fitting class name or system.
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| gpaw5765 | Date: Thursday, 29.12.2011, 17:59 | Message # 44 |
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Astronaut
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| Quote (DevonX) But this dont cover if the planet is habitable or not.
Wether the planet is habitable or not would depend on all 3 attributes being suitable for (human) life. The requirements would be:
Temperature: Calid, Temperate or Warm
Size: Subterra, Terra or Superterra
Composition: ? (not sure about this one, probably SpaceEngineer knows better the kind of composition we are likely to find on planets, and which ones would be suitable for life.
Quote (DevonX) I dont think you should use terra as a size parameter as the word terra defines the composition of the planet.
I'm using it to describe the size of the planet and not the composition. I think this is the way it is commonly used in astronomy when referring to extrasolar planets, as there's no information whatsoever on the composition of those planets.
Quote (Chris) But on the other hand terrestrial does mean solid bodies as opposed to gasseous bodies like Gas giants. A way to go around the problem could be to create two classes Terrestrial and Gasseous, related to interior composition only, not mass.
I don't think that's necessary, as Gasseous planets are impossible in planets as "small" as a Superterra (not enough gravity to hold the gas). Only possible Gasseous planets are Gas Giant and Gas Subgiant.
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| DevonX | Date: Thursday, 29.12.2011, 19:02 | Message # 45 |
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Space Pilot
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| Quote (gpaw5765) Wether the planet is habitable or not would depend on all 3 attributes being suitable for (human) life.......
I still don't think its necessary to classify the planet on size more than the radius is already doing.
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