Chlorophyliac humans, binary stars and boiling oceans

[gestaltist]

I am tinkering with a somewhat unusual conworld, and I would like to share some of my ideas, and hopefully receive some ideas back. It arose from my curiosity around the possible fate of a planet orbiting a binary star. It evolved into something like this:

The planet in question orbits a binary star, and is significantly hotter than the Earth (being exposed to the radiation from two suns). I am imagining a planet with temperatures around the equator being about 100C/212F (a boiling ocean - such a cool picture), and the climate in the polar circle being moderate. Do you guys think this is at least marginally feasible? I am wondering if climate in the polar circle could ever be temperate (given the day-night variability). Also: what effect would the ultra-high evaporation around the equator have on the rest of the planet?

The second idea is really outlandish, but fun: I am imagining a situation where one of the stars begins to emit some kind of unknown energy at one point. This leads to some animals developing a blue/purple skin pigment with a similar role as the chlorophyll, i.e., they can get a huge chunk of their nutrients from exposure to radiation of this star. I know this is rather improbable or even downright impossible. But it is fun. I imagine this happening at a relatively late stage of evolution, so there is an alternate race of humanoids which have this wonderful skin pigment, but are otherwise almost identical with humans. Let’s call them the Purples.

Possible features of the civilization of the Purples:
- they would avoid heavily forested areas, areas with high cloudiness and the higher latitudes - all of them would mean too little benefit from the sun - and would subsequently be claimed by „normal“ humans.
- they would go naked or use transparent clothing, would strongly dislike armor
- they would rarely eat (once every 2-3 days?) if getting enough sun
- fasting would mean wearing clothes
- due to low food consumption, the population density would be higher than in human societies
- architecture: their housing would be rather simplistic but they would develop wonderfully elaborate gardens to spend time in (to maximize sun exposure)
- they would prefer activities and professions that don’t require being indoors: farming, horseback riding, sailing, trading; also philosophy and scientific speculation
- they would suck at typically indoors activities such as mining or crafting - which would be the specialty of normal humans.
- as a result of the above, they would be very quick to adopt agriculture, and would be very expansive due to high population, but they would be slower to develop technologies revolving around fossil fuels, metals and such
- this could lead to productive coexistence with the humans due to overarching specialties, or could lead to bloody conflicts, where the Purples’ high numbers and superior organization would be offset by the humans’ superior weapons and armor
- the Purples would probably strongly worship the suns and see humans as „creatures of the shadow"

What do you guys think?

[Zaarin]

The planet in question orbits a binary star

There are three ways a planet can be involved in a binary star system: a figure-eight orbit around both stars, which is unstable over long periods of time; orbit the common center of gravity of two very close stars, which leaves in doubt whether the planet would be habitable on account of intense radiation (though perhaps it could be shielded by being the moon of a hot Jupiter--if it can survive the hot Jupiter's radiation); or, most habitably, by orbiting one of two distant companion stars.

I am imagining a planet with temperatures around the equator being about 100C/212F (a boiling ocean - such a cool picture), and the climate in the polar circle being moderate.

I'm guessing from this that you're aiming for option two. Extreme temperatures notwithstanding, you'll need a way to protect the planet from the intense radiation if you want life (or water--or an atmosphere, for that matter) to exist on the planet. Orbiting a hot Jupiter is the best way I can think of. Perhaps someone with better knowledge of geology than I have could suggest a way to give the planet a crazy magnetosphere, but I'm not familiar with any.

Also: what effect would the ultra-high evaporation around the equator have on the rest of the planet?

I suspect it would cause a pretty intense greenhouse effect with such high concentrations of water vapor in the atmosphere. On the one hand, this will distribute heat around the planet; on the other hand, it could lead to a runaway greenhouse effect.

The second idea is really outlandish, but fun: I am imagining a situation where one of the stars begins to emit some kind of unknown energy at one point. This leads to some animals developing a blue/purple skin pigment with a similar role as the chlorophyll, i.e., they can get a huge chunk of their nutrients from exposure to radiation of this star. I know this is rather improbable or even downright impossible. But it is fun. I imagine this happening at a relatively late stage of evolution, so there is an alternate race of humanoids which have this wonderful skin pigment, but are otherwise almost identical with humans. Let’s call them the Purples.

The cause might be improbable, but I see no reason why one couldn't have something in between the dichotomy of plant vs. animal--a mobile plant/chlorophyllic animal. Such a creature would probably have quite a different structure than humans, though, since plants need to maximize surface area to absorb sunlight.

- they would avoid heavily forested areas, areas with high cloudiness and the higher latitudes - all of them would mean too little benefit from the sun - and would subsequently be claimed by „normal“ humans.

Based on what you said earlier, it sounds like your lower latitudes are going to be quite cloudy.

- architecture: their housing would be rather simplistic but they would develop wonderfully elaborate gardens to spend time in (to maximize sun exposure)
- they would prefer activities and professions that don’t require being indoors: farming, horseback riding, sailing, trading; also philosophy and scientific speculation

Would they really need buildings?

Just some input. Take it as you will.

[Pabappa]

I like the purple idea. Chlorophyll only won on Earth because green is the color that the sun emits very strongly but yet gets through to shallow water bottoms the best, which is where the first plants evidently grew up. And in the process it turned the entire plant kingdom green. So I dont know if a purple sort of alternate chlorophyll could arise that quickly without starting from tiny things and branching out a whole other kingdom. But the physics of it makes perfect sense. There are even a few primitive animals that have tiny plants basically living inside them, getting energy piped into their cells from the plants' chloroplasts just as naturally as if they were trees and their body was made of wood. So perhaps there is not a whole kingdom of purples, but just a group of animals that can grow plants in their skin and use the resulting nutrients without requiring a whole other kingdom of microorganisms to convert it into the nutrients they need.

Also I should add that stars are pretty stable; I wouldnt think the purple chlorophyll would need to arise only when one of the suns starts throwing a temper tantrum; it can happen just as randomly as the original chlorophyll did.

Not sure I understand the climate question. Are you saying the planet gets significantly more daytime than nighttime? I wouldnt think any temperatures would be out of reach; just make it make sense. If the oceans start bubbling away theyre either going to have to rain down really hard somewhere, to the point of needing to measure annual rainfall in miles, or else they will escape the atmosphere and the planet will dry out.

[Zaarin]

Not sure I understand the climate question. Are you saying the planet gets significantly more daytime than nighttime? I wouldnt think any temperatures would be out of reach; just make it make sense. If the oceans start bubbling away theyre either going to have to rain down really hard somewhere, to the point of needing to measure annual rainfall in miles, or else they will escape the atmosphere and the planet will dry out.

Presumably this will happen wherever the temperatures start to cool--at the terminus if we're talking about a day/night pattern or at the tropics otherwise. These locales would likely features permanent intense thunderstorms. Not sure what kind of implication that would have for life.

[gestaltist]

I am imagining a planet with temperatures around the equator being about 100C/212F (a boiling ocean - such a cool picture), and the climate in the polar circle being moderate.

I'm guessing from this that you're aiming for option two. Extreme temperatures notwithstanding, you'll need a way to protect the planet from the intense radiation if you want life (or water--or an atmosphere, for that matter) to exist on the planet. Orbiting a hot Jupiter is the best way I can think of. Perhaps someone with better knowledge of geology than I have could suggest a way to give the planet a crazy magnetosphere, but I'm not familiar with any.

Yes, I was thinking about option 2. I didn’t want to go the Jupiter route because of the wacky night-day cycle it would create. I was more interested in my purple humans than realism. To be honest, I am trying to find a way to logically explain the system as I imagined it. It might be impossible, though.

The cause might be improbable, but I see no reason why one couldn't have something in between the dichotomy of plant vs. animal--a mobile plant/chlorophyllic animal. Such a creature would probably have quite a different structure than humans, though, since plants need to maximize surface area to absorb sunlight.

Yeah, that’s why I wanted to have it late in the evolution process: more like an extra mutation that turned out well.

Based on what you said earlier, it sounds like your lower latitudes are going to be quite cloudy.

Not necessarily. Due to Hadley cells, the equatorial air doesn’t go beyond 30 degrees of latitude on Earth. (Which is why Sahara is so dry, to give an example). I don’t see why this wouldn’t work any different on this planet, so I suppose the low latitudes would be full of hot vapor, there would be an inhabitable super-hot desert at around 30 degrees, but there could be subtropical climate at European latitudes and moderate climate on the polar circle. At least so went my initial idea.

Would they really need buildings?

That’s a good question. I guess it depends on the local climate. Nights can get chilly, even in otherwise very hot areas.

Just some input. Take it as you will.

I take it with gratitude.

I like the purple idea. Chlorophyll only won on Earth because green is the color that the sun emits very strongly but yet gets through to shallow water bottoms the best, which is where the first plants evidently grew up. And in the process it turned the entire plant kingdom green. So I dont know if a purple sort of alternate chlorophyll could arise that quickly without starting from tiny things and branching out a whole other kingdom. But the physics of it makes perfect sense. There are even a few primitive animals that have tiny plants basically living inside them, getting energy piped into their cells from the plants' chloroplasts just as naturally as if they were trees and their body was made of wood. So perhaps there is not a whole kingdom of purples, but just a group of animals that can grow plants in their skin and use the resulting nutrients without requiring a whole other kingdom of microorganisms to convert it into the nutrients they need.

Also I should add that stars are pretty stable; I wouldnt think the purple chlorophyll would need to arise only when one of the suns starts throwing a temper tantrum; it can happen just as randomly as the original chlorophyll did.

I LOVE this. I would never have thought of such an explanation. It has the added benefit of allowing me to decouple my „purple people“ from my „binary star“ idea. And as Zaarin pointed out, binary stars pose several problems.

Not sure I understand the climate question. Are you saying the planet gets significantly more daytime than nighttime? I wouldnt think any temperatures would be out of reach; just make it make sense. If the oceans start bubbling away theyre either going to have to rain down really hard somewhere, to the point of needing to measure annual rainfall in miles, or else they will escape the atmosphere and the planet will dry out.

To explain my question: I wonder if the fact that days are very long in the summer and very short in the winter wouldn’t cause the climate in the polar circle to be radically different from, say, Europe, even if it had the same median temperature.

And yeah: the boiling ocean sounds very cool, but would probably be too unstable in real life.

[gestaltist]

Not sure I understand the climate question. Are you saying the planet gets significantly more daytime than nighttime? I wouldnt think any temperatures would be out of reach; just make it make sense. If the oceans start bubbling away theyre either going to have to rain down really hard somewhere, to the point of needing to measure annual rainfall in miles, or else they will escape the atmosphere and the planet will dry out.

Presumably this will happen wherever the temperatures start to cool--at the terminus if we're talking about a day/night pattern or at the tropics otherwise. These locales would likely features permanent intense thunderstorms. Not sure what kind of implication that would have for life.

That’s what I was thinking. Such a planet would have a zone that’s completely inhospitable between the tropics. The habitable zone would extend from 40 degrees to the poles, I think.

[vokzhen]

A the huge disclaimer that this is speculation on my part, I'd think a boiling ocean would cause a boiling planet. Water may not be as efficient as CO2, but it is still a greenhouse gas, and a huge amount of boiling water vapor at the equator would raise temperatures world-wide. The massive dieoff of vegetation around the equator would probably exacerbate the problem (EDIT: if it started more Earth-like). At a further guess, drought would be the norm, as the warmer temperatures overall would allow vastly more water vapor in the air before it was forced to precipitate out.

Also, just to be clear I think it would have to be a "special" and unknown kind of energy. A quick glance shows that solar cells have max out just under 50% efficiency, standard commercial solar cells are 12-16%, and plants have 3-6% efficiency. You'd need somewhere in the area of 25-30% efficiency to power a human. Though that's, of course, assuming a Sol-like solar output (but also assuming an Earth-like atmosphere, and I have a feeling your atmosphere is going to be a lot denser).

[Lambuzhao]

Atmospheric Pressure is also something worth considering.

The thicker the atmosphere, the higher the pressure. So a hotter hydrology (whether water, or some other liquid) would be more stable at higher pressure.

Taken the other way, Mars is quite chilly. But due to the atmospheric pressure being 1/100th that of earth, liquid water would sizzle and boil away at the near frigid surface (well, near-frigid for a good portion of the surface).

............................................................................................................................................................................................

Also, regarding purple chloroplasts - why the heck not? Another liquid that permits purple/ultraviolet wavelengths to admit to shallow depths, while reflecting/refracting other wavelengths, would be all you needed. I don't know of any such contenders, though.


And, looking at it another way, check out this article and its links-
http://www.huffingtonpost.com/2011/04/2 ... 51678.html

A similar one was published in Discover or Scientific American a year or two ago.
(this is NOT it, but close enough for now)
http://discovermagazine.com/2007/apr/space-plants

(Aha, paydirt, I think)
The cover illustration
http://www.mondolithic.com/wp-content/u ... Plants.jpg

This is the article, by Dr. Nancy Kiang from Scientific American
http://www.scientificamerican.com/artic ... er-worlds/

Now, as to how Chlorophyliac (or maybe Porphyrophiliac....they'd be possessed of porphyroplasts after all, not chloroplasts, right?) beings could evolve, I would think it would have been an early fusion (cf. mitochondria and chloroplast evolution from prokaryotes). Perhaps these beings are some kind of sentient fungi or
lichens

[gestaltist]

A the huge disclaimer that this is speculation on my part, I'd think a boiling ocean would cause a boiling planet.

Yeah, I think the boiling ocean idea has to be discarded, no matter how cool it sounds. Which leaves us with the question: what properties would a world have to have in order to have moderate climate in the polar circle?

Also, just to be clear I think it would have to be a "special" and unknown kind of energy. A quick glance shows that solar cells have max out just under 50% efficiency, standard commercial solar cells are 12-16%, and plants have 3-6% efficiency. You'd need somewhere in the area of 25-30% efficiency to power a human. Though that's, of course, assuming a Sol-like solar output (but also assuming an Earth-like atmosphere, and I have a feeling your atmosphere is going to be a lot denser).

And yet only a small percentage of a tree’s area is covered in chlorophyl, and is enough to power the tree.

The Purples would still need to eat, only less - so shooting for 12-15% efficiency would be enough, I think.

Atmospheric Pressure is also something worth considering.

Yeah, I am dropping the boiling ocean idea. Too many problems.

Also, regarding purple chloroplasts - why the heck not? Another liquid that permits purple/ultraviolet wavelengths to admit to shallow depths, while reflecting/refracting other wavelengths, would be all you needed. I don't know of any such contenders, though.

Which is OK. It is fantasy, I don’t want to be blatantly breaking any scientific laws, but I don’t care if it is only theoretically possible.

Also, thanks a lot for the articles: I have bookmarked them and will hopefully find the time to read them today.

Now, as to how Chlorophyliac (or maybe Porphyrophiliac....they'd be possessed of porphyroplasts after all, not chloroplasts, right?) beings could evolve, I would think it would have been an early fusion (cf. mitochondria and chloroplast evolution from prokaryotes). Perhaps these beings are some kind of sentient fungi or
lichens

„Porphyrophiliac“ makes me think of vampires because of „porphyric haemophilia“ in one of the Elder Scrolls games.

I don’t want sentient lichens - they are too far removed from humans. They would be cool in a sci-fi scenario where people discover a planet where such beings live, but I want a planet where humans coexist with the Purples, and they are very similar to them. I like Publipis’ idea where they are actually in symbiosis with some kind of plant/fungus/lichen that inhabits their skin. This makes it possible to have them very similar to humans (e.g., some kind of rare fungus „infects“ some proto-humans and this leads to a mutation and a symbiotic relationship while retaining „regular“ humans). It would also give me the liberty to only have select species with that trait (or maybe even only the Purples) without having to think about a whole new evolutionary tree.

[Zaarin]

Which leaves us with the question: what properties would a world have to have in order to have moderate climate in the polar circle?

An extreme axial tilt like Uranus'? Of course, that will warm up the poles but freeze the equator, so...

„Porphyrophiliac“ makes me think of vampires because of „porphyric haemophilia“ in one of the Elder Scrolls games.

Morrowind, the only Elder Scrolls game as far as I'm concerned.

[gestaltist]

Which leaves us with the question: what properties would a world have to have in order to have moderate climate in the polar circle?

An extreme axial tilt like Uranus'? Of course, that will warm up the poles but freeze the equator, so...

That would definitely be an option.

BTW, I found a thread over at CBB earlier (cannot find it now) that discussed bipolar stars. It turns out it is very feasible to have an Earth-like planet that orbits two dwarf stars, which in turn orbit a common barycenter, very close to one another. So the bipolar star might be back in business...

[Zaarin]

Which leaves us with the question: what properties would a world have to have in order to have moderate climate in the polar circle?

An extreme axial tilt like Uranus'? Of course, that will warm up the poles but freeze the equator, so...

That would definitely be an option.

BTW, I found a thread over at CBB earlier (cannot find it now) that discussed bipolar stars. It turns out it is very feasible to have an Earth-like planet that orbits two dwarf stars, which in turn orbit a common barycenter, very close to one another. So the bipolar star might be back in business...

Indeed, I assumed sunlike G/K stars.

[Arzena]

I was under the impression that Earth's polar areas were quite temperate several hundreds of millions of years ago. If my recollection is correct, then you wouldn't need a planet with a radical axial tilt to achieve a temperate Arctic/Antarctic zone.

[Fixsme]

Totally, planets orbiting twin stars have already been observed several times.

I have though a problem with the tilt of your planet. With that tilt, you would have a burning pole, a freezing pole and a temperate equator. The whole thing with a weird atmospheric circulation that tries to get the heat from the hot pole to the frozen one.

[gestaltist]

Totally, planets orbiting twin stars have already been observed several times.

I have though a problem with the tilt of your planet. With that tilt, you would have a burning pole, a freezing pole and a temperate equator. The whole thing with a weird atmospheric circulation that tries to get the heat from the hot pole to the frozen one.

But the tilt wasn’t even my idea. I was thinking along the lines of a tilt similar to that of the Earth.

[Salmoneus]

a) to make the poles temperate, you need to make the planet just like earth but very very slightly warmer. Honestly, this is such a trivial difference that there's no point even explaining it. Earth itself has normally had temperate poles; we just happen to be in the middle of an ice age at the moment.

b) no, extreme tilt doesn't mean one hot pole and one cold pole, because the axis does not point at the sun (unless it's also tidally locked). [What it means, broadly speaking, is that land at the poles has wild seasonal variation in temperatures, land at the tropics has a stable temperature but colder on average than the poles and the mid-latitudes, and water is warmer at the poles than the tropics]

c) apparently if you heat up a planet with a lot of water, you never actually get boiling oceans. Instead, you lose the ocean surface - you get a continuum between the sea and the atmosphere (which is so full of water vapour that there's no fixed line where it becomes a sea rather than a water-filled sky). Water worlds are apparently prone to becoming 'steam planets' in this way, because of runaway greenhouse effects. I don't know how land might interfere with this exactly, though.

[Lambuzhao]

„Porphyrophiliac“ makes me think of vampires because of „porphyric haemophilia“ in one of the Elder Scrolls games.

Morrowind, the only Elder Scrolls game as far as I'm concerned.

All gaming aside, looking a little deeper into porphyria-> Porphyrins, there are some interesting finds:

http://en.wikipedia.org/wiki/Porphyrin

Thus porphyrin macrocycles ... typically have very intense absorption bands in the visible region and may be deeply colored; the name "porphyrin" comes from the Greek word porphyros, meaning purple.

Porphyrins ... strongly absorb light, which is then converted to energy and heat in the illuminated areas.

http://en.wikipedia.org/wiki/Bacteriochlorophyll

http://en.wikipedia.org/wiki/Purple_bacteria

Purple bacteria may in fact be related to mitochondria...

...so it may not be a far stretch to have your Purples have an energy-reservoir organelle that functions like a chloroplast but is purple (due to porphyrin or bacteriochlorophyll or somesuch). A whole range of life-forms could have this organelle: archaea, algae, fungi, plants, animals.

[Lyhoko Leaci]

Humans are just too small and too active to have any sort of effective photosynthesis. (unless there's some sort of magic light or something that is 100 or so times brighter but only interacts with the chloroplasts and not much else to prevent overheating of the planet)

Photosynthetic cows: http://what-if.xkcd.com/17/

[Lambuzhao]

Human surface area is tricky, indeed.

Nonetheless, porphyrins can concentrate on shorter wavelength, higher energy electromagnetic waves (purple, ultraviolet... mebbe X ray?).

No doubt, getting sunburned is no fun, and that is due to predominantly ultraviolet radiation getting through a Terran style (thickness,composition) atmosphere.


Frankly, IMHO "purple" was a pretty spot-on choice.

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Oh yes, Porphyrins are from a mainly Terran environment (!). Bacteriochlorophyll works more efficiently with a sulfur-rich, oxygen poor environment.
But, they could definitely work in an environment with the parameters Sal proposed, a slightly hotter Earth-like world.


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Nonetheless, if the atmosphere of the planet in question were very thick for some reason, maybe plastids that absorbed lower frequency (red, infrared) radiation would be more beneficial. Enter phycoerytherin -

http://en.wikipedia.org/wiki/Chloroplast

the phycobilin phycoerytherin is responsible for giving many red algae their distinctive red color.[23] However, since they also contain the blue-green chlorophyll a and other pigments, many are reddish to purple from the combination.[19] The red phycoerytherin pigment is an adaptation to help red algae catch more sunlight in deep water

??

[gestaltist]

Thank you everyone for your contributions. I absolutely love what you have been sharing. I have learnt a lot! (And read all the links you’ve posted - thank you for them.)

When it comes to the planet, I think we can agree on the following consensus:
- it orbits a binary star with two dwarfs (which is as far as I am willing to go in the analysis: determining the exact star types, distances, etc., would have very little return on investment... The one thing I would like to determine, though, is how often the stars eclipse one another from the perspective of the planet. This would have major cultural impact, I am sure.)
- it is slightly warmer than Earth, so that the poles have temperate climate.
- no boiling oceans as they cannot be defended.

When it comes to the Purples:

I have been thinking about it, and it is 100% certain they would still have to eat: for one, it is completely unfeasible for an animal to subsist only on solar power due to the efficiency of photosynthesis. But also: the Purples would need an array of minerals and nutrients they wouldn’t be able to synthesize anyway.

I will settle on this: they have evolved to have some kind of porphyrin-rich fungi (?) live embedded symbiotically in their skin. Which would already happen in the womb. Said fungi would efficiently absorb the mix of wavelengths coming from the binary star, but also absorb certain elements from the air. I don’t want to get too specific about it, as I would be sure to screw up the scientific explanation. So let’s just assume that the atmosphere of this planet is slightly different from the Earth’s, allowing for this to happen. And let’s say that the Purples only need to eat half as much as humans. I know it is not probable, but I am willing to live with that one in a billion chance. The points I’ve made about the Purples’ culture thus remain valid, which is my main interest, to be honest.

The main open question for me at the moment: how would Purples and humans treat each other given their differences? Would they complement each other and create mixed societies? Would they create geographically separate civilizations? Would one group enslave the other?

I would be grateful for your input, especially from someone knowledgeable in sociodynamics.

[Zaarin]

- it orbits a binary star with two dwarfs (which is as far as I am willing to go in the analysis: determining the exact star types, distances, etc., would have very little return on investment... The one thing I would like to determine, though, is how often the stars eclipse one another from the perspective of the planet. This would have major cultural impact, I am sure.)

Note that as far as we can tell the habitable zone of a red dwarf is so close to the star that the planet will be tidally locked to its sun. Having two red dwarfs may let you push the planet out a little further, but you're still going to have very long day/night cycles (cf. Mercury). Also, there is no work involved in determining the star's spectral class: you're dealing with a M# V star (or rather two of them).

The upcoming New Horizon visit to Pluto should be most enlightening about this kind of system, where two relatively massive bodies co-orbit each other and a flock of smaller bodies orbit their common center of gravity.

The main open question for me at the moment: how would Purples and humans treat each other given their differences? Would they complement each other and create mixed societies? Would they create geographically separate civilizations? Would one group enslave the other?

Considering we have no other sentient beings to compare with, this question is anyone's guess. That they'd create mixed societies is, in my opinion, a little naïve and Roddenberry-esque. Personally I would expect that they'd interact with each other in a similar manner that one human society does with another--i.e., both war and trade--but likely with an added layer of mutual mistrust. If they were geographically separated (say, on distant continents), it could create a mutually worldview-shattering contact event.

[gestaltist]

From this thread: http://aveneca.com/cbb/viewtopic.php?f=24&t=4452

I did the numbers to get stars with 0.6 solar luminosity and 0.05 luminosity, respectively. I got a G9V and a K8V, which are yellow and orange dwarfs. Compensating for the increase in summary mass to give planetary year of 0.75 earth years, the results are pretty good, with a planet ~15 degrees cooler than Earth, ignoring greenhouse effects and albedo.

https://dl.dropboxusercontent.com/u/109 ... r00094.jpg

You get something 3 degrees (celsius) hotter than Earth if you bump the companion star up to a K4 with a mass of 0.69 solar masses. Orbital period 0.75 years, semimajor axis 0.95 AU. (It moves faster even though it's about the same orbital distance as earth because the summary mass is heavier than our sun even though their output is lower.)

The picture he links to is from some kind of space engine mod. So it is definitely possible to have a slightly-hotter-than-Earth planet orbiting a binary star, with a reasonable orbital period. I’m only wondering what the day length would be.

I also wonder if I would be able to push the size of the stars somewhat to get to a more Earth-like orbital period and day length. Sadly, I don’t even know how to start to calculate these things.

Considering we have no other sentient beings to compare with, this question is anyone's guess. That they'd create mixed societies is, in my opinion, a little naïve and Roddenberry-esque. Personally I would expect that they'd interact with each other in a similar manner that one human society does with another--i.e., both war and trade--but likely with an added layer of mutual mistrust. If they were geographically separated (say, on distant continents), it could create a mutually worldview-shattering contact event.

I don’t get your Roddenberry reference, but I do get your point. I like the geographical separation and the worldview-shattering contact event idea. I think I will put the Purples on an island where all of the flora and fauna has been „infected“ by the purple fungi. Subsequently, the fungi died out as separate beings, and only exist within the other organisms on the island. At one point, the Purples become too numerous for the island and start looking for new territory.

[Zaarin]

I don’t get your Roddenberry reference

Let's just say I find Roddenberry's kumbaya vision of the future a little...naïve, and I appreciate that DS9 came along and gave it a nice cold dose of reality. Don't get me wrong, I like Star Trek--it's just that Roddenberry's vision that we'd become perfect beings free from prejudice and conflict shows a remarkable lack of understanding of human nature.

But since that's rather off-topic, yes, I agree that the first meeting of two different sentient species has a lot of narrative potential.

[gestaltist]

Some new ideas I have developed based on your feedback:

During an Ice Age, early humans used the ice sheet to arrive to an archipelago that was otherwise very hard to access. After the Ice Age ended, they became isolated. On one of the main islands, a kind of a fungus family existed which was able to draw solar power through some kind of porphyrins, but also developed the ability to enhance that photosynthetic process through the use of the Earth’s electromagnetic field. The side effect was that they were drawn to creatures that emitted electromagnetic fields, such as humans and animals. This way the fungus started to infect some animals and the humans - and was the most successful on hairless creatures, which included the humans and some local reptilians.

(lots of mutations, evolution and hokus-pokus going on....)

The Porphyroi are born (sounds better than the Purples...) The fungus has become fully symbiotic and interwoven with them at a cellular level. Fetuses are being infected by the mother’s fungus at an early stage of pregnancy, and the fungus is especially embedded in the skin, the muscles and the digestive tract.

• the fungus draws solar power
• the fungus is breaking down toxins and improving general metabolism
• the fungus is integrating with the nervous system, giving the Porphyroi a weak ability to feel electromagnetic fields on touch. In praxis, this allows them to sense emotions of other Porphyroi when touching them.

As a result, they only need to eat once a day, about half of what humans eat. Some of the stuff they eat is poisonous to humans, but due to the fungus’ involvement in digestion, the toxins are actually beneficial to them.

I have some additional ideas but I would like to check for your feedback on the above first.

[vokzhen]

I have some additional ideas but I would like to check for your feedback on the above first.

Personally, I think in this case less in more. The more things this fungus does, the more it becomes like any other speculative-fiction superpower. Allowing photosynthesis in human-like creatures? Sure. It's interesting, and allows for interesting speculation on how they would differ from normal humans. Add immunity to toxins, enhanced metabolism, EM detection, and objective emotional sense? It's gone into magic-handwavy territory that strains credibility.

I won't comment much on the time scale - it seems far too short for me, especially for cellular-level incorporation, but I'm not knowledgeable enough except to point to chloroplasts' and mitochondria's billion-plus years - but the fungus infecting multiple species seems odd. What are the chances multiple species, encompassing highly divergent groups, all have the same immunodeficiencies that let the fungus infest the host, and (presumably) all gain use of its photosynthesis?

And one final comment, I'm of the opinion that leaving things unexplained is better than handwaving them poorly. If you say photosynthesis can be enhanced through the Earth's EM field, I'd expect you to be able to back that up with details, given how much we know about photosynthesis and the EM field. If you just say they photosynthesize more efficiently than chloroplasts, it satisfies curiosity without trapping you in something you ultimately handwave anyways (assuming that the EM field bit is just a bit of attempted explanation, without any real scientific basis).