SF worlds, what's possible, what isn't.

[Schwarzwald]

I'm embarassed to say i saw "The chronicles of Riddick" (Oh god if only I'd been in a car wreck on the way to the theater...) and remember thinking that the planet 'crematoria' could not possibly have a breathable atmosphere because, as far as we know, it takes biological activity to produce an oxy-nitro atmosphere. No plants, no free O2 since O2 is unstable and has to be constantly produced.

Some might claim that the heat on the dayside might have released O2 from rocks and such. Uh huh, and tell me when Elvis gets here.

Then there was the gas giant that Cloud City was floating in the atmosphere of in "The empire strikes back". Again, I don't think you could have a layer of breathable atmosphere in a gas giant as GGs to be made of mostly hydrogen, and hydrogen and O2 are unstable in each other's presence. Now maybe there was a layer of floating plantlife that exhaled enough O2 to create the breathable layer, but again, highly improbable, and not likely in any hard science universe.

Yavin 4, the rebel base in Star Wars, was an earth type planet orbiting a gas giant, which might be possible. One element of that was that Yavin 4 had been inhadited by an ancient, advanced race long ago, and maybe they terraformed it, or maybe a greenhouse effect kept it warm enough. It certainly appeared to have plenty of plants to keep the O2 flowing...

I'm not sure if the planet in the original Riddick movie, "pitch black' was possible, a liveable world in a quatranery system. Maybe, maybe not.

Basically, since, as far as we know, it takes an eco system to keep an Oxy-nitro atmosphere valid, it means a lifeless world can't have a breathable atmosphere barring some damn good explanation, so this rules out a lot of worlds in SF, possibly even Arrakis, AKA Dune itself.

Any other SF worlds people want to comment on or ask about?

[Thia Halmades]

According to the all mighty Wikipedia, the Chicken came before the egg. In other words, you can't have life without an atmosphere; the atmosphere on Crematoria - to take an example - could be what Wikipedia refers too as a stage two (damn, that's hot) moving on to a stage 3 (cooled by water condensation, pushing out the CO2, IIUC. You can read the article here.

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

Now whether or not that much heat would boil a human prior to being able to get a breath, that I can't say. I don't know enough AtmoSci to give you a fair clear answer.

I can say wishing you'd been in a car accident instead of seeing a movie I rather enjoyed is a bit extreme. :ugly:

[keithcurtis]

You don't have to have visible plants to sustain an O2 atmosphere. About half of ours comes from ocean phytoplankton, IIRC. Invisibly small, for all intents and purposes. In an SF world, it's not beyond reason to posit a land-based life form of comparable size on land. I've not seen some of the movies referenced above, so I can't answer anything more specifically.

Keith "breathe deep" Curtis

[OddHat]

You don't have to have visible plants to sustain an O2 atmosphere. About half of ours comes from ocean phytoplankton, IIRC. Invisibly small, for all intents and purposes. In an SF world, it's not beyond reason to posit a land-based life form of comparable size on land. I've not seen some of the movies referenced above, so I can't answer anything more specifically.

Keith "breathe deep" Curtis

At any rate, most (almost all) SF is full of bad science, both physical and social. You'd never finish listing impossibilities. If we're writing or gaming, the best we can hope for is to avoid going past the audience's ability to suspend disbelief.

[Lumbering Ox]

At any rate, most (almost all) SF is full of bad science, both physical and social. You'd never finish listing impossibilities. If we're writing or gaming, the best we can hope for is to avoid going past the audience's ability to suspend disbelief.

And thus the importance of never GMing star hero for hard core science geeks, or Fantasy hero with a bunch of SCA and professional medieval historians ;)

[David Johnston]

s far as we know, it takes biological activity to produce an oxy-nitro atmosphere. No plants, no free O2 since O2 is unstable and has to be constantly produced.

However plants need not be macroscopic. You could have a world that seems totally barren. It just isn't.

Then there was the gas giant that Cloud City was floating in the atmosphere of in "The empire strikes back". Again, I don't think you could have a layer of breathable atmosphere in a gas giant as GGs to be made of mostly hydrogen, and hydrogen and O2 are unstable in each other's presence.

I assumed that the Cloud City was surrounded by a forcefield that could keep the native atmosphere out.

Yavin 4, the rebel base in Star Wars, was an earth type planet orbiting a gas giant, which might be possible. One element of that was that Yavin 4 had been inhadited by an ancient, advanced race long ago, and maybe they terraformed it, or maybe a greenhouse effect kept it warm enough. It certainly appeared to have plenty of plants to keep the O2 flowing...

Or it could simply be a gas giant orbiting within the sun's habitable zone. In fast that's the most likely answer since it seemed very well lit.

I'm not sure if the planet in the original Riddick movie, "pitch black' was possible, a liveable world in a quatranery system. Maybe, maybe not.

It is definitely possible, although it may be improbable.

Basically, since, as far as we know, it takes an eco system to keep an Oxy-nitro atmosphere valid, it means a lifeless world can't have a breathable atmosphere barring some damn good explanation, so this rules out a lot of worlds in SF, possibly even Arrakis, AKA Dune itself.

No Arrakis isn't lifeless. Since the worms are straining the soil for food that means there have to be lifeforms living in the soil. It is however a bit problematic that Arrakis has no liquid water.

[Midas]

OK, here is one I have been skulling on.

FTR, my knowledge of planetary mechanics is feeble, my ignorance vast: I'm only going with what I have heard.

The Colonies of the Re-imagined Battlestar Galactica.

Would it be possible (very highly unlikely, but possible) that there could be up to 18 earth like planets in a standard solar system?

First we have three orbits: Venus -hot. Earth -temperate. Mars -cold. But all in theory within the life belt.

Then any could be double planets al al Romulus/Remus from that TV series.

Then there are "trojan points" in all three orbits.

OK, allowing Kobalian super-tech to nudge planets to the right positions and terraform, how rubber is my science?

Midas
PS: Shall I bring up the Firefly system? ;)

[Basil]

Then there was the gas giant that Cloud City was floating in the atmosphere of in "The empire strikes back". Again, I don't think you could have a layer of breathable atmosphere in a gas giant as GGs to be made of mostly hydrogen, and hydrogen and O2 are unstable in each other's presence. Now maybe there was a layer of floating plantlife that exhaled enough O2 to create the breathable layer, but again, highly improbable, and not likely in any hard science universe.
I don't remember anything in the movie that stated Baspin (is that the right name?) was a gas giant. It may have been a more-or-less Earth-sized body, with an extensively clouded atmosphere. Certainly the characters did not act as if they were under the effects of a gravity as strong as a GG would have.


Yavin 4, the rebel base in Star Wars, was an earth type planet orbiting a gas giant, which might be possible. One element of that was that Yavin 4 had been inhadited by an ancient, advanced race long ago, and maybe they terraformed it, or maybe a greenhouse effect kept it warm enough. It certainly appeared to have plenty of plants to keep the O2 flowing...
For another dicussion of inhabitable sattelites of GGs, see this thread. http://www.herogames.com/forums/showthread.php?t=45509

[Basil]

OK, here is one I have been skulling on.

FTR, my knowledge of planetary mechanics is feeble, my ignorance vast: I'm only going with what I have heard.

The Colonies of the Re-imagined Battlestar Galactica.

{snip}

Then there are "trojan points" in all three orbits.
One thing about Lagrange (aka Trojan) points. For them to work, body B (the second-most massive) must be no more than approximately 1/26 the mass of body A (the most massive), and body C (the smallest) must have an insignificant mass relative to A and B.

If you were to move, say, Luna to the leading Trojan point in the Sol-Earth system, its gravitational effect on Sol and Earth would fairly rapidly lead to a breakdown of the system, and Luna (and conceivably Earth) would go flying off who-knows-where.

In short, you can have plenty of inhabited sattelites in the Trojan points, but nothing planet sized.

[Midas]

One thing about Lagrange (aka Trojan) points. For them to work, body B (the second-most massive) must be no more than approximately 1/26 the mass of body A (the most massive), and body C (the smallest) must have an insignificant mass relative to A and B.

If you were to move, say, Luna to the leading Trojan point in the Sol-Earth system, its gravitational effect on Sol and Earth would fairly rapidly lead to a breakdown of the system, and Luna (and conceivably Earth) would go flying off who-knows-where.

In short, you can have plenty of inhabited sattelites in the Trojan points, but nothing planet sized.

Ah ok, Thank you Basil.

Let's carry the speculation onward. Re a nearby thread: Could you put a Jovian planet (I'm thinking of whatever those things are that astronomers have found orbiting nearby stars), with a habitable moon, in Earth's orbit at point "A", and then put Earth at point "B", and Luna at point "C"?

Midas

[Basil]

Ah ok, Thank you Basil.

Let's carry the speculation onward. Re a nearby thread: Could you put a Jovian planet (I'm thinking of whatever those things are that astronomers have found orbiting nearby stars), with a habitable moon, in Earth's orbit at point "A", and then put Earth at point "B", and Luna at point "C"?

Midas
No. The requirement is that body C have a mass that's insignificant compared to A or B. Insignificant in this instance means <.00001, at the least.

Now, if Earth were orbiting Jupiter, there would be Trojan points in the Jupiter-Earth system, since Jupiter's mass is ~317 times that of Earth.

[keithcurtis]

Was there anything that said the 12 colonies of the new BSG were in the same star system?

Keith "Been too long since I saw the pilot" Curtis

[Schwarzwald]

Was there anything that said the 12 colonies of the new BSG were in the same star system?

Keith "Been too long since I saw the pilot" Curtis

No, there wasn't, and given the sheer number of FTL capable ships in the colonial system I'd say it was a fair bet that the colonies may have been within several star systems a light year or so apart, possibly farther down the galactic arms where star density increases.

[Schwarzwald]

According to the all mighty Wikipedia, the Chicken came before the egg. In other words, you can't have life without an atmosphere; the atmosphere on Crematoria - to take an example - could be what Wikipedia refers too as a stage two (damn, that's hot) moving on to a stage 3 (cooled by water condensation, pushing out the CO2, IIUC. You can read the article here.

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

Now whether or not that much heat would boil a human prior to being able to get a breath, that I can't say. I don't know enough AtmoSci to give you a fair clear answer.

I can say wishing you'd been in a car accident instead of seeing a movie I rather enjoyed is a bit extreme. :ugly:

Early earth had a promordial, reducing atmosphere, similar to what you find on titan today. I think it was methane and nitrogen. Early lifeforms over millions of years produced oxygen by liberating it from iron oxide in the oceans, putting the O2 in earth's atmosphere.

[TheRavenIs]

It is theroitical that a silcon based life form or even a carborn based ones could exist in the temp's we saw on 'crematoria' but for it to process material and then create oxygen as a byproduct would seem to violate the understanding of both organic and inorganic chemistry, until you consider the plant's and animals living under the pressures and temp's of the deep trenches of our own oceans. They would have to be microscopic in nature and use chemical means to live. Also the microscopic life in super-heated pools like in Yellowstone.

[Nolgroth]

Was there anything that said the 12 colonies of the new BSG were in the same star system?

Keith "Been too long since I saw the pilot" Curtis Not sure if all of the twelve colonies are in the same system, but at least Caprica and Virgon were. In the pilot, the Sec. of Education (future president) leaves Caprica with around three hours flight time to Galactica. Also in the pilot, just after the initial attack, Virgon is about an hour away from the Galactica.

Still watching the pilot again and I will update as I get more info.

-James

[keithcurtis]

These travel times were in ships known to have no FTL? Even vipers and raptors have FTL.

Keith "?" Curtis

[Nolgroth]

These travel times were in ships known to have no FTL? Even vipers and raptors have FTL.

Keith "?" CurtisRaptors do have FTL, but Vipers do not. Most of the discussion in travel times were before Adama decided to start using FTL. The Ragnar ancorage was also a few hours from the Galactica's position by normal travel.

Also, it's nothing conclusive, but when Adama told the command crew that they were running instead of fighting, he said that "they were going to leave this solar system....." It doesn't outright confirm anything, but I took that statement to imply that the twelve colonies were right in the same system.

Also, I'm not sure if they have FTL communications or not. If not, then all of the planets would seem to be rather close together for the Galactica to get reports from all of the colonies about their status.

Just my observations. Make of them what you will.

[Midas]

Raptors do have FTL, but Vipers do not. Most of the discussion in travel times were before Adama decided to start using FTL. The Ragnar ancorage was also a few hours from the Galactica's position by normal travel.

Also, it's nothing conclusive, but when Adama told the command crew that they were running instead of fighting, he said that "they were going to leave this solar system....." It doesn't outright confirm anything, but I took that statement to imply that the twelve colonies were right in the same system.

Also, I'm not sure if they have FTL communications or not. If not, then all of the planets would seem to be rather close together for the Galactica to get reports from all of the colonies about their status.

Just my observations. Make of them what you will.

Indeed. Raptors have FTL, and some ships have FTL. Vipers and many ships don't. Remember that the survivors were forced to leave the slow boats behind (and how many were massecred?). So some of the Colonies were close enough that it was practical to have passenger vessals traverse in between.

TPTB have been cagey about whether the Colonials have FTL communications, but it has been hinted at that they don't. OTOH, there is some indication that the Cylons do. Or else they have raiders close to the fleet picking up spy transmissions and Final Uploads.

They have also been cagey about how many systems make up the Colonies. Personally, I am of the opinion that the colonies are located in a "globular cluster" of some kind, with stars quite near each other, but I was speculating on how you could have twelve habitable planets in one system.

Re: The Lagrange points, Basil that works! You can have 12 habitable planets in one system. Work it this way: Three Jovian planets in the "green belt" with one to three habitable moons each. Put a single or double planet in the second Lagrange point of each orbit. Nothing notable need go into the third. (BTW I'm just arguing this as a mental exercise; I doubt that the Kobolians had the kind of tech to nudge planets, though they might have been mighty terraformers ((Koboliformers?))).

Also, I'm being generous with the definition of habitable. I get the impression that Geminon is similar to a pulp era Venus, and that Sagiton barely qualifies as habitable. I'm visuallizing something like Mars in that Ahnald flick.

Midas

[Basil]

Early earth had a promordial, reducing atmosphere, similar to what you find on titan today. I think it was methane and nitrogen.
Earth's early atmosphere was neither primordial nor reducing. It was CO2, N2, H2O, and a whiff of other stuff. This is not a reducing atmophere, unlike a comination of NH3 and CH4, which is what it was believed to have been up until the 1950's and 1960's.

Nor is it primordial; this is, left over from the condensation from the proto-stellar nebula. Indeed, due to the late heavy bombardment (the very last stage of planetary accretion), the Earth's atmosphere was boiled away more than once, and what is here now is the product of the last few planetesimals to impact Earth (and the processes of life and nuclear decay, of course).
{Citation: World-Building by Stephen L. Gillett}


Early lifeforms over millions of years produced oxygen by liberating it from iron oxide in the oceans, putting the O2 in earth's atmosphere.
Citation please? I've never heard of any significant source of O2 other than photosynthesis.

[keithcurtis]

From the BSG Wiki:

Approximately 2,000 years ago, twelve of the thirteen tribes of Kobol settled on nearby worlds (Kobol's Last Gleaming, Part I). Their names and icons originally corresponded to the twelve signs of the ancient tribes although these names drifted over time. (Home, Part II).
Although Commander Adama and President Roslin mention leaving the solar system, it is unclear whether all twelve Colonies are orbiting a single star or what the name of this star might be. (Miniseries)
The semi-canonical 2003 Video Game names the home system for the Twelve Colonies as Cyrannus but this has yet to be confirmed in the new television series. In an early script of the re-imagined Battlestar Galactica Miniseries, the Twelve Colonies were originally located on a single world - Kobol. However, this was later revised to twelve separate worlds, in keeping with the original concept.
Ronald D. Moore has suggested that the Colonies probably maintained some minor observatories and listening posts in outlying star systems, but it is unlikely that Galactica will encounter them in the course of the series. (January 30, 2005)
So, not conclusive, but leaning toward one system. Midas was clever to bring up the Firefly system, since this is also a single system group of habitable worlds. Since we only have one solar system with hard data, and only the merest scraps of info on about fifty more, a large number of terraformed or even naturally habitable planets doesn't stretch my credulity to the breaking point. Particularly when it's not a central point of scientific necessity. "There were some colonies. They got blowed up. Here's what happened to the survivors."

As for Vipers with FTL, I had thought the Laura had FTL. Then I remembered that Starbuck went back to Caprica in the captured Cylon ship.

Keith "Would like to see some theories for mega-populous planetary systems" Curtis

[David Johnston]

It is not possible for a world with a transparent atmosphere to not have a blue sky (when clear). Andre Norton's pink skied world? Not possible.

It is not possible to see the "colour" of a sun with the naked eye. It'll look white to you. Darkover's visibly red light? Not possible.

It is not possible to have a planet rotate so fast as to make a radical difference between the gravity at the equator and the poles. Mesklin? Would fly apart. And wouldn't have any solid ground anyway

[BlackSword]

Then there was the gas giant that Cloud City was floating in the atmosphere of in "The empire strikes back". Again, I don't think you could have a layer of breathable atmosphere in a gas giant as GGs to be made of mostly hydrogen, and hydrogen and O2 are unstable in each other's presence.

I assumed that the Cloud City was surrounded by a forcefield that could keep the native atmosphere out.

Which is a reasonable assumption as we have seen transparent force fields on the Death Star allow ships to pass but keep the atmosphere inside the landing chambers.

[austenandrews]

It is not possible for a world with a transparent atmosphere to not have a blue sky (when clear). Andre Norton's pink skied world? Not possible.
By "transparent" and "clear" I assume you mean barring gases/vapors/particulates not found on Earth? You can have any color of sky you want with the right materials in the air.

[Nyrath]

It is not possible for a world with a transparent atmosphere to not have a blue sky (when clear). Andre Norton's pink skied world? Not possible.
Oh, it's possible all right. It just isn't breathable. ;)

[BlackSword]

It is not possible for a world with a transparent atmosphere to not have a blue sky (when clear). Andre Norton's pink skied world? Not possible.
The Martian sky is not blue and it has enough of an atmosphere to support dust storms. (APOD has several other pictures of Mars, but this is first that said it was real-color). As Nyrath says, its not breathable, but the sky is not blue.

http://antwrp.gsfc.nasa.gov/apod/ap050822.html

[Schwarzwald]

Earth's early atmosphere was neither primordial nor reducing. It was CO2, N2, H2O, and a whiff of other stuff. This is not a reducing atmophere, unlike a comination of NH3 and CH4, which is what it was believed to have been up until the 1950's and 1960's.

Nor is it primordial; this is, left over from the condensation from the proto-stellar nebula. Indeed, due to the late heavy bombardment (the very last stage of planetary accretion), the Earth's atmosphere was boiled away more than once, and what is here now is the product of the last few planetesimals to impact Earth (and the processes of life and nuclear decay, of course).
{Citation: World-Building by Stephen L. Gillett}


Citation please? I've never heard of any significant source of O2 other than photosynthesis.

http://www.universetoday.com/am/exec/view.cgi/1/2771

[Cancer]

I have problems with the very first linked page.

There's stuff besides ozone that blocks UV just fine.
There's powerful geochemical evidence that Earth before about 2.4 Gyr ago had a radically different, more or less free of molecular oxygen, chemistry; one citation (www.sciencemag.org/cgi/reprint/298/5602/2341.pdf). The change seems to happened in the 2.4 - 2.1 Gyr ago time range.
Those citations in the linked page are pretty old ... 1980's, I see one 1990 citation. That's grossly out of date for this topic, and there are way too many citation of the same author.

Gah, on the 3rd page it becomes clear that's a creation science site. :sick:

[Schwarzwald]

I have problems with the very first linked page.
There's stuff besides ozone that blocks UV just fine.
There's powerful geochemical evidence that Earth before about 2.4 Gyr ago had a radically different, more or less free of molecular oxygen, chemistry; one citation (http://www.sciencemag.org/cgi/reprint/298/5602/2341.pdf). The change seems to happened in the 2.4 - 2.1 Gyr ago time range.
Those citations in the linked page are pretty old ... 1980's, I see one 1990 citation. That's grossly out of date for this topic, and there are way too many citation of the same author.Gah, on the 3rd page it becomes clear that's a creation science site. :sick:

Yeah, yeah, I know, I pasted thge wrong link first time. I corrected it now.

You know, this is one thing I hate about the net. You make a statement, someone asks for a rewf, you must then spend time and effort looking for a link pasting it into a reply, etc. Making you someone's unpaid researcher.

I will not link to a site about how the first O2 in earth's atmosphere came from microbes breaking up iron oxide, he can fid that himself. I

[Cancer]

Ah, OK. Looking at the corrected link, I have no problem with that.

Sorry to pounce so quick on a mistake that got edited away.

[Schwarzwald]

Ah, OK. Looking at the corrected link, I have no problem with that.

Sorry to pounce so quick on a mistake that got edited away.

's OK, I'm not some whiney little beeyotch that runs crying to a mod anytime anyone says anything I find 'offensive', especially since I posted the wrong link in the first place.

[David Johnston]

The Martian sky is not blue and it has enough of an atmosphere to support dust storms. (APOD has several other pictures of Mars, but this is first that said it was real-color). As Nyrath says, its not breathable, but the sky is not blue.

http://antwrp.gsfc.nasa.gov/apod/ap050822.html

Looks like a dust cloud to me. But yes, I should have added "in an atmosphere of earth-like density in the daytime".

[Nolgroth]

's OK, I'm not some whiney little beeyotch that runs crying to a mod anytime anyone says anything I find 'offensive', especially since I posted the wrong link in the first place.I'm tellin' the mods; MAAAAAADS! :D (Sorry I just couldn't help it. Well, probably could have, but I chose not to.)

[Schwarzwald]

As to a liveable world having a non-blue sky, I wonder if one orbiting a star with a different spectra than Sol would have a different colored sky? it's the preferential scattering of blue rays that makes earth's sky blue, yes, so if a star had less blue in it's spectrum the color of a world's sky that oprbited might be diffetent, yes?

[BlackSword]

You know, this is one thing I hate about the net. You make a statement, someone asks for a rewf, you must then spend time and effort looking for a link pasting it into a reply, etc. Making you someone's unpaid researcher.
Not to jump on you, but providing a reference when someone asks for one is not being their unpaid researcher its backing up your statements. If its a subject I am interested in then I:
a) want to read more about it, obviously since the poster knows about this subject with such authority to post on it, they have some reference that I can refer to
-or-
b) have read a contradictory theory and would like to compare the two theories, this time I need to know exactly which theory was posited by the other poster

Does it mean writing a thesis on the subject? No. It does mean backing up statements with something substantial.

[Cancer]

As to a liveable world having a non-blue sky, I wonder if one orbiting a star with a different spectra than Sol would have a different colored sky? it's the preferential scattering of blue rays that makes earth's sky blue, yes, so if a star had less blue in it's spectrum the color of a world's sky that oprbited might be diffetent, yes?
In principle, yes. Computing what sort of star you need to get what color is a nasty problem (I looked into that once).

If photochemistry is important to your atmosphere (and it usually is :rolleyes:) this will bring in other effects as well ... less blue light means an even smaller amount of UV, and UV is the "big dog" for photochemistry. That means that trace compounds normally removed by those processes will build up, and that could make for an unexpected change in overall atmosphere composition (which could change your assumption about the atmosphere being transparent enough that Rayleigh scattering controlled the sky color).

The amount of blue & UV in a stellar spectrum doesn't scale easily with spectral type or effective temperature for stars cooler than the Sun, though. There's a temptation to try using something simple like the Planck function for the spectrum of a star, and that turns out to be a truly terrible approximation for the wavelengths shorter than the peak.

[Basil]

Not to jump on you, but providing a reference when someone asks for one is not being their unpaid researcher its backing up your statements. If its a subject I am interested in then I:
a) want to read more about it, obviously since the poster knows about this subject with such authority to post on it, they have some reference that I can refer to
-or-
b) have read a contradictory theory and would like to compare the two theories, this time I need to know exactly which theory was posited by the other poster

Does it mean writing a thesis on the subject? No. It does mean backing up statements with something substantial.
Thank you for putting it more politely than I had planned to. :thumbup:

[Basil]

Sorry I missed this one earlier.


Re: The Lagrange points, Basil that works! You can have 12 habitable planets in one system. Work it this way: Three Jovian planets in the "green belt" with one to three habitable moons each. Put a single or double planet in the second Lagrange point of each orbit. Nothing notable need go into the third. (BTW I'm just arguing this as a mental exercise; I doubt that the Kobolians had the kind of tech to nudge planets, though they might have been mighty terraformers ((Koboliformers?))).

First, an important nit-picking: there are 5 Lagrange points. Those numbered 1 through 3 are in line with bodies A and B. They are only stable under very, very restricted conditions: conditions not to be found in the Real World™. The 4th and 5th L. points are stable in somewhat restricted conditions, which are found in the Real World™.

Now, the important point is this---if you have a Jovian circling a star, the L4 and L5 points are stable only for low(ish) mass objects. Nothing bigger than a moderate-to-smallish asteroid can be put in either place. You can not have a planet there; not if you want it to stay there.

[keithcurtis]

In When World Collide, and the Sequel, "After Worlds Collide", the sky has a greenish tinge. This puzzled the colonists (since it should not have been possible) until winter came and brought the first green "rain". It seems Bronson Beta had a high altitude photosynthetic organism. Made hell for astronomical observation, but did provide several inches of fertilizer every year.

Keith "Wylie and Balmer fan" Curtis

[Nyrath]

In When World Collide, and the Sequel, "After Worlds Collide", the sky has a greenish tinge. This puzzled the colonists (since it should not have been possible) until winter came and brought the first green "rain". It seems Bronson Beta had a high altitude photosynthetic organism. Made hell for astronomical observation, but did provide several inches of fertilizer every year.
Yeah, I though of that old classic too, but didn't want to confuse the issue.
Just to be pessimistic, one wonders if the colonists discovered a new disease called "green lung".

Now I'm going to have to go find my copies and re-read them. The movie was fair, but the books were better. Kind of extreme for a Star Hero campaign, though.