Okay, as an extension of my previous question, I'm just going to lay bare all the details I've written down about this planet (including corrections from my last question), and ask the big question that needs to be answered about this planet. Can it support life, and if so could humans colonize it without resorting to wearing space suits or building bubble habs?


Physical characteristics:

  • Earth-like exoplanet located 600 light years from Sol in the sextenary star system Messina 2247
  • Mass is $1.696*10^{24} \text { kg}$ or $.284$ Earths, resulting in a surface gravity of approximately $.66 \text { g}$, or $6.44 \text { m/s}^2$
  • Planetary diameter of $8380 \text { km}$, with an orbital radius of $1 \text { AU}$ around its mother star, Scylla β

Side Note: Scylla β is the second ordered star in the Messina system that orbits the black hole Charybdis as part of an ordered sextenary (six star) hierarchy; the hierarchy is made up of six stars designated Scylla α - ζ (each $.1 \text { ly}$ distant to each other), while Charybdis is the primary mass around which they all orbit, with an approximate mass of $315 \text { Suns}$

  • Atmosphere is $35\% \text { oxygen}$, $61\% \text { argon}$, $1.07\% \text { carbon dioxide}$, and $.93\% \text { arsenic}$ particulates, as well as other trace elements which make up the remaining $2\%$
  • Due to a bombardment of high-energy particles from the star Charybdis going hypernova during the early stages of the planet's formation, the planetary crust of Anthemusa is laced with negative mass exotic matter which can be extracted to fuel warp drives as well as other negative energy/antigravity technologies

Environmental hazards:

  • Atmosphere is easily breathable after acclimatization but has had some unfortunate side-effects on the planet, like gigantism in local fauna similar to the prehistoric epochs of Earth (also due in part to microgravity and the bizarre effects of exposure to exotic matter during the early stages of evolution) and a drastically increased risk of out of control forest fires, as well as arsenic smog

  • Atmospheric composition also causes metal to rust faster, and food to spoil more quickly. However, after acclimatization, the higher oxygen levels result in increased stamina and endurance. It also increases the rate at which cells decay however, resulting in a moderate reduction in overall life expectancy and an increased risk of cancer (gene therapy has mitigated these effects somewhat)

  • Because of the thin diffusion of arsenic smog over the planet, the poisonous particulates mix frequently with large bodies of water, making all non-filtered water poisonous unless it's extracted from deep underground. The smog can also increase in density from time to time, resulting in roving clouds of toxic poison that will occasionally pass through the forests, killing anything that breathes it.

  • Exceptionally large deposits of exotic matter can occasionally lead to the formation of large floating landmasses that are lighter than air due to their negative mass.
  • Anthemusa's sextenary star system makes a true night rare, and often the only reprieve from the sunlight on the planet are brief periods where it becomes slightly dimmer as the number of suns overhead decreases; most animals on Anthemusa are cold-blooded as a result, as warmth from the suns is always plentiful.

Please let me know what you think, and if there's anything about this planet as I've described it that doesn't make much sense from a scientific standpoint.

EDIT: Also I've just started using this site, so please bear with me while I figure out the formatting :)

  • $\begingroup$ I've made a few edits to your post to improve readability. Feel free to take a look to get a feel for the syntax. If you disagree with my edits, feel free to roll them back. $\endgroup$
    – Frostfyre
    Jun 20, 2016 at 18:53
  • 1
    $\begingroup$ Welcome to the site! You may get more focused answers by breaking this into two questions, one for xenobiology and one for human colonization $\endgroup$
    – Kys
    Jun 20, 2016 at 19:26

5 Answers 5


I wish I had an eloquent answer, but I don't.

My first two concerns would be the true availability of 'Daylight', which would impact all aspects of habitability from a Human point of view. At an average of 587 Billion miles apart, the 'normal' stars are likely to be little more than bright points of light, so reliance on the primary would be implied.

The second concern is that Black Holes ( in theory) are known for ravenously absorbing any matter that crosses its path, often resulting in a trade off for Gamma ray emissions as the object accelerates near the event horizon. Arsenic clouds aside, one gamma ray burst would make the other challenges pale by comparison.

I think the most intriguing question beneath it all is a simple "why there?"

It would of course make a spectacular observation outpost that most Physicists would gladly accept these risks for a chance to study the system from such a vantage, but if this is a colonization for the sake of brave new worlds, seems a bit harsh environmentally.

  • $\begingroup$ The colonists are actually there to establish an outpost for exotic matter mining (when normally it can only be harvested as particulates in deep space), so the risks are justified when you're sitting on a giant ball of warp drive fuel. As for the stars and the black hole, I was advised on Physics Stack Exchange that a sextenary star system with the orbits closer together would negatively affect the development of life on the planet. Is this true? Also, a black hole was the only object massive enough to have six stars orbiting it that I could think of besides really short-lived giant stars. $\endgroup$ Jun 20, 2016 at 21:02
  • $\begingroup$ From where did you get the figure 587 billion miles? $\endgroup$
    – user
    Jun 21, 2016 at 14:44
  • $\begingroup$ Warp drive fuel would explain it - the mining operation would likely then be a more 'frontier' settlement than a holiday vacation spot. I came up with the 587 billion miles as an 'average of 0.1 light years', at which distance, most stars are just that - stars, and although a clear night might see a double shadow or three, if the orbital paths of the other stars are stable, surface climate would depend on the primary. I have no verifiable information on the evolutionary backlash of the systems' mechanics, but it seems that there would always remain the possibility of heavy Gamma radiation... $\endgroup$
    – Joe
    Jun 21, 2016 at 19:07

This planet seems habitable, with the biggest survival issue coming from the roving poison clouds. Colonists would be able to travel without special environmental suits most of the time, but would certainly need some form of airtight shelters/habitats to ride out arsenic storms. They would also need a reliable way to filter their water supplies.


If they want to grow crops on your planet, the humans are going to have to either (a) make arsenic-free soil, or (b) work out how to stop plants absorbing the arsenic. Paper on arsenic uptake in plants

So the people might not be in bubble habs, but their vegetables will be!


I don't see a reason the planet couldn't support life, as long as it has liquid water. You seem to have thought it through quite well, and I'm not a professional in any sense. One thing I will give my opinion on, though:

I think it would be reasonable to assume that most of the native flora and fauna would have evolved ways to deal with or withstand the arsenic.

While it's unlikely that humans could simply eat an entirely alien species, gene therapy and splicing might be used to give earth produce the arsenic-resistant properties? These could be a simple process filtering out the arsenic before it is absorbed by the plant, or binding the arsenic to another substance and excreting it in some way.

It depends on the advancements of science in your universe. Genetic manipulation is one thing when you're talking about life from the same planet, but from different planets I imagine it's a lot more difficult.


Can it support life?

Provided liquid water and a strong enough magnetic field is present, the likelihood of such a planet being able to support some sort of flora and fauna is quite high. In the end it depends on the characteristics of the star(s), though.

The black hole does make it a challenge, though,because of the various forms of radiation that these emit, including gamma radiation. Life may be able to compensate for this.

If so could humans colonize it without resorting to wearing space suits or building bubble habs?

If we consider "vanilla" first-gen colonizing humans from Earth:

Depending on the actual atmospheric pressure, they may be able to wander around on the planet without a space suit, but they might, at the very least, require some sort of mask to weed out the arsenic particulates.


The argon content of the atmosphere is where I would raise a few doubts. There isn't really anything that covers human survivability in a largely argon-based atmosphere - much less long-term. We do have a 1% concentration of argon in the Earth's atmosphere, but that is a far cry from the 61% of Anthemusa's atmosphere.

However, in theory, it should be perfectly breathable in those concentrations, as it acts chemically similar to classic dinitrogen which composes much of our atmosphere.

Carbon Dioxide

Humans can adapt to CO2 levels around 2%, which is considered somewhat acceptable in enclosed spaces - however, this is again considering that most work environments only allow humans to work under these conditions for a set amount each day. Even a somewhat acclimated first-generation human settler will feel some side-effects from the high CO2-levels. This is especially true for people working on submarines or space stations for long stretches of time. While the body adapts somewhat (eg. altered breathing), it can still end in bouts of dizziness or migraines/headaches. Along with that comes a general reduction in mental capacity when working for a long time in a CO2 rich environment. That said, the added oxygen content may compensate for this.


This is where I really have doubts. While arsenic does exist in some form in most of our food and water, it's vastly different from actually breathing it. Depending on what constitutes said particulates, the arsenic may also contaminate drinking water on the planet - however this can be compensated for somewhat by treating the water. As you mention, sources from deep underground is also an option, however, you have to consider that groundwater also gets contaminated by arsenic, especially in an environment that contains hundreds to thousands of times more arsenic than here on Earth.

This is also the main reason that some sort of filtration mask would be needed when moving about in Anthemusa's wilderness.

In any case, habitation areas would need to compensate for the dense arsenic smog in some capacity (especially if they grow to town- or city-size), and settler morale could be boosted somewhat by having recreational areas where masks are not needed. Some sort of isolated enviroment (greenhouses) would also likely be needed for crops - especially if low arsenic content is desired. That said, hab domes can stillbe constructed in a simpler manner than, say, anything needed to colonize Mars or even something like the Biosphere 2 project - something more like some of the "wildlife domes" that can be found in some places, like Randers Regnskov here in Denmark, would probably be sufficient. Youalready have (mostly) the right gas mix - it's the arsenic that's the real dangrous part.

Apart from local flora - local fauna should also be eaten with caution, as they are likely to contain higher arsenic levels than Earth life.

The first settlers on Anthemusa will likely get problems with long-term arsenic poisoning - however, later generations may develop a tolerance to the high arsenic levels of Anthemusa's atmosphere and wildlife. Alternatively genetic modification in some capacity has been put on the table.

However, you do write:

The smog can also increase in density from time to time, resulting in roving clouds of toxic poison that will occasionally pass through the forests, killing anything that breathes it.

I'm certain, if local flora and fauna has dealt with this for millions or billions of years, evolution has taken care of this in some way.

More on arsenic poisoning can be found here


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