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41

Religion Some book considered holy and written long ago claims some deity created that specific planet, and then all sorts of creatures and finally humans on it. So the inhabitants of Eden think they have been expelled from the Garden of Earth, without ever realising that Earth is another planet.


32

Time This is normally done with the application of a few hundred years, technological collapse and a migration of the population away from any physical artifacts of interplanetary travel. Technological collapse takes away all their records, even if they reinvent computers later they probably won't be able to read the old records. The technological collapse ...


28

It only takes a generation or two before that which may once have seemed foreign may then be seen as something that was always there. For example, in our daily lives, we don't think about how certain food items aren't native to our current homes, yet mere centuries ago, pineapples were a luxury. We take things for granted, and that's something that can ...


13

Could a star exist with this cloud similar to earth atmosphere around it where a person could breathe without much effort? Nope. The solar wind and radiation pressure and a combination of planetary and stellar gravity would either blow away or hoover up all the gas cloud in relatively short order. That's why there's a fairly hard vacuum between planets in ...


12

Estimates for the mass of the Chicxulub impactor that offed the dinosaurs range from 1015 and 4.6 $\times$ 1017 kilograms. The hydrosphere's mass is currently estimated to be around 1.4 $\times$ 1021 kilograms. That is like 10,000 Chicxulubs in terms of orders of magnitude, if we use the upper bound for Chic's mass. Might be more like 100,000 dino-killing ...


10

Infrared, Sonar, and Other Waves Some animals use "bio sonar", or echolocation as a form of "sight" (ie, navigating and foraging). It's also possible for your creatures to see infrared radiation. If fact, your creatures could emit small amounts of waves from just about anywhere on the electromagnetic spectrum, except for visible light, and therefore "see" ...


10

I do not believe that any form of EMP would prevent electrical technology, as the EMP would induce currents in metals which might attract attention and at some point metal screens would be discovered. But there is one possible way that does not use EMP. If all of the common metals accessible by smelting such as iron, copper, zinc, lead, nickel etc were ...


10

No tools to build tools. The surviving ships had a limited supply of spare parts and no means to make more. Once the capacitor on the ciruit board of the 3D printer goes bad, that thing is completely useless. Perhaps the engineers realized that, and tried to 3D-print old-fashioned turret lathes and printing presses with the starship workshops. But then ...


9

So, lets say there's about $1.8*10^{21}$kg of water on the surface of the earth (this excludes hydrates and stuff in the mantle, but the surface stuff seems like the bit most likely to be deposited by impacts after earth's formation). Given the density of ice, $920kg/m^3$, that much water would form a solid sphere about 776km in radius. That's Quite Big, by ...


9

would the ore itself be different in such an environment? Pretty much all the iron ores on Earth are oxides and hydroxides. No oxygen, no water, no conventional iron ores. (I listed a few of the common ores in another answer of mine with various relevant wikipedia links; I shan't copy it all out here). If you had water, you'd have a ready supply of oxygen, ...


9

Answer is very simple: Glacial Period. Most of the water would be captured in polar glacials, while at equator it would be very dry, extremly hot at daytime desert. There were such a situation on Earth during (last) glacial period (our oceans are to deep to dry out, but some water bodies did). UPD: There still be rivers flow from glacials wich will bring ...


8

A planet composed of 90% or more of metals is not that unlikely. The planet Mercury is composed of 70% metals with the majority of the lighter non-metals being concentrated in the relatively thin crust and the mantle. The crust and a lot of the mantle could be removed by an energetic collision with another large planetary body which could disrupt the ...


7

Electromagnetic or magnetic induction is the production of an electromotive force (i.e., voltage) across an electrical conductor in a changing magnetic field. This is correct, but the operative word here is "changing". Specifically, Faraday's law states $$\nabla \times \mathbf{E} = - \frac{\partial \mathbf{B}}{\partial t}$$ If you're not familiar with ...


7

No to the star, Yes to the travel A star cannot exist in that type of atmosphere for many reasons. Not the least of which is heat. Temperatures range into the millions of degrees, which destroys any chance of a stable atmosphere. Furthermore, any particles in the air would result in continual dust explosions. This of course does not mention issues with ...


7

Civilization collapse. Societal collapse triggers a drastic reduction is specialists which triggers a loss of knowledge. It has happened in the past, (the bronze age collapse), and a lot gets lost during collapses. There is evidence many bronze age societies lost writing, which is pretty big loss. Now oral tradition may preserve some knowledge they will ...


7

A Fresh Start + Propaganda The planet was settled by some (take your pick) Religious Fanatics/Idealistic Utopians/Persecuted Cult/Tyrannical Government/Other Group that wanted to cut all ties to old earth to Get Away From the Heretics/Create Plato's Republic/Escape Persecution/Form the Perfect World Order. The entire crew of the ship has agreed to keep the ...


6

There had been many attempts at colonization of other worlds. All of them failed. As it turned out, the settlers just couldn't cope with the traumatic stress of being separated from the home world by incomprehensible cosmic distances, and living under a strange, subtly wrong sun. For this reason, a new colonization program was started, where the settlers ...


5

Yes it could be out of plane Astronomers are reporting today the discovery of a planetary system way out of tilt, where the orbits of two planets are at a steep angle to each other. This surprising finding will impact theories of how multi-planet systems evolve, and it shows that some violent events can happen to disrupt planets' orbits after a planetary ...


5

This is Jupiter after being hit by Shomaker-Levy 9 in 1994: It smoothed out in days, but hey, there you have dark spots. A constant bombardment would do for a fictional planet. Edit: while researching something else, I came across this time lapse of Voyager 1 approaching Jupiter in 1979. There are many dark spots at the boundary between the north pole and ...


5

FOG1 Should FOG1 look like Venus, it is because it will in some aspects be similar to it and because this is an image of Venus. :) FOG1 is a predomenetly metallic (read 90%+) super-earth orbiting a long lived, dim K-Type star. Its planetary attributes are: $$M = 7,5 Me$$ $$R = 1,3871 Re$$ $$gravity = 3,898 G (38,228 m/s^2)$$ $$Vescape = 26 km/s$$ Its ...


5

[Handwavium explanation] Without Oxygen, you will have a hard time burning the hydrogen to create a fire. Since you do not mention the composition of atmosphere, one possible way you can achieve the Firestorm could be via a sudden outburst of oxygen in the atmosphere leading to the right conditions, which are otherwise absent. This could be due to ...


5

This depends a lot on why electric or electronic devices don't work or can't be developed. The fundamental principles of electricity tie deeply into the other foundations of physics (it's tempting to try and say "there is no electromagnetism so you can't make generators", for instance, but if you get rid of magnetism then you also get rid of light, which ...


5

It would be unbelievable if they had kept their technology after several unplanned and under-equipped diasporas. Advanced technology is not just a bunch of technical lesson plans which can be casually carried along in every ship's computer. It is also the undocumented wisdom of experienced practitioners in hundreds of distinct disciplines. Beyond that, ...


5

I can see four key problems with the system as you've described it: Giant planets. The major thing that concerns me about the system is the presence of at least two gas giants. It's long been thought that low-mass stars like red dwarfs are unable to form giant planets, because the stars' protoplanetary disks are generally low-mass, and there's simply not ...


4

Gases Gas, Color - Helium: White to Orange; under some conditions may be Gray, Blue, or Greenish-blue. - Neon: Reddish-orange - Argon: Violet to Pale Lavender Blue - Krypton: Gray, Off-White to Green. At high peak currents, bright Bluish-white. - Xenon: Gray or Bluish-gray, dim White. At high peak currents, very bright Greenish-blue. - ...


4

I see no particular reason why an iron world or a carbon world should be unsuited to ammonia oceans. The big problem with an iron world is how you get one that has significant quantities of any volatiles at all. But if you posit, e.g., that shallow oceans were deposited by cometary bombardment after if formed, you're fine. Iron will rip the oxygen right out ...


4

You don't need to remove the oxygen from the planet, just take it out of easy circulation. The oxygen trapped in rocks is actually exactly where you want your oxygen. Now, the question becomes how do you trap most of your atmospheric 02? One possible solution is something like these oxygen absorbing crystals. https://www.sciencedaily.com/releases/2014/09/...


4

If you want to have the total hydrosphere being delivered on a single impact, let's first check the mass The total mass of Earth's hydrosphere is about $1.4 \cdot 10^{18}$ tonnes That means $1.4 \cdot 10^{21}$ kg. As references, Mimas has a mass of $3 \cdot 10^{19}$ kg, while Enceladus has a mass of $1.0 \cdot 10^{20}$ kg. That's a major impact. As a ...


4

Not a biologist or physicist, but the simplest answer I can think of is infrared vision. https://www.youtube.com/watch?v=Y7mROTPAVZM As seen here, it does penetrate fog to a degree, and at long distance. Yes, infrared isn't as clear as normal vision without fog, but it is probably enough of an advantage in bad conditions to be viable. I think you can ...


4

You've seen the "Great Red Storm" on Jupiter, right? You know that is a massive storm cloud with a cyclonic motion (like a Hurricane or Typhoon on Earth). This particular storm has been on going since it was first observed in 1800 and believed to be at least 350 years old and while it is shrinking overtime, suggesting it will not be persistent the storm is ...


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