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Here's a first-order approximation based on a fundamental limit: diffraction and angular resolution. How far someone can see of course depends on the size of the object they're looking at, because the main limitation we have is one of angular size. The issue comes down to something called the Rayleigh criterion, which is a limitation telescopes have to deal ...

7

The density profile of a planet's atmosphere arises from two laws of physics: hydrostatic equilibrium and the ideal gas law. Put together, they require that the density $\rho(z)$ be a function of the form $$\rho(z)=\rho_0e^{-z/H}$$ where $H$ is the scale height, determined by the planet's surface gravity, composition, and temperature. The scale height is ...

7

I love the concept, but don't see anything that big and made with armor that heavy (iron/steel hull as per your references to tanks and warships) being able to be held afloat with technology of the early 20th century, even in a much denser atmosphere. Using the HMS Dreadnought as my example of the early 1900s battleship, as it revolutionised battleship ...

6

With no oxygen present, a very long time. Decomposition is a process where organic material degrades, and can do this through biotic or abiotic means. (Either bacteria break it down, or it breaks down naturally.) Since there's no oxygen in this scenario, and it is in space with no direct sunlight it's wayy too cold for bacteria to break anything in the ...

5

The reason we don't see many "cosmological features" here on Earth is in large part because there aren't any near Earth. The solar system is essentially in the backwaters of the Milky Way; considering it "rural" wouldn't be wrong. Still, despite that, there are places in our solar system where more "cosmological features" are visible with the naked eye (to ...

5

This could be explained by these cosmic object being sufficiently close to the planet so enough light reaches them to render them visible during daylight hours. Not unlike how the moon is also visible during day time hours. Multiple moons could explain the multiple visible planet like objects in the sky. It would however be unlikely two actual planets ...

5

Depends, how high gravity do you mean? This study's summary https://arxiv.org/abs/1808.07417 for example suggests that 3-4 g might be doable for humans to train for. As for other life forms, they too should have no problem with that level of gravity. Of course, it would require adaptation, and prepare for human collonists to become fantasy dwarves rather ...

5

It seems very likely that Europa has a vast subsurface salt water ocean. Such an ocean would in all likelihood contain some nitrogen as dissolved gas, nitrate or ammonium salts or other more complex amides and amines. Such chemicals could be processed to release the nitrogen for use in a habitat. The exact method would depend on the form that nitrogen takes ...

5

Cant you obtain a starting supply of oxygen from water itself via electrolisis? I dont know if its the best way to obtain it, but its a way. And you still have to get the rest of the gases to get the atmosphere. Once there, you can get oxygen and food from hidroponic farms (I guess they are not consuming ONLY local fauna)

4

I would suggest that the result would be something like Venus. You might start with a planet with 1atm Earth like atmosphere at 50km altitude and a similar composition down to the surface but that would not be stable. A much deeper atmosphere would absorb more heat and at such a high pressure and oxygen concentration, organic material on the surface would ...

4

Quite simply, it would not be possible. First of all, the only reason why the Earth does not have so much carbon dioxide is because of oxygen-producing life. If your planet has developed oxygen-producing life, it should already have converted most of the CO2 into oxygen. While oxygen-producing life may have evolved only recently on your planet, other aspects ...

4

In general, I think the answer is "no"; buoyancy simply doesn't work that way, and you'd need to somehow circumvent buoyancy. What might be plausible is to have a low spot in your terrain that is completely surrounded by higher terrain (maybe a caldera?) which, for some reason, is filled with a higher density substance. If this substance is unable to escape ...

4

Somewhat to my surprise, there are, in fact, biological metabolic pathways that produce carbon monoxide. An enzyme that does this job is carbon monoxide dehydrogenase which pops up in various colours and flavours of bacteria and archaea. Usually it is used to oxidise CO into CO2 but it turns out you can run the process in reverse, given a suitable source of ...

4

You have to have air as heavy as water. If these things have an average density similar to the sea faring battle ships they look like, they could only float if the air were about as dense as water. My assumptions: These things fly like blimps, using buoyancy, not anti-gravity or jet propulsion, or helicopter blades or any other kind of active lifting ...

3

No, not without breaking the effect of gravity. Higher pressure at lower altitudes occurs because of gravity, and while this law can be temporarily disturbed by the asymetrical heating of the earth, weather systems are physics' way of constantly reverting the system back to higher pressure on bottom, lower pressure on top.

3

To keep "thicker" layers up, the atmospheric system has to expend energy. Consider dust clouds, or rain clouds. For a brief time, things that should fall to the ground can be kept in the air, but sooner or later in rains down.

3

Unlikely The principle of screws as propulsion works as good as it does in water, because water is non compressable, meaning the screw can't not press the medium outwards. With air however you loose way to much energy to air that gets forced to the side. You could of cause make a screw with a very small core relative to the diameter, but then you could ...

3

The US Navy had an intense interest in lighter than air vessels right up until the 1950's (giant blimps used as airborne radar platforms), and commissioned an all metal blimp in 1929, the ZMC-2 ZMC-2 in front of a hanger However, like all LTA craft, it works by displacement and it's relatively small size suggests that a larger envelope would rapidly reach ...

3

Spin it faster. Really fast. CoRot-7b for example is average Super-Earth at about 1.6 Earth radius (10k) and 8 Earth masses. It would be about 3G at the surface according to a gravity calculator I found. Rotation doesn't counter much gravity; the rotation the Earth counters less than a tenth of a percent of Earth's gravity at 24 hrs per rotation. However ...

3

Add some fantasy I think in order to solve this problem without changing the technology you will have to introduce some substance we don't have in our own universe (that we know of yet). I am unable to come up with any reasonable explanation that is entirely scientific, however if you introduce some new materials to make the ships lighter, assist with an ...

3

My first impression is that your two desires conflict with each other. 1) maximum temperature difference between light/dark sides and 2) gradual temperature change across a side. You may need to decide which is more important. There can be a temperature gradient, yes, but I'm assuming it would be small enough that you don't get the effect you're looking for....

3

Life organisms Earth examples and liquid water First of all within the ranges given, at temperatures lower than 150 °C and pressures greater than 10 bar water is liquid. Which also means that there is no runaway greenhouse effect under those conditions. Among the living organisms that live and reproduce in those conditions there are the following: ...

2

There are various methods out there, some more effective than others. Extract diluted oxygen. There's always air in water, its a given. You would generally extract the air shaking the water, causing the air to escape. That being said, this is not turning water into air, its just removing air that's already there. The Electrolysis Approach. Popular as a ...

2

Someone once asked Randall Munroe whether a submarine could float within Jupiter's atmosphere. His response includes the passage below. TL;DR: buoyancy depends only on density, but by that time any atmosphere is dense enough to support a ship it also has a pressure high enough to crush it. Buoyancy depends on density, not pressure. There's a point in ...

2

I took this panorama photo in the Oklahoma panhandle, one of the flattest places on Earth. It is 180 degrees (that's the same highway stretching in both directions). It was shot with an iPhone SE, whose aperture pupil is 1.86mm, smaller than what HDE226868 lists as a bound for the human pupil (therefore the human eye would do better on his limit calculations)...

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This kind of pressure inversion can happen at night over bodies of water, as the water releases the heat it stored during the day. The inverted density gradient in the atmosphere helps sound travel by reflecting it back down. I remember doing something about it at Uni 30 years ago, but I've forgotten the equations, something to do with refractive indices.

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Your solar system is moving through a carbon monoxide rich molecular cloud. https://en.wikipedia.org/wiki/Molecular_cloud There are regions of the cosmos occupied by immense clouds of molecules. There is a lot of hydrogen and second to hydrogen is carbon monoxide, followed by other molecules including methanol, ammonia and others. The Taurus Molecular ...

1

Firstly, Rayleigh scattering, which effectively redirects a small portion of light as it travels through a perfectly clean atmosphere. In a pure nitrogen atmosphere at STP, the light you get out of a regular green laser (wavelength 532nm) will have a Rayleigh scattering cross section $\sigma$ of about 5.1x10-31m2. You might expect to find about 2x1025 ...

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