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### Habitable moon of a gas giant: working out the sizes and distances

I am attempting to create fictional, stable P-Type binary system, featuring a gas giant in a stable orbit, with a habitable Earth-like moon. “Is a Jupiter-sized planet plausible in a habitable zone?” ...
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### What's the smallest reasonable natural planet or moon with Earth-like surface gravity?

We all know that equation for surface gravity is $$g = \frac{4\pi}{3} G \rho r$$ So if we want Earth-like surface gravity of $g = 9.81$, then the equation for radius is  r = \frac{3 g}{4\pi G ...
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### Can a habitable moon rely on the magnetosphere of its parent planet for radiation protection?

Science-based answers, please. Key points: the main concern is radiation protection for sustainability of human life (and accompanying plant and animal life ecosystems, whether earth-like or not). ...
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### Making a planet habitable for humanoids: The planet

The question: What characteristics are necessary for a planet to be habitable for humans? What should the generic star and planet be like? The life forms are human, so they Need to have access to ...
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### How small could an Earth-like planet be while still realistically being able to sustain human life?

I'm thinking a planet orbiting a nearby star colonized by human settlers sometime in the not near, but not too distant future. How small could a planet be while still standing in as a relatively ...
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### Making a planet habitable for humanoids: The star

The question: What characteristics are necessary for a planet to be habitable for humans? What should the generic star and planet be like? The life forms are human, so they Need to have access to ...
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### Smallest possible habitable planet? (also taking density into account)

I have seen a few similar questions but none seem to take the density of a planet into account. I'm creating a planet on which several small civilisations develop. The planet needs to have a few ...
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### What is the maximum orbital time for my moon around my planet?

I fear the math involved is beyond my capabilities on this one. I have what I consider to be more than a Layman's understanding of the physics involved, and I believe I can follow the math well ...
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### Increased Luminosity in Stars

I'm trying to construct a solar system, and I'm toying with the idea that the planet capable of sustaining life was initially outside of the habitable zone, but the star's advanced age has caused the ...
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### Habitable environment on a big moon of a gas giant lacking magnetosphere

I am trying to figure out how to make a moon (75% of Earth size) of a gas giant habitable. To give an idea of the technological level, here are technologies the colonists have access to: fully ...
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### Determining this horseshoe/co-orbital moon's possible orbital periods

I've been working on a system with a habitable moon (Moon A) for a story, and I'm now trying to populate the other moons around the parent planet. I'm considering placing one (Moon B) in a co-orbit, ...
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### Naturally making a gas giant moon habitable

Let's say that in my planetary system there is a gas giant around the size and distance from the Sun as Jupiter. I need the planet to be similar enough to earth to be able to be inhabited natural by ...
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### How do you get a thick atmosphere with less than earth-like gravity?

Basically: I want a highly viscous atmosphere but I want people to be able to walk around. I was thinking earth's gravity * 0.6 or similar. I was thinking that an atmosphere of Sulfur Hexafluoride ...
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### What are some plausible formation explanations of a non-hot "Fluffy" Gas Giant planet?

So, in my research and preparation for the question I asked immediately before this one, I was introduced to the concept of "fluffy" gas giants, gas giants with significantly lower density than would ...
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