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For questions about any large astronomical bodies classified as planets, and their effects on their systems.

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1answer
19 views

How would I create a planet with exaggerated aurora?

I want to create an earth-like planet with massive aurora, visible during the day, and from the equator. How would I go about doing this? Do I increase the strength of the planet's electromagnetic ...
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0answers
45 views

What is the distance between binary planets? [on hold]

What should be the distance between two Earth-like binary planets, each having its own moon? Each planet is rotating about a barycenter in a plane of their solar system and the moons are rotating ...
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2answers
98 views

Could a habitable planet with lower gravity have a thick atmosphere?

I'm designing a habitable earth-like planet that has oceans, forests and life. Now this planet is a bit larger in diameter than earth but its mass and therefore its gravity is a bit lower. This lower ...
7
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2answers
647 views

Could a planet, tidally locked with the sun, have molten rock on the side that faces the sun?

I am designing a solar system, with the first planet located very close to the parent star. This planet has become tidally locked to the star. Is it possible for to have a molten lava ocean on the ...
1
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1answer
90 views

How big does a moon have to be to have the earth locked to it?

I would like a earth-moon system like Pluto-Charon (but with earth instead of Pluto) where both will be tidally locked to each other within something like 3 billion years (before complex life appears)....
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3answers
177 views

Minimum required technology for a species to reach space?

Ok so first of all, let's imagine a civilisation on a planet. The planet has a relatively low escape velocity, say 6 km/s and maybe an atmosphere 30% - 50% the thickness of earth's atmosphere. Now ...
12
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4answers
2k views

Simulating gravity in a gravity-less universe

In my fantasy universe, there is a disc-shaped world that has a flat surface that has roughly the same atmosphere as Earth (see this); the atmosphere moves along with the world. There is no gravity in ...
10
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4answers
2k views

Will people suffer from the same diseases on other planets?

Just for curiosity, I am a diabetic and I was wondering if humans would suffer from the same ilness if they were on other planets? Does the climate on other planets help the immune system? Will there ...
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5answers
2k views

Could a moon or planet exist with “puddles” of breathable air in deep craters?

Could a moon or planet with otherwise no atmosphere maintain gas pockets in sufficiently deep craters, and could it be habitable by humans without pressure or space suits? I found this similar ...
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3answers
226 views

Is it possible for humanoid life to develop on a 1.4 G planet?

I'm writing a JRPG-inspired novel set on a planet with 1.7 Earth masses and 1.4 Gs, but is it possible for life to even develop on such a high-gravity planet in the first place? I tried scouring the ...
7
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1answer
147 views

Tidally locked dual planet system and their magnetospheres

I have two tidally locked planets of roughly equal size (about the size of Mars) orbiting each other around a barycenter equidistant between them. They complete a day-night cycle every 72 Earth hours. ...
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11answers
333 views

Why might a planet or solar system go undetected until discovered by a ship?

I have a scientific research vessel that is exploring an alien galaxy. I would like this vessel to detect and then explore a planet that was not previously known about, which means it (or potentially ...
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26answers
12k views

If a large space ship crashes on a planet, what could kill passengers without obliterating the ship?

The situation I'm considering is as follows: A large research vessel with a crew of about 100-200 attempts to land on a potentially habitable planet, but something goes wrong during the descent. A ...
0
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1answer
125 views

How can a planet have an atmosphere in a universe full of water? [closed]

Imagine a universe where the space is not empty (or almost empty) but somehow it's full of water or other liquid. How could planets still have an inhabitable atmosphere? What could make this "air ...
17
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6answers
5k views

Can a habitable planet have two separate crusts, both of which can sustain life?

Can a habitable planet have two separate crusts, both of which can sustain life? I am wondering if through the planet's creation, over time through some form of mantle cooling/erosion combination, ...
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2answers
154 views

How to travel between planets on the same star system in Sci-Fi? [closed]

We know, that to travel to another star systems, we need to use FTL for traveling. But if you need to travel to another planet in the same star system, what type of travel should be used? Is it worth ...
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3answers
83 views

Weather among the average tropical coastal regions? (I can't be more specific than this since i lack a map, I apologize) [closed]

I have a super-earth world. The surface of the world is shallower due to extra gravity, so shorter mountain ranges and less ocean depths. The world orbits a binary star system at a distance of the ...
0
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1answer
96 views

Possibility of a dyson sphere-esque structure with earth physics? [duplicate]

I have an idea for a DS-like world setting mostly set after the year 4200. The Earth was destroyed around 2500 and humanity moved from earth to an asteroid best and built a giant dyson sphere to live ...
6
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2answers
156 views

How feasible is my Exo Planet - Penumbra

My planet - let's call it Penumbra for now - exists at roughly 1.5 AU from it's sun - which was similar to Earth's - but is about a billion years older. It is 15% more massive than Earth, but nearly ...
3
votes
2answers
224 views

Could I make a planet with these parameters?

I want a planet that is twice the diameter of earth's but has very similar gravity, atmosphere, and day length. Would doubling the rotational speed of the planet meet these parameters without notable ...
7
votes
6answers
2k views

Is it easier to mine asteroids than planets if teleportation technology exists?

Inspired by comments to JBH's answer to The worlds between, the consequences of instantaneous FTL. The Premise A technology for instantaneous travel exists, making it possible to travel to any point ...
0
votes
1answer
108 views

What would the effects of extremely intense UV be on unprotected human settlers of a planet and what is the maximum level they could tolerate?

This question is kind of hard to explain succinctly, and I apologize for that. Obviously, humans experience acute effects from UV light on Earth in a matter of minutes near the equator (UV index of ...
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1answer
91 views

What is the highest and lowest comfortable average temperature on a planet?

I want to write about a planet that has a high average temperature, but low enough to be comfortable. Just because of curiosity, I would also like to know the lowest comfortable. Additional Info: ...
6
votes
2answers
100 views

Vision on Titan/Early Earth and the technicalities of a creature seeing in near infrared

I am trying to develop an alien species that could live on Titan and at first I supposed it would be easy with the species being able to use yellow, red and near-infrared wavelengths of light to see. ...
1
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0answers
70 views

Number of planets in a habitable zone with large moons [closed]

I recently had an idea, and it involved moons. Excluding gas giants, roughly what percentage of planets in the habitable zones of their stars would have large moons like Earth does, as opposed to Mars ...
0
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3answers
174 views

Feasibility of a mainly forested planet

I have a small planet with a Radius of 3,900 kilometers and a density of 8.9 g/cc. It has an extremely Earth-like climate and has been extremely volcanically and geologically active in the "recent" ...
4
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1answer
80 views

Visibility of second star in S-type system

So in my world there is a planet orbiting a star, which is in a far binary system with another star. Is there any formula to calculate when the distant star would be visible - times of year and/or day?...
28
votes
6answers
7k views

5km artificial planet, with same gravity as on Earth

So, the idea in a story is that in far far future there’s a trend that rich people, they are able to buy themselves planets. Tiny little planets with sizes 4-6 km (3-4 miles) in diameter. The company ...
10
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2answers
166 views

Dozens of Habitable Worlds in One System?

I want to know if this is physically possible. So at first I thought I was nuts. Then I started reading about Hill Radii, and googled left and right. Turns out a Hill Sphere is the region around an ...
1
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1answer
179 views

What are the minimum dimensions for planetary rings to be as visible as the moon in our night sky?

What are the minimum dimensions (length, width, height, etc.) for rings to at least be as significant (as in brightness/visibility) in the night sky as our moon? Since there are so many variables ...
7
votes
3answers
79 views

Terrestrial ectotherms outside the habitable zone

Premise We have found extremophiles of the aquatic and microscopic types here on Earth, but so far large terrestrial extremophiles are the stuff of conjecture only. This makes it somewhat challenging ...
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2answers
69 views

If the earth is sentient and can communicate with humans, shouldn't humans in general have more respect for its well-being? [closed]

Someday in the far future, when creatures are born from sentience modules that can be easily embedded into other living, non-sentient, or even non-living objects, humans became capable of ...
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votes
3answers
104 views

5x5 Biome Scale possibility?

My world has a conlang that heavily emphasizes words in 'grades' of 5. For example the words for issues are grouped as: Danger-Threat-Risk-Hazard-Situation. Usually it isn't hard to find a set of ...
7
votes
2answers
513 views

Siamese Twin Planets?

Premise I want to explore the possibility of a planet that is extremely misshapen. If we were to extrapolate what we have observed from our solar system and the extra-solar planets discovered so far, ...
10
votes
4answers
229 views

A brighter moon that's harder to see

In honour of the full moon an odd moon question for you all. The idea is to create a situation in which the inhabitants of a world believe utterly that the moon only exists at night. I'd also like to ...
6
votes
1answer
74 views

Polar Day/Night

This is my first question so any feedback is appreciated! I basically have an Earth analog that has an axial tilt of approximately 12 degrees instead of Earth's 23, and I wanted to find out how I ...
25
votes
7answers
4k views

Relative Super Powers

The origin of Superman is fairly well known. A baby is sent to a planet and gains super powers from being in the environment (technically the sun, but I believe you catch the gist). I'd like to make a ...
10
votes
4answers
2k views

Could a world exist with a distinct line of changing temperatures between the hemispheres?

I'm trying to create a world where there's an equator-like divide running along the axis(?) of the planet and the two hemispheres are perpetually different in terms of temperature. Basically, I want ...
6
votes
2answers
130 views

Multiple moons but only one of them is tidally locked to its planet?

A habitable planet with multiple moons, only one of which is tidally locked to the planet: is this general scenario possible? I understand that tidal locking takes a very long time to happen. So ...
39
votes
6answers
7k views

Planet wide seasons: Possible?

I was reading a World Anvil article which has a world that experiences world wide seasonal changes. Specifically quoting the article, During the month of Frimense, the Frostkin thrive, as the ...
4
votes
3answers
113 views

What natural factors could possibly push a species of eusocial insects to become intelligent?

So, I am working on a species called the Vosians, who hail from the planet Vos. They are a species of eusocial insectoids, much like Earth ants. Biology The Vosians are about 3 feet tall, or 0.9 ...
2
votes
2answers
82 views

Albedo of a planet like Crait

If a planet like Crait existed and was covered by (mostly) white sand, what would its average albedo be? Crait is a planet from Star Wars that has a thin layer of white salt on its surface.
6
votes
1answer
274 views

I've determined how many planets my solar system could plausibly have. How do I figure out what kind of planets they are?

The 12 planets in my solar system orbit the G-type star of Nemo. It's about nine-tenths of the size of the sun, and has a stellar luminosity of 0.67 L☉, a diameter of 1.28 million kilometres, a ...
3
votes
2answers
113 views

How many planets should I have in my planetary system?

I am building a planetary system, but I always thought how many planets should I have in this system. When you look at our solar system there are 8 planets. Other exoplanetary systems can have up to ...
18
votes
7answers
3k views

How do I maximize a planet's wave height (on average)?

Premise I am in the formation phase of a fictional world. I would like one of its notable characteristics to be extremely large waves. On Earth, most of our large waves are triggered by earthquakes, ...
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3answers
149 views

Would this type of atmosphere be suitable for human life?

I've been trying to create a Earth-like planet but I'm not sure if my planet's atmosphere is breathable. (It's mostly the amount of helium I'm worried about). I've tried to make it Earth-like while ...
1
vote
1answer
95 views

How massive can a terrestrial planet be and still be habitable? Will its space civilization have problems due to its escape velocity? [duplicate]

The star is Sun-sized and my planet will be more massive than Earth. How massive can my planet be and still be habitable. This is without its internal heat being a problem leading to its becoming a ...
2
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2answers
188 views

What would happen to a planet after a quarter of it had been blown up?

An alien species has created a weapon. The alien stands on a planet, points the weapon at the ground, and pushes a button. A large amount of matter condenses itself into a mass, creating a huge hole ...
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votes
4answers
393 views

Can this planet exist, within our understanding of science?

Can a rocky planet have these qualities and exist: half of earth's gravity 4/5 earth radius a magnetic field capable of retaining an atmosphere a slightly slower rotation than earth can sustain ...
2
votes
1answer
114 views

How bright does this planet look from its neighboring planet?

I have two planets that share an orbit around a pair of stars at a distance of 2.05 Earth-AU from the Barycenter of those two stars. (I can provide more details about the two stars, if needed) Using ...