Questions tagged [planets]

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

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11
votes
6answers
1k views

Possible reef world?

Piggybacking off this question: Shallow sea world - plausable geology? what would we need to have a world covered in reef? An entire world of this: If I understood them correctly the previous ...
4
votes
1answer
84 views

What would it look like if an artificial atmosphere began to disappear?

In my SciFi-Magic RPG campaign, the main characters are on Mars, which has been converted to a prison planet. A large device, drilled into the north and south poles, reaching into the core, heating ...
2
votes
2answers
92 views

If visible light from the sun stopped hitting the earth but the sun still existed, how would this affect the earth?

The sun produces light, heat, and other things. If the visible spectrum of light from the sun stopped hitting the earth but only the light directly from the sun, so moonlight and if heat can be ...
11
votes
3answers
843 views

What are the atmospheric/planetary effects of having no solar wind?

Suppose we have an earthlike world orbiting an artificial star which produces light but no solar wind. I would like to understand the implications that a lack of solar wind would have for the planet. (...
6
votes
3answers
587 views

How can I give my habitable planet argon in its atmosphere?

I want my planet's atmosphere to have roughly 10% argon so that its inhabitants can easily use it to color their lights purple. But I'm not sure how to explain the cause of this high argon content. ...
5
votes
2answers
480 views

Tidally Locked Planet, Weather

If the polar cap of a tidally locked planet was all ocean, what weather patterns would emerge? The ocean couldn’t be half frozen/half boiling, right? I need a weather pattern so the planet isn’t just ...
10
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3answers
622 views

Placing a planet on the famous Escape Velocity Graph

If I'm understanding the chart correctly, in order for a planet with lower gravity than Earth (smaller than Earth), but with decent magnetosphere, to hold on to an atmosphere with oxygen, and water on ...
3
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4answers
2k views

Probability of a spaceship stumbling upon a random planet?

In an intergalactic federation, space ships are extremely common. They run supply routes, defend planetary bases, and transport colonists to new worlds. To aid in these adventures, most ships would ...
1
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1answer
82 views

Predict The Orbital Eccentricity Of A Planet In A Circumbinary Orbit

Okay, I have a planet smaller than Earth that has a mean orbital radius of .9 AU, and it orbits twin suns. The larger sun has a mass of 1.15 solar masses, and the smaller sun has an mass of .45 solar ...
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0answers
122 views

Is This Desert Planet Realistic?

Okay, I have a desert planet that orbits an M0 star and an G0 star at an circumbinary orbital radius of .9 AU from the shared center of gravity of its twin suns. It’s tilted on its axis by 23.5 ...
1
vote
1answer
195 views

Changes to water worlds to make them habitable

What changes/additions/deletions, large or small, minimum handwavium allowed, would be needed to make suspected water covered exo-planets such as Gliese 1214 b, Kepler-22b, Kepler-62e, and Kepler-62f, ...
25
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8answers
3k views

Initial conditions for a fluorine hellscape

I'm curious what it would take to get a planet with so much free fluorine that you can have an atmosphere of predominantly or purely fluorine. I realize how improbable a planet like this is, so I'm ...
14
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12answers
624 views

How to dry an ocean planet and turn it into a salty desert?

I have a planet covered with a large shallow ocean, which extends over most of its surface. I want to turn this planet into a great desert, specifically a salty desert (the salts of this desert are a ...
3
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6answers
143 views

How do I stop my near future city state from flying past a certain height and distance or sending up sats, but keep radio communications intact [closed]

A near future large city state is surrounded by a far more massive forest that is semi sentient. How do I stop them from sending up satellites, or sending up weather balloons high enough so that they ...
2
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3answers
147 views

Telepathic octopi influencing other species [closed]

Let's imagine humans are somehow controlled by a smart telepathic species that make themselves invisible to them, say everyone has an octopi on their head and are unaware of it. Every time the ...
8
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6answers
2k views

Reasons for insanely huge precious metal deposits?

In my book series, there is this extremely rich Earthlike planet called Aurea whose claim to fame is supplying the vast majority of the galaxy’s precious metals (gold and silver for the purposes of ...
5
votes
4answers
318 views

How would a torus planet's magnetic field work?

Simply put as the title says. I'm going to handwave that the planet is held together with magic, but I want to know how a magnetic field would work on a toroidal planet- assuming such is even possible....
1
vote
2answers
167 views

Is This Living Planet Plausible?

My idea is an planet that is one living organism wrapped all around an rocky foundation. It orbits an sun of one solar mass, and has an Earthlike radius. Its albedo is about 20%, so it gets 1098.4 W/m^...
5
votes
1answer
143 views

What substance would make a good lava ocean?

I'm starting work on some fictional star systems, and I want to create a planet that has lava oceans. I found an excel spreadsheet a while back that does calculations for stars and planets, and based ...
11
votes
4answers
2k views

What are the requirements for an atmosphere retaining moon with a stable orbit around an Earth-like planet with non-destructive tidal forces?

For story writing purposes I would like a realistic setup where there is a planet with close to earth conditions in terms of gravity, relative position to the sun etc. However I aim to have a much ...
1
vote
1answer
53 views

Rotating ice lake of high molar hydrochloric acid

Say I have a rocky airless world with size and density to produce two gees orbiting around an old dim star. Could I have a round(ish) lake with a high molar hydrochloric acid ice? It could be ...
2
votes
1answer
132 views

How Small Can a Planet be with 1G Gravity and Tectonics?

Without resorting to solid osmium inner cores that we couldn't give an origin story for, what's a cosmologically plausible lower bound of a planet's radius that also maintains 1G gravity and the sort ...
1
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0answers
46 views

What color can the sky be, and yet still be a human-breathable atmosphere? [duplicate]

With a star similar to our own Sol, what other gas or gases could replace Nitrogen, while allowing O2 to mix properly, yet have say, a sky that was green or red? Sulfurhexaflouride is out as it is too ...
3
votes
3answers
112 views

How would the reflection of sunlight change the day / night cycle of a binary planet system?

I am thinking of setting a story in a binary planet system, but am unsure what mechanics would be at play in regards to the reflection of light off of one planet and the day/night cycle. In this story,...
12
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3answers
755 views

What is the largest possible appearance of a celestial body in the sky?

In SciFi Art we often see planets/moons/stars fill enormous amounts of the visible sky. I'm wondering what the theoretical limit for this is realistically, since there are maxima for the possible size ...
2
votes
1answer
109 views

Climate of a Planet in a Binary Star System

Would the climate of a planet in a binary star system consisting of a K star and a G star be affected by the binary system? By this I mean, does having two stars at the center of a solar system affect ...
2
votes
2answers
180 views

Is it plausible for a planet to have a face constantly sunlit while the other is constantly moonlit, with the sun/moonlit territories never changing?

I'm writing a sci-fi & fantasy novel, I won't get into details, but in essence it's set on a fantasy planet that orbits around a sun, and has a moon. The basic premise (that I'm hoping for anyway) ...
6
votes
1answer
237 views

Can a fast planetary rotation create a planet with an equatorial continent, preferably with very high mountains and two polar oceans?

I’m trying to create a planet with two small polar oceans with equatorial supercontinent in the middle. The land is in turn divided in two by high mountains that act as barrier and a source of water ...
3
votes
5answers
118 views

Could a planet form from the remnants of a star and its solar system?

This is just a simple question, and I haven't thought all that well on it, but I think in terms of sci-fi and fantasy less tied to probable scenarios this could be quite possible. Imagine a free-...
6
votes
1answer
129 views

Oceans of breathable liquid

I want to create a locale (hopefully a whole planet?), where the ocean is breathable. I was looking at perfluorocarbons, so the liquid part is at least possible(?) Is there any way to create a world ...
1
vote
1answer
188 views

Can a planet hypothetically have two atmospheres with an ocean in between?

I want my hypothetical planet to have a sort of ocean to filter out radiation, but density is problematic. There would have to be an outer atmosphere, and then some form of ocean-like liquid that is ...
13
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6answers
2k views

Can a planet move itself?

Most questions in this vein seem to center around the inhabitants of a planet moving it. I have a significantly different spin on this idea, though. So, you're a big ball of rock spinning around a ...
7
votes
3answers
683 views

Plausibility of an atmosphere on the furthermost planet of a solar system

Atmospheres like Earth's or Mars would freeze and precipitate towards the surface if the planets were to be moved very far away from the Sun, since the light that reaches that far is incredibly dim ...
0
votes
1answer
67 views

Scanning for Resources and Mapping a Rogue Planet

EDIT: Thanks to Starfish Prime's answer to this it looks like the atmospheric ice would only be ~16m thick, and the water vapor is a rounding error. I have adjusted the layering to account for their ...
-5
votes
1answer
89 views

What does it take to vaporize (Or possibly put a hole through) a planet? (G.R.B.C. Part 2/2) [closed]

Now, like, 40 minutes ago, I asked a question concerning a possible Gamma Ray Burst Cannon. And I was disappointed, to say the least, with the answers. So, it's time for Gamma Ray Burst Two: Electric ...
8
votes
3answers
722 views

What could be the largest geosynchronous moon?

If we consider a planet with the same characteristics as the earth, (diameter, mass, rotation period) what would be the maximum possible diameter of a moon on a geosynchronous orbit? Considering the ...
4
votes
3answers
137 views

Why would humans fight a planet full of monsters? [closed]

So in my world a portal suddenly opened on a field. The portal leads to a planet full of monsters. Why would the people in my world attack and defeat the evil planet. What resources would there have ...
13
votes
5answers
3k views

Could We See a Lagrange Giant in the Sky?

The "Lagrange giant" in the title refers to a gas giant that orbits its star in the same distance as Earth does. The alternative description is "Trojan planet" or, to be most ...
2
votes
1answer
107 views

What color would plants be on a hot spring planet? [duplicate]

I had an idea for an alien world I want to set a story on and if this question proves popular I might ask other questions regarding this world. The world in question is an earth like moon orbiting a ...
2
votes
1answer
88 views

Rocheworlds mass

Suppose you've got two tidally-locked planets, each one orbiting its own red dwarf. With two red dwarfs to hold the planets, could the planets get close enough to share atmospheres? And how would you ...
6
votes
3answers
243 views

Low gravity planet, giant creatures?

I want to create a planet that has: Low gravity. Giant creatures (not quite Godzilla sized, but bigger than Dinosaurs). Human explorers should be able to jump incredibly high there, maybe even fly/...
6
votes
2answers
218 views

What does a gas giant close to a red dwarf look like?

In my setting, there's a gas giant orbiting in the habitable zone of a red dwarf (for specificity, its radius is about half Jupiter's, and it's 0.35 AU from 61 Cygni B. Ignore the effect of the other ...
6
votes
3answers
682 views

Could a Titan-like moon orbit a terrestrial planet?

Could a terrestrial planet (1x diameter and mass up to 1.5x diameter and mass) hold a Titan-like (dense atmosphere, relatively large size, weather) realistically in its orbit? If not, how large would ...
10
votes
19answers
4k views

How Do I Keep the Population of an Ecumenopolis Reasonable?

In the galaxy I'm worldbuilding for my science-fantasy series, by far the most important planet in the galaxy is an ecumenopolis called Ishga. What I had in mind for this planet is something ...
3
votes
5answers
279 views

Binary planets system day/night cycle

My story has two planets separated by ~35,000 miles of empty space- tidally locked through a magic "planetary anchor" light rope that connects the two planets and keeps them at that exact ...
-1
votes
1answer
44 views

What Kinds of Gas Giants Would Work Best in Orbiting an Orange-Dwarf Binary?

The term "gas giant" is, surprisingly, not uniform. It turns out that there are far more to the gas giants than Jovian or Saturnian. I won't list you all of them, just those that I find ...
6
votes
2answers
209 views

Influence of an inner gas giant over a solar system

I'm designing a solar system with three planets in its hot zone, two in its cold zone and three in its habitable zone. All of the planets are rocky worlds of various sizes, except for the middle world ...
7
votes
6answers
3k views

How Big Can a Habitable Planet Get Before Its Gravity is More Than 0.8 m/s² above Earth's 9.81 m/s²?

This is NOT a repeat of this question. I am NOT looking to see the smallest planet possible that has less gravity than Earth. I am looking for how big a perfectly habitable planet (Habitable meaning ...
2
votes
3answers
189 views

What if a moon orbits far away and extremely fast?

Imagine an Earth-massed moon orbiting around a Saturn-massed planet in a period of 28 days. This calculation tells me that is possible if the moon is 1.8 million km away. If so, the moon must be ...
4
votes
1answer
180 views

Acute Radiation Poisoning on Io

I am trying to develop story about the colonization of Jupiter's moons. Io is assumed to have a background radiation of roughly 3600 dayrems. I would guess that other factors such as lunar ...

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