All Questions
205 questions
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How long would an eclipse last on an Earth-like moon [duplicate]
I’m creating an earth-like moon that orbits a gas giant planet the size of Jupiter. The planet orbits its star at the same distance mars orbits the sun and it takes the moon 295 days to orbit its ...
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5
votes
5
answers
1k
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On a planet with 6 moons, how often would all 6 be full at the same time? [closed]
The cycles/orbital periods of the moons are 12, 20, 20, 24, 32, and 38 days. How often/after how many days would all 6 be full at once?
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2
votes
2
answers
142
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Would it be possible for a somewhat distant bianary star system to have a planet orbiting their barycenter within both their orbits?
There are 2 stars in a binary system, 268 AU apart from each other. Both are about 1 solar mass.
Would it be possible for some planet to be orbiting their barycenter (the center mass of both starts),...
- 5,163
1
vote
2
answers
363
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I have a world with two moons, and I was wondering how often they would both be full at the same time
As I said in the title, I have a world with two moons. One has an orbital period of 17 days Earth days (Moon 1) while the other has an orbital period of 57 Earth days (Moon 2) and the planet they are ...
3
votes
2
answers
147
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How to calculate the Draconic month on a fictional world
I am working on a world and want to be able to find out when Eclipses occur, and I found you need to know the Draconic Month, I think I have everything I need to find it, I have the inclination to the ...
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16
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3
answers
5k
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What is the largest fraction of Earth's sky that an astronomical object could take up (visually) before ripping Earth or itself apart?
I know the Roche limit limits how close another planet could get to Earth. Closer than that limit, and either it breaks apart or Earth breaks apart.
I don't care what size it is, if it's a super-...
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3
votes
2
answers
317
views
How do I figure out where a moon is in the sky at a given time and place?
I use this planetarium tool to see the position of the Moon to check I have it in the right place for a given place and time, for my non-Earth plant. I'm considering having another moon. How would I ...
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2
votes
1
answer
158
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Could one moon appear to always follow/lead another in the sky?
Is there any way a second moon would appear to hang out near the closer one in the sky? For example always appearing either ahead of or behind throughout the year, or even alternating between those ...
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3
votes
2
answers
331
views
Could Moon Phases work in a Concave Hollow-Earth?
I'm trying to wrap my head around how phases of the moon(s) would operate in a hollow earth. For reference, I am picturing a situation like this:
In this system, the center of the hollow earth has a ...
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2
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3
answers
403
views
How would a planet's surface be younger than the planet itself? [closed]
Europa, one of Jupiter's moons, is 4.5 billion years old (like Earth.) However, its surface is only 20-180 million years old. What could lead to a planet/moon's surface being younger than the planet/...
1
vote
0
answers
114
views
How can an Earth-like planet support two moons of different sizes [closed]
In my world, I need to have two moons orbiting an Earth-like planet. I need the extreme tides as they play a big part for a cultural detail. The first moon should be roughly the size of our own moon, ...
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2
votes
2
answers
247
views
What astronomical situation could account for the PERCEPTION of a very erratic day / night cycle for a planetbound population with limited science?
I would like to create a world that is at a roughly medieval level of scientific understanding and which - as far as it appears to the inhabitants of that world - has a highly erratic day and night ...
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0
votes
0
answers
147
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Can there be habitable moons despite heavy changes in axial tilt of their mother body?
Ok so i created a gas giant with 10 Jupiter masses and like 9 moons between 0.8 and 1.5 earth masses. All exept the most distanced of those moons are tidally locked to the gas giant and their axial ...
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3
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1
answer
177
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Can a tidally locked planet with two counter-orbit moons exist for at least 100,000 years?
I believe it is true (correct me if I'm wrong) that a planet with a significant moon such as ours cannot be tidally locked. The orbit of the moon would continue the rotation of the planet and must, ...
- 132k
1
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2
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159
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Reverse engineering the Hill Sphere?
I'm wondering if anyone has run into the issue of "I know the general idea of how big my moon is but not the parent planet" and how to sort of reverse engineer finding out the mass/radius of ...
2
votes
1
answer
432
views
How could an Earthlike planet have two moons, one similar to the Earth's moon and the other primarily composed of carbon? [closed]
I am building an Earthlike planet that possesses two moons, one similar to the Earth's in terms of chemical composition and one primarily composed of carbon. How could these two moons form? Which moon ...
- 4,454
0
votes
2
answers
649
views
Space Elevator for Ganymede
My settlement on Jupiter's moon Ganymede is to get a space elevator. Unfortunately, I am completely overwhelmed with the math: How long would the cable have to be to the stationary anchor point in ...
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-2
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2
answers
235
views
Habitable moon and hycean world [closed]
A hycean world is a cross between a rocky planet and a gas giant. Think an ocean world with an atmosphere full of hydrogen.
Assuming it is in the habitable zone of its star, could a habitable moon, ...
- 3,202
1
vote
2
answers
185
views
What would happen if a Europa-like moon "thawed"? [closed]
I have a planet and moon system orbiting a high mass star, something like a type A main sequence. Everything is only a short two billion years old, but the star is already starting to expand, warming ...
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6
votes
1
answer
344
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On the tidal heating of a moon. What is the second Love number?
Years ago it was asked here how to calculate the tidal heating of a moon orbiting another body with a simple equation. The answer is very detailed. They explain the equation, its shortcomings, the ...
3
votes
1
answer
122
views
Geological activity and of superearth - cannonball moon system
I understand that this situation is hypothetical -- I just need a piece of advice to make it more realistic.
In my story, there is a superearth of 4,5 Earth masses and 1,35 Earth's radius, rotating ...
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12
votes
1
answer
2k
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How old must The Moon be?
Some time ago, aliens placed the Moon around Earth with every intent to deceive us about its authenticity, except for the glaring synchronization that allows for total solar eclipses, as something ...
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3
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1
answer
242
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How stable would partial planetary rings be on Lagrange points?
Context
There's a comparison to what I'm talking about on a larger scale: Jupiter's got its Trojans and Greeks, and Earth does have them too. Those are more or less loose and sparse groups of ...
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11
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2
answers
5k
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Could a planet have 1/2 the Earth’s mass but 1 g surface gravity?
So, we have a captured planet/moon orbiting a gas giant in the habitable zone. It is akin to prehistoric Mars, its geological activity having been maintained by constant tidal flexing from the gas ...
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5
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3
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2k
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White-hot tungsten moon emitting heat and light to make my world habitable
Never mind how the tungsten sphere formed. That's part of my pet projects, and I will deal with the question of how a nearly pure sphere of tungsten the diameter of the moon formed in space later.
So, ...
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2
votes
2
answers
263
views
Can planet with three moons, have one tidal-locked both on rotation and revolution?
I'm a new D&D 5E Dungeon Master and I've found out recently about tidal locking.
For the first RPG setting I'm preparing with a friend, the planet the players will be on has 3 moons. Me and ...
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1
vote
1
answer
66
views
Could a substantial atmosphere protect a large moon from radiation belts like those seen in Jupiter's magnetosphere?
I'm imagining a moon with a mass of 0.25M (so 10 times larger than Ganymede), in Ganymede's position orbiting a gas giant like Jupiter. Maybe the atmosphere is anywhere from 0.1 - 1 bar. Would the ...
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0
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2
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207
views
Help me create a more believable artificial planet
Ok, I noticed some very intelligent answers on this platform and I would love your input on the planet for my book trilogy. I have been working on the blueprint, story structure, and characters for ...
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1
vote
1
answer
135
views
Tides on a planet with 5 moons? [duplicate]
What would be the effects on an earth-like planet with 5 moons, one the size of Earth's moon and the others approximately 1/10th its size?
How massive would the tides be when they align?
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5
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1
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239
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Daily eclipses for a moon orbiting a gas giant?
I've dug into the idea of a habitable moon getting daily eclipses due to its gas giant getting in the way of the sun; but most examples I've found specify a tidally locked moon. I'm no astrophysicist ...
0
votes
1
answer
176
views
Various eclipses in a P-type binary star system?
Trying to make a world with a P-type binary star system, with a habitable planet orbiting around them, and one moon orbiting said planet. I am terrible with physics so I've been wondering if any of ...
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5
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5
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207
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Can a Moon Shoot Spores?
I'm currently working on a world for a fantasy novel. For the sake of this discussion, we can assume it's low to no magic at all, and has no higher-intelligence interference, such as creator races, ...
4
votes
2
answers
114
views
What would happen on a binary planet if they captured a new moon into orbit?
I've been working on a world where the origin of the magic system is a catastrophic event that ripped the surface of the planet apart allowing magical energy from beneath the crust to escape to the ...
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3
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3
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1k
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Could a planet without an orbiting moon still be habitable to human life in at least one small pocket? [closed]
No moon likely means no tides. Does this make a planet half water, half land, or similar divisions? Do freshwater and saltwater have separation? Or would it just be a planet like ours, with delineated ...
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4
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4
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377
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What are the odds of a binary solar eclipse?
I'm currently creating my own binary star system which includes a circumbinary planet that has two moons. For simplicity's sake, the stars, planet, and moons are comparable in size to our own Sun, ...
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4
votes
1
answer
279
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Is terraforming of Europa going to make Jovian system much more dangerous?
I’ve terraformed Europa. The now oceanic moon with floating islands was given thick atmosphere (pressure, thickness and composition to be established later, but I’m aiming at something thick, murky ...
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4
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3
answers
205
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Is this method of “burial” possible?
Now that colonization of Mars and The Moon is starting to pick up, lots more people will start dying. LifeHarbor Burials™ says that they will provide a way to dispose of the dead for free.
They claim ...
- 2,356
5
votes
5
answers
314
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Multiple moons with little effect on the planet
In general, I'm considering having my planet have multiple moons but at different points in its history, the count of the moons increase or decreases (like every few thousand years a moon comes or ...
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4
votes
5
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280
views
Endless global night.. but an agreeable climate, how come?
How would my planet develop an acceptable climate, without a sun ?
There is no (visible) sun, but the climate permits STP, and there are 1 or more luminous, rocky moons providing some light.
Perhaps ...
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2
votes
1
answer
224
views
More Moons = Brighter Nights?
Now, firstly, I understand that the moon reflects a portion of sunlight onto the night's surface; So if a planet had multiple moons--say two or three, how would the additional celestial mirrors affect ...
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4
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3
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270
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Is this habitable moon formation scenario plausible?
My and my teams' works take place on a moon orbiting as giant about 3 times the mass of jupiter (possessing also a massive moon system) in a solar system with an F-star and be either the first, third ...
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3
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1
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267
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Habitability of my world
For a big narrative project of mine I and my team developed an habitable moon that revolves around a gas giant in a star system with an F-star. I wanted to know what you think about it and if you ...
- 1,444
4
votes
1
answer
197
views
How plausible is this planetary system with binary stars?
In my world, I have a binary S-type Solar System of Star-A and Star-B with these properties:
Star-A:
Luminosity: 0.86822 Sol / Mass: 0.98097 Sol / Radius: 0.91958 Sol / Radius of Hill Sphere: ~37.218 ...
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16
votes
17
answers
5k
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What would cause a moon to become much brighter only a few times a year?
I initially wanted to create a culture that used tides to tell the seasons, I'm sure I still can, but a question on here (I can no longer find it) made me wonder if I could set up a world where one of ...
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4
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2
answers
233
views
How Habitable are these Planets?
For the book I'm writing for my world, Damarian, the villains of the series (The NUSA, America's descendant) are banished off Damarian (Spoilers). The banished are shipped off, but 3 groups formed, ...
- 1,147
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votes
5
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468
views
Is there a way for a permanent Lunar eclipse, or another Object to always be in Earth's shadow?
I have a question regarding worldbuilding and haven't found a question like this yet, so I created an account and hope that someone can answer it :D
As a starting point, imagine our real-life Sun, ...
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3
votes
1
answer
172
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Damarian's Parameters: What are they?
For Damarian, I have its system starting to be worked out, and I even have the basics of Checuti and how Damarian orbits around its mother planet. (Link to my first question about this system is ...
- 1,147
1
vote
1
answer
242
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How long should a Life-Harboring Mega-Moon's orbit around its Mother Planet be?
Damarian, the world I'm building, is the largest moon of its gas giant planet, Checuti. Damarian's diameter is 19,113 km, but its gravity is nearly the same as Earth's (It' largely made out of a ...
- 1,147
7
votes
4
answers
541
views
Would it be possible to have an earth-sized planet have much larger tides while remaining habitable?
I want a planet with roughly the same mass and volume of earth to have tides on a much larger scale than earth, enough that the coast would be extended for at least several hundred feet at low tide in ...
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1
vote
2
answers
266
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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) ...
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