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Questions tagged [moons]

For questions pertaining to natural satellites, such as our own Moon.

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Moon Day Lengths

In a nutshell, I'm trying to build a world with erratic day/night cycles. To get the erratic days, I'm working with a habitable moon. It takes 3 full earth days (72 hours) for the habitable moon to ...
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Is a horseshoe/co-orbital moon a good choice for my system

I've been working on a habitable moon system (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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How can a moon have an ever-changing face?

Imagine an inhabitated planet like ours with a moon of the same projected size in the sky. The moon has visible structures of colors or darker and lighter areas. Every evening when the moon gets ...
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3answers
188 views

How does having 3 moons change a planet?

I'm working on a story that takes place on a world that has 3 moons. At least 2 of the moons are the same size. They align extremely rarely. Otherwise, it's an earth-like planet. There is one ...
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1answer
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Co-orbits and Tides

I've seen many questions about tides and tidal variations on a wide variety of interesting single star, multi star, single planet, binary planet, single moon, multiple moon, and even ring system ...
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1answer
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Could a Moon have its own “Rings”, like Saturn's, without the Host Planet having them?

I'm currently fleshing out a sci-fi universe and always looking for fun new locales to populate it with, and I saw this phenomenon in a video game I've been playing recently, and it made me curious... ...
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How deep must be a pit on the moon to hold atmosphere at 1ATM on the bottom

In my world I would like to create a pit on the Moon filled with air. How deep would the pit need to be to get 1 ATM of pressure Could the pit maintain the air or would it be lost to space? If it ...
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Does my plot point centered around eclipses make sense?

My main antagonist is an infant Great One that's been imprisoned below the Moon's surface and I want its influence and physical form to have a weakness to direct sunlight which, I think, gives me a ...
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Time in relation to life in the Jovian System

I'd just like to preface this with the fact that I'm super new and I apologise if this has been discussed in some way previously (I have looked at similar topics but they haven't quite given me the ...
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105 views

Anchoring a Deimos base

Some astronauts have just arrived in Mars orbit! They're fixing to set up a small refueling station/outpost on Deimos. One problem, how might they keep their small habitat and associated structures ...
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3answers
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Gravitational anomaly (Mascons) creating water-hills

A scenario in the far future -- The moon has been successfully terraformed. All problems have been worked-out, from flinging volatiles into collision course with the moon, up to creating and retaining ...
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What would be the mathematical formula to figure out a person's weight on a world bigger or smaller than Earth?

Okay, trying to figure out this math guys! This may be simple math to some of you, but not me!!! I googled various ways of asking this question and got some good results, but I'm looking for a simple ...
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Would gas giants work as waste disposal sites?

In my novel, the many moons of Jupiter and Saturn have been colonized, but I'm running into some logistical problems - namely, waste disposal. My first instinct was to dump it on-moon; while this is ...
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1answer
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Can giant planets in the habitable zone have rocky moons?

My question is in the context of a fictional super-Neptune that lies in the habitable zone of its host star system. Giant planets only form beyond the Frost Line of their protoplanetary disk, and ...
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13answers
4k views

Always a full Moon for the Emperor - Can this be achieved with solar panels and LEDs?

The Emperor of the World wants there always to be a full moon. His Scientific Advisor (the SA) comes up with a plan. He plans to cost out the venture, hand it over to the Keeper of the Treasury who ...
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6answers
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Would a Moon made of water pose a threat to Earth during eclipses?

Is a moon made entirely of water possible? Could a planet made completely of water exist? I was inspired by the above questions to ask the following: Assume that our current Moon is replaced ...
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6answers
888 views

How can spacecraft manufactured on the moon be powered?

Background: The moon has been selected as the base for human space exploration. Rather than ship tonnes of material out of earth's gravity well, interplanetary space-craft and space stations will be ...
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4answers
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Moon take off without rockets

Take-off in a craft with rockets allows a gentle acceleration that doesn't kill the occupants. Given that the Moon has no atmosphere: Is there any current technology that would allow safe takeoff ...
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2answers
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Could the TRAPPIST-1 planets have moons?

The TRAPPIST-1 planets are all very close to each other and thus are subjected to strong gravitational forces amongst each other and to the red dwarf they're orbiting. Would it be possible for them to ...
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1answer
255 views

Is there a relationship between apparent moon size and orbital distance around an earth-analogue?

I would like to give my imaginary earth-analogue planet multiple (natural) moons. Is the orbital period of such moons at all related to their size (or apparent size)? In other words, am I free to ...
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1answer
96 views

Could this moon of a gas giant orbiting a neutron star support life?

Making the following assumptions: 1. The three moons of the Gas Giant are safe enough distances from and massive enough not to pull each other apart or send themselves careening into the void. 2. ...
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How would an extra moon affect the tides? [duplicate]

In my world, I'm planning to add a second moon which would be positioned closely to the first. I was wondering what effect would that have on the tides?
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Feasible star + planet + moon combo? Did I miss anything that makes this system wildly unstable or otherwise impossible?

Here's what I've come up with: The star: A main sequence star, roughly a sol analogue Younger than Sol (say 3-3.5 billion years old) roughly the same starting mass as Sol, but has had less time to ...
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2answers
133 views

Earth Orbit Extreme Change

So recently I got slated for missing some glaring obvious flaws in my story on here, which I really do appreciate. I'm approaching the question from a different angle though, in two parts. What ...
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1answer
101 views

Earth Exploded, Orbiting and double moons

I have a scenario which I am too poorly knowledgeable to address, I'm hoping for some expert input. I'm currently writing a novel, in which a large section of Russia/EU continents were blown up in a ...
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1answer
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Can Europan ice cracks sustain complex ecosystems?

Europa's surface is marred with huge, curved cracks, called lineae, which may - depending on the thickness of its icy crust - expose the subsurface ocean to sunlight. Pictures like the one above (...
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1answer
121 views

How would the transfer of mass from the Moon to Earth change the rotation, orbit and speed of the Moon and Earth?

I've read the creation of dams in Earth can change the speed of rotation of the planet because they reallocate the mass over the planet. Let's suppose humans find a valuable mineral in the Moon and ...
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3answers
329 views

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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1answer
627 views

Massive tides and resources

Assuming a situation similar to this, where the moon causes slower but massive tides that slowly encircle the globe. Would the poles be constantly underwater or not underwater (like A or B below)?: ...
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2answers
471 views

What would happen if a little less than half of the moon crashed into the Atlantic ocean? [duplicate]

Let's say an asteroid hit the moon and broke it in half. One half remains where the moon usually is relative to Earth, and the other half is flung at Earth near the equator, in the Atlantic ocean. ...
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3answers
174 views

Is this planetary moon's calendar possible?

I'm attempting to create a world that has very brutal, hard swinging weather and environments, leaving much of the planet desert-like. The world I've designed is a moon of a gas giant. The Parent ...
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1answer
181 views

What kind of Gas Giant has a “safe zone” between the radiation from a star and the radiation from a gas giant planet?

This is a progression from my first question, here (if this is too similar to my original question, please let me know of a better way to address this, as I am not getting the answers I need on that ...
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Characteristics of a habitable satellite planet [closed]

In Habitable Planets for Man, Stephen Dole establishes that a satellite planet in orbit around a massive gas giant, (like Jupiter's Titan, I guess) would be habitable for humans. What would it be ...
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How can Ganymede have an Earth-like gravity without us having realized it?

Imagine a small primitive humanoid civilization that developed independently in caves under the surface of Ganymede. We can assume there's enough light that filters through the crystalline surface to ...
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1answer
275 views

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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1answer
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If Earth's Moon Were Ganymede-Like, Part I: Rotation

I know that in the past I posted questions on if specific bodies larger than the moon--Mars in one and Titan in another--but this series deals with questions regarding Earth's effects by a natural ...
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1answer
174 views

Geostationary moon

My planet is very Earth-like with a day length of 26.87h. The moon has a radius of about 1550km, a mass of $5.2\times10^{22}$ kg and orbit 45500 km from the center of planet. My scenario is that the ...
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3answers
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Could I use a series of magnetic asteroids to create a magnetic field for mars?

If I push a couple of magnetic asteroids into mars gravitational field, could they form an interlocking series of magnetic fields able to protect mars from solar winds? Size limits for asteroids is ...
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5answers
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Why did US government hide the discovery of an ancient civilisation on the moon? [closed]

July 20, 1969, Neil Armstrong sets his foot on the moon surface. He declares : "That's one small step for [a] man, one giant leap for mankind". But what history books don't mention is that, as he ...
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8answers
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How to explain life on a moon orbiting a non-habitable planet

For story purposes, I am building a world where all life exists on the moon of a non-habitable planet (the moon is not tidally locked). How can I explain this in a convincing and mostly scientific way?...
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1answer
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Is it possible an ice line from pole to pole in a tidally locked Earth-like moon?

I am aware that there are a lot of answers explaining the fundamentals of a tidally locked "Earth-like" moon around a giant gas planet. For example this one: Habitable moon of a gas giant: working out ...
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3answers
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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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Conditions for an Ice Covered Moon to survive around a Terrestrial Planet

In my fictional setting, the planet that people live on, called "Nearth" has one smallish very dark moon close in, and a large moon farther off with a very high albedo. Nearth is exactly the same as ...
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1answer
77 views

Consequences of a two-mooned system losing the one closest to the planet?

I was thinking of adding rings to my planet and I wanted to give them a proper origin, so I thought about getting rid of the moon closest to the planet since I would still have one and it could make ...
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2answers
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Would the Earth with 4 moons still be habitable?

I'm currently writing about an Earth sized planet that is 33% water and has 4 moons all the same size as our moon. All moons are 243,000 miles from the planet's surface and the planet takes 392 days ...
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5answers
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How would I make a moon appear black in a night sky that has a nebula visible in it?

So, I'm developing a world for my fantasy setting, but I thought it'd be neat if this particular world had a nebula visible in its night sky. (So, it might not be a nebula like the kind we have in ...
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3answers
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What should the size of my moons be?

(Not entirely sure if this is the right place to ask this but hopefully I'm right!) I'm writing a novel and the planet this novel takes place on has two, twin moons of approximately the same size. ...
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3answers
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Capturing a moon: Process reality check

Background: I have an icy moon on a collision course with my fantasy world. Mages on this world have the ability to slow the speed of the moon gradually. I want them to use this power to lock the moon ...
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3answers
217 views

Lifetime of the Moon's moon

Imagine if the Moon had its own moon. A moon (likely an asteroid) that lies within the Moon's Hill Sphere. I have read elsewhere about the fate of such a moon. Over time due to the Moon being tidally ...
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1answer
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What happens if a small moon is held within a planet's Roche Limit?

For story reasons, I need my mages to convert a moon on a collision course with their planet into a ring around the planet. The only thing they can do is hold the moon still. They can't do so ...