All Questions
199 questions
130
votes
21
answers
25k
views
What would make scientists realize they were on a flat world?
Scenario: While poking around in an alien ruin, scientists discover a gateway which offers instant transportation to an Earth-like world.
The Observed World: The gateway leads to an area that is ...
- 6,838
82
votes
21
answers
10k
views
Is it physically possible for a planet to have seasons of different lengths?
Those of you who have read Game Of Thrones will know that in the GOT world seasons do not have a fixed duration, e.g., a winter might last three times longer than the previous one.
I find most ...
- 2,177
62
votes
10
answers
14k
views
What would it feel like on the surface of a planet while it collides with another planet?
Let's say that something horrible has happened and a Mars-sized planet is knocked out of orbit and is hurtling towards an Earth-sized planet. How much time will they have? How will this affect the ...
- 6,066
53
votes
2
answers
8k
views
What would the sky look like from the surface of a planet with rings?
What would a planet's rings look like from the surface of that planet?
Would the rings be perceived to be stationary or move across the sky, and would the alignment of the rings relative to the axis ...
- 747
41
votes
3
answers
13k
views
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?” ...
- 1,518
40
votes
5
answers
10k
views
Can a planet survive a supernova?
The Sun has nowhere near enough mass to enter the branch of stellar evolution that would lead to a supernova, fortunately for us. However, there are planets that orbit stars that are destined to go ...
- 102k
36
votes
5
answers
7k
views
Can a planet realistically have multiple suns?
Several science fiction books I have read (including, IINM, Nightfall by Asimov) have featured planets with several suns. Some worlds where this happened wrought interesting effects on the inhabitants ...
- 2,841
29
votes
17
answers
8k
views
How could a planet have one hemisphere way warmer than the other without the planet being tidally locked?
I would like a planet that's a tropical paradise on one side but covered in ice and glaciers on the opposite side, whether it be the Southern-Northern or the Western-Eastern hemisphere.
I know it ...
- 604
28
votes
6
answers
7k
views
Why didn't we detect that exoplanet before?
In my world an alien creature claims to be from an earth-like planet orbiting a 500 light-years away solar analog star. It tells us that the planet has x mass, y diameter, z orbital period, that ...
- 968
28
votes
5
answers
12k
views
What would the effect be on Earth if Mars disappeared?
What would the effect on Earth be if Mars, in the space of one second, disappeared from the Solar System? Just simply was gone, leaving no residue, and leaving the space where it had been like it had ...
- 690
28
votes
6
answers
7k
views
How deep can the ocean plausibly be?
I want to have planet with as deep an ocean as plausibly possible. How deep can I go given these restrictions?
Planet must be in habitable zone of a star
Generally, planet should support life
Size of ...
- 45.5k
26
votes
20
answers
6k
views
Making a Planet Seem Uninhabitable
How can I make it so that an otherwise colonizable planet (or moon) can (entirely naturally) seem uninhabitable from a certain point on its surface?
Background: There are a series of immovable gates ...
- 1,768
25
votes
8
answers
4k
views
Can the Little Prince's planet actually exist in our universe?
This is a drawing by my daughter which inspired one of the elements in my story/world:
The perspective is a little bit mixed here (certainly I don't have a 15 meter-high volcano in this world), but ...
- 2,393
24
votes
5
answers
4k
views
What do Martians use for months and weeks?
Assume Mars has developed an indigenous civilization of its own, perhaps as seen in Edgar Rice Burroughs' A Princess of Mars.
Much like Earth, Mars' years and days would be significant for any ...
- 85.8k
24
votes
6
answers
2k
views
Close the door on your way out - Life lit by a blue dwarf star
I'm seeking a hard science setting for a piece of xenofiction with a decidedly non-sciencey feel. That said, there is no magic or magic technology.
The idea is as follows:
A red dwarf star has a ...
- 4,198
23
votes
4
answers
2k
views
How would solar activity change if the Sun was impacted by a planet?
Suppose that a planet whose size was somewhere between the sizes of Mercury and Jupiter impacted the Sun. Would such an event change local stellar activity sufficiently enough and for long enough ...
- 5,360
20
votes
8
answers
11k
views
How could a smaller planet than Earth have a higher gravity?
I want to build a planet (or satellite) that:
is smaller than Earth,
has a thicker atmosphere than Earth but breathable,
has neither intense volcanism, nor any extreme condition of that sort that ...
- 688
20
votes
2
answers
3k
views
What would the consequences be of a high number of solar systems being within close proximity to one another?
What would the consequences be of a high number of solar systems being within close proximity to one another? I'm mainly interested in the consequences for life on multiple planets. When I say 'close ...
- 353
20
votes
4
answers
2k
views
What would the sky look like in the SHADOW of planetary rings?
Background: I'm writing a nomadic society that lives in the shadow of their planet's rings. These rings are as wide as possible to grant them the biggest shadow. The planet has an incredibly long year ...
- 201
20
votes
4
answers
1k
views
Physiological adaptation of life on a planet orbiting a red giant.
Let's say there exists an Earth-like exoplanet which orbits a normal star, with a similar process regarding the evolution of life on earth, yet the star became a red giant during said evolution.
...
- 1,018
19
votes
8
answers
3k
views
Can a planet have asymmetrical weather seasons? Like 3 months for summer, fall and spring each and 6 months of winter?
I looked around for an answer and was unable to find it here. So can the planet have asymmetrical seasons? I want my imaginary planet to have winter doubled comparing to summer. And which astronomical ...
- 357
19
votes
3
answers
37k
views
What determines the length of a day on a planet?
The length of a day on different planets in the solar system varies a lot. For instance, Mars' day is about the same length as Earth, while a day on Venus is equivalent to 243 Earth days (source). ...
- 707
19
votes
4
answers
2k
views
How would two planets with identical but perpendicular orbits affect each other?
I'm exploring this idea for a fantasy world, and I was wondering how these planets would affect each other. The system would feature orbits in all three dimensions, not relatively flat like ours is.
...
- 343
18
votes
5
answers
7k
views
By what mechanism could a planet be locked into permanent solar eclipse?
I've got an image in my head of a world where it's just normal that the star is black with a golden halo around it - in other words, where the planet is in a state of perpetual solar eclipse.
Are ...
- 3,568
18
votes
2
answers
2k
views
Starbuilding: What is lacking in the logic behind Cosmos 2 star system generation algorithm?
Preamble
The Alternity Cosmos II is a complement to a dice role-playing game that uses heuristics based on hard-science to 'build' plausible star systems for the Alternity game:
http://www....
- 487
17
votes
11
answers
2k
views
You've made it to another star! Now, how do you find its planets?
From Earth, we can detect extrasolar planets by a number of methods; primary are detecting the wobble in a star's motion caused by a large orbiting planet, and the dimming of the star's light as the ...
- 431
17
votes
6
answers
5k
views
How would a torus world (donut shaped) have to rotate in order to have a stable day / night cycle in all of its regions?
In this universe, mass and gravity work differently so stable torus planets are possible (donut shaped).
How would a torus world orbiting a single star have to rotate in order to have a stable day ...
- 1,252
17
votes
5
answers
3k
views
Where could we add a new planet to the inner solar system?
Assume there was a super advanced alien race that for some reason, wanted to add a new planet, of lets say 1 Earth mass, into the Solar System. Where in the inner Solar System (The part of the solar ...
- 2,197
16
votes
4
answers
6k
views
Can planetary bodies have a second axis of rotation?
Is it possible for a planetary body to have a secondary axis of rotation? For example let's say there's an Earth-like body that is spinning with its North Pole facing the Sun. Imagine that the North ...
- 6,322
16
votes
5
answers
4k
views
To make a gas giant flammable
(Warning: do not try this at home-system)
Preamble
Hello humans, we need advice.
Let's say we have just successfully defeated and killed a Horror From Beyond Reason who happened to be multiple times ...
- 4,697
16
votes
3
answers
1k
views
What impact is required for a visible (from Earth) ejecta plume on Earth's Moon, and would the Moon survive?
Take the Earth-Moon system as we know it. Now, something causes a large rock to be lobbed in the direction of our moon. Exactly how that happens is deliberately left unspecified; it could be ...
- 29k
15
votes
7
answers
2k
views
Could a moon have its own satellites visible from the planet it orbits?
Say you have a planet and the planet has a moon: could the moon have visible satellites as well? I don't mean a gas giant planet, I mean something habitable by humanoids or humans.
Will the moon's ...
- 425
15
votes
2
answers
590
views
Rogue Planet Illuminated by Galactic Centre
The black hole question reminded me of an idea I wanted to implement at some point in a space campaign, but didn't go forward with because I was unsure whether it's merely statistically very ...
- 2,021
15
votes
3
answers
474
views
Planet illuminated by blue-shifted relic radiation
Are there realistic circumstances that a planet would be accelerated (either artificially or naturally) to the speed at which relic radiation becomes so blue-shifted that the planet is illuminated so ...
- 5,360
14
votes
9
answers
7k
views
Is it realistic to have 7 months in a year?
I'm aware of the property of the number $2520$. It's divisible by all integer numbers from $1$ to $10$.
One of the factorizations of $2520$ is $7×360$.
It came to my mind to make a habitable planet ...
- 363
13
votes
6
answers
4k
views
Subtle ways to render a planet uninhabitable
A violent way of rendering a planet uninhabitable being the obvious: accelerate a large enough object to a sufficient velocity that everything on the planet goes the way of the dinosaurs.
Put briefly,...
- 133
13
votes
5
answers
807
views
How would life on the satellite of a Super-Jupiter be? Is it even possible for such a satellite to be habitable?
Recently I had an idea for a world setting. A large part of this world focuses around a habitable satellite the size of Earth orbiting a Super-Jupiter. The fact that it's a moon is pretty integral to ...
- 179
12
votes
6
answers
3k
views
Do seasons occur on a tidally-locked planet?
I have done some research and so much contradict one another or I simply fail to understand.
Do seasons occur on a tidally locked planet that isn't tilted on its axis?
- 675
12
votes
2
answers
2k
views
Can a planet's axial tilt naturally change a meaningful amount in only 100 years from its current cycle?
Could a planet's axial tilt change a meaningful amount (what is needed to make inhospitable biomes even more inhospitable: hotter dry hot desert, colder north) over an extremely short period (~100 ...
- 4,697
12
votes
1
answer
1k
views
Trying to survive a passing neutron star by burrowing deep in the planet's crust?
Situation: My colony is threatened by a passing neutron star. It turns out this planet is part of a binary system and once every several hundred years it passes by a neutron star, which irradiates its ...
- 813
12
votes
2
answers
895
views
Could a planet's tidal forces break an asteroid passing very close to it?
I want a certain asteroid of my system to break into pieces as it approaches a planet, having one fragment impact the planet itself, another fragment slingshot and impact the planet's moon and the ...
- 1,281
12
votes
3
answers
2k
views
What would the star chart be like if earth had a ring?
Recently, I've seen those pictures showing what Earth would be like if it had rings, and that made me wonder, what would the sky map be like? This ring would appear as a fixed object (pretty much as ...
- 1,151
12
votes
3
answers
974
views
Can a planet be on a stable orbit at a Lagrangian point of a binary star system?
Suppose we have a binary star system and a planet at the L4 or L5 point of the orbit of one of the stars around the other. The planet is thus illuminated by the two stars from the same distance and ...
- 5,360
12
votes
1
answer
446
views
If I were to put a moon-mass object in Mars orbit, how long would it take to restart the dynamo effect in Mars' core?
Mars has an inactive mantle and core and thus little magnetosphere to speak of. Assume that a lunar mass object is placed in Mars orbit at 300,000 kilometers out (one light-second). Given the tidal ...
user44399
11
votes
2
answers
7k
views
Does Earth's direction of rotation affect day length?
Let's say Earth started rotation in the opposite direction without any catastrophic events, would a day on Earth be shorter or longer or just the same considering that speed of rotation and revolution ...
11
votes
2
answers
570
views
How long would this eclipse last?
For a moon orbiting a gas giant which is in turn orbiting a star, I want to know how long the eclipse would last for an observer standing on the moon when the planet passes between the moon and the ...
- 4,153
10
votes
4
answers
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 ...
- 141
10
votes
3
answers
733
views
What would happen to a gas giant during a supernova?
Fairly straightforward question. Imagine a gas giant planet, like the size of Jupiter, in orbit around a massive star. The star goes supernova.
What happens to the planet? Is the energy of the ...
- 321
10
votes
5
answers
415
views
Eye in the Sky Effect
Is there any conceivable way that a planet with two moons--one being visibly red to the naked eye due to its mineral composition--could align in an eclipse in such a way so that the whole effect looks ...
- 211
10
votes
2
answers
1k
views
Seasons on a planet that's tidally locked with the smaller star in a dual-star system
Consider a dual-star system, with the distances between S (larger star) and J (smaller star) similar to Sun–Jupiter. A planet P rotates around J on a 90-degree ecliptic and is Earth-like otherwise.
...
- 1,961