All Questions
199 questions
8
votes
1
answer
2k
views
The (Alternative) Reason for the Seasons: Highly Eccentric Orbit
On Earth, we experience seasons because of our planet's axial tilt.
It is a common misconception that the seasons are instead caused by our planet's distance from the sun changing as it orbits. The ...
- 4,797
5
votes
7
answers
2k
views
What would allow a livable planet to have an always-night area, an always-day area and a day&night cycling area?
I'm wondering what natural phenomenon would allow a planet to have a part of its surface always under daylight, a part of its surface never seeing said light, and a third part where day and night ...
- 105
5
votes
2
answers
1k
views
Tidally locked planet with day & night cycle
I'm wondering if it is possible for a planet to have one pole always facing its star, the other always facing away (by rotating as if a tidal-locked planet), but style have a day and night cycle on ...
- 105
5
votes
3
answers
875
views
Proxima Centauri and tidally locked planets
Proxima Centauri may have a rocky, earth like planet close to its dim sun. Tidally locked, the sun facing side may have a temperature up to 30 degrees Celsius and a dark side of -30 C. This would make ...
- 3,785
6
votes
5
answers
2k
views
Mistake an uninhabitable planet for an inhabitable one
Given advanced enough telescopic technology, would it be possible to detect that a planet in the order of 50 light years away is inhabitable? (i.e. without having to actually go there)
I'm just ...
- 9,527
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
7
votes
5
answers
2k
views
Could this stellar system exist within 10-20 light years from Earth, undetected?
After reevaluating my sense of perspective on sublight interstellar travel, I'm thinking of moving my planet closer to Earth to cut down on travel time and fuel costs. However, the planet my colonists ...
- 11.3k
1
vote
2
answers
309
views
Consequences of having a gas giant as a neighbour instead of Mars
Assuming we had a gas giant instead of Mars in our planetary system. Everything else stays the same. Which long-term and short-term consequences for life on Earth would I have to take into account?
- 579
1
vote
4
answers
173
views
Under the following conditions, would any technological civilisation build a chemical rocket, and if so, how?
I have a captured planet/moon orbiting HD 37124 c, known as HD 37124 c m XVIII, and I was wondering: since the moon has 1.7 Earth masses, 1.1 Earth radii, a density of 7.038 g/cm^3 and a gravitational ...
- 1,373
5
votes
2
answers
712
views
Heavy metal planets in a globular cluster
Globular clusters are old, dense groups of stars that tend to have relatively few metals (in this case meaning any elements heavier than helium). Clusters near the galactic core tend to have more ...
- 1,768
4
votes
1
answer
497
views
Habitable moon of a gas giant: working out the size of the tide
I'm creating a fictional planet that orbits a gas giant (a lot like Jupiter). I'm working out all the issues listed here
and here.
But what I'm really having trouble with is the size of the tide. In ...
- 61
5
votes
1
answer
323
views
Could my moons-planet system be stable?
In my fictional world I have selected all parameters to maximize the Hills Sphere of my planet. The planet has three times Earth's mass and it is located in 2 AU from its star that's 1.4 times more ...
- 53
3
votes
1
answer
426
views
Fusing Mars and Ganymede
Would it be possible to move Ganymede into Mars' orbit causing them to fuse together like the two proto moons of earth?
The new planet "Marmede" would have a mass equal to 13.2 % of Earth.
How ...
- 39
3
votes
2
answers
196
views
Planet trajectories in a made-up night sky
The people from my made-up world are strong believers in astrology. Their culture and religion revolves around the relative positions of the planets of their solar system.
Are there any resources (...
- 5,808
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
4
votes
1
answer
525
views
Binary planet eclipses
I know that on a binary planet you would have planetary eclipses (basically like a solar or lunar eclipse but with planets instead of moons).
If there also is a moon, things would be much more ...
- 4,165
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
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
9
votes
1
answer
361
views
What natural processes can cause a sidereal day to be significantly longer than a sidereal year?
Most of the planets that we know of have a sidereal day (rotational period) that is shorter or on the same order of magnitude as their sidereal year (orbital period), the latter being the case in ...
- 29k
5
votes
3
answers
177
views
Astronomy on a maximally spinning Earth
Let there be an earth-sized planet with a rotational period of just over 3 hours and 38 minutes described by David Hammen here . On this oblate spheroid, with nights lasting for an hour and 49ish ...
- 3,729
5
votes
1
answer
402
views
Building a perfectly spherical world
EDIT: Question has been altered significantly in terms of design (originally having been a 'what-if'). This should (hopefully) accommodate more grounded and specific answers.
Science often prefers to ...
- 163
5
votes
3
answers
657
views
Could a solar eclipse occur just after a lunar eclipse?
Would it theoretically be possible for a solar eclipse to occur within a few days or even a few hours after a total lunar eclipse?
The star, moon, and planet from which the event is being observed do ...
10
votes
3
answers
860
views
'star factory' that a planet orbits?
I am working on a novel of a fantasy world on another planet. I am not too concerned with scientific accuracy, as again, it's fantasy, but I am not interested in supernatural things for my world. That ...
- 103
8
votes
4
answers
897
views
How similar to earth could a planet which experiences a permanent day be?
I want to play with the idea of a sapient species evolving on a world where at least part of the world experiences a permanent day. The obvious way to doing this would be where part of the world ...
- 33.9k
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
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
7
votes
2
answers
1k
views
Would it be impossible for me to have a nebula in my planet's night sky?
I'd like to be able to see from my Earth-like planet, a very bright nebula that can even be seen during the daytime.
I question, however, whether that is possible, because in order for it to be ...
- 17.4k
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
5
votes
2
answers
560
views
What is the best planetary orbit around a black hole in order to support life?
Note: I am aware of a previous question
Physiological effects of living on a world close to a black hole
As I understand it, that question refers specifically to a planet that is in a non-ideal ...
- 49.5k
3
votes
3
answers
818
views
What happens when a tidally-locked planet breaks out of the synchronous rotation?
Say you've got a hypothetical human-colonized planet planet roughly the size and composition of Earth orbiting around an M-class star a third the size of the sun at 0.2 AUs. Due to the proximity, this ...
- 33
3
votes
3
answers
694
views
What is required to make watery, blue-white colored jovian planet at habitable zone of a star
Background
In my story, HD 28185 star system harbors life. One of them is a jovian HD 28185 d (Subralis), located around 1AU of this sun-like star. In-universe, Subralis is approximately 132,000 ...
- 2,020
7
votes
1
answer
1k
views
Apparent magnitude of my moon as seen from the planet's surface
Setting: we have a fantasy world which is a planet with much of the same conditions that can be seen on Earth, but with the difference that it is orbited by a moon with a mean diameter of 3 500 km. ...
- 734
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
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
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
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
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
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
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
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
7
votes
3
answers
1k
views
Is this shattered planet scenario possible?
Suppose there's a planet that has similar characteristics of Earth and can provide life, suddenly shatters in many pieces and scattered over the system. A small but very dense object is attached into ...
- 73
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
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
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
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
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
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
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