All Questions
59 questions
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
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
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
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
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
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
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
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
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
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
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
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
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
6
votes
5
answers
949
views
Making a slow orbit around a large gas giant
First of all, this website is a dream come true. I'm a total sucker for this stuff.
Secondly, I love astronomy and worldbuilding, and lately, I've been thinking of a hypothetical situation, and was ...
- 61
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
4
votes
2
answers
617
views
Looking for a review of my tidally locked red dwarf planet system specs!
Hello! I've put together my first planetary system, but as I'm not a scientist (and bad at maths) I'm reaching the limits of my brainbox and would really appreciate some fact checking! I have ...
- 421
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
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
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
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
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
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
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
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
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
7
votes
1
answer
1k
views
How Would It Feel To Walk On A Rocheworld?
A while back I saw this video talking about the habitability of double planets and Rocheworlds. I haven't seen any questions about the latter case here, so I decided to take a swing at it.
For some ...
- 2,952
7
votes
1
answer
1k
views
Is this circumbinary planet set up in a stable manner?
This is the ideal set up for my solar system:
EDIT
It's been pointed out that this is not a stable set up, so I want to clarify that everything in this set up can be changed at will to fit my planet. ...
- 901
6
votes
1
answer
667
views
I've determined how many planets my solar system could plausibly have. How do I figure out what kind of planets they are?
The 12 planets in my solar system orbit the G-type star of Nemo. It's about nine-tenths of the size of the sun, and has a stellar luminosity of 0.67 L☉, a diameter of 1.28 million kilometres, a ...
- 14.9k
5
votes
8
answers
891
views
How can a small planetoid hold an atmosphere under artificial means?
Edit: Before I give up on this I wonder how could an advanced civilization create conditions on a small planetoid (Ceres sized?) to keep an Earth level breathable atmosphere? It seems like its ...
- 4,948
4
votes
5
answers
8k
views
How to make an Earth with 27 suns work [duplicate]
Viability of Many Suns
This is the first of a thread of related posts on a hypothetical alternate universe/Light Plane.
Other posts from this thread are here:
How To Make an Earth with 27 Suns Work,...
- 3,246
3
votes
3
answers
260
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,...
- 33
1
vote
2
answers
507
views
Is this model possible? Fast axial precession + tidal locking
I'm working on a story set in a planet of permanent dusk/dawn, and with a dark side that never sees the light of sun. I know that a planet tidally locked to its star would (roughly) look like this, ...
- 1,151
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
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
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
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
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
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
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
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
8
votes
4
answers
2k
views
Is there a plausible way to have a Gas Giant with two or more earth to mars sized moons orbiting it in the Habitable zone?
A hypothetical scenario I'm batting around in my head is a Habitable Gas Giant system consisting of a roughly Saturn sized body orbiting a sun like star at a comfy goldilocks zone distance. Orbiting ...
- 766
8
votes
6
answers
593
views
Could an Irregular Orbit Cause Significantly Longer Seasons?
I have a fantasy world I'm making, with a planet and sun similar to our world, except the length of the seasons are significantly longer. Each of the seasons last two years, and the full seasonal ...
7
votes
1
answer
5k
views
How to calculate the solar day from sidereal day and sidereal orbital period?
I know the orbital period of my planet and the rotational period of my planet. Now how do I calculate the solar day? It would only be a small difference to be sure, but do remember that if we didn't ...
- 71
7
votes
5
answers
515
views
How could an iron planet be geologically active?
So I have an iron planet, and its name is Randall.
Since Randall is an iron planet, he is basically the core of a planet with no crust/mantle, and very few silicates. Now, I, the creator outside of ...
- 2,197
6
votes
6
answers
509
views
Is it possible for a planet about 1/5th larger than earth in radius to remain earthlike?
The planet in question has a radius of 7947km, volume 1.9408 times as large as earth, & a weight about 1.55377 times that of earth.
I want the planet to be earth like, or at least earth like ...
- 5,163
6
votes
3
answers
600
views
How would it feel to sail a Rocheworld ocean?
A couple days ago, I posted this question about what it would feel like to walk on a Rocheworld.
For some background, a Rocheworld is a double planet system where the two planets are so close ...
- 2,952
5
votes
2
answers
302
views
Can my planet maintain a magnetic field after being tidally locked?
I'm designing an Earth-like planet that has a mass of 1.9 that of Earths' and a gravity of 1.44 g. It is orbiting around a k7v orange dwarf star at a distance of 0.47 AU and with an orbital period of ...
- 1,811
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
983
views
Aliens blew up Pluto so we would stop debating whether or not to call it a planet, what happens to Earth? [closed]
It seems the Fraxians, an alien race from Alpha Centuri, have been secretly watching our television ever since we started broadcasting it (well technically I suppose 4.367 years after we started ...
- 33.9k