Questions tagged [astronomy]

For questions related to planets, moons, stars and other celestial objects, and their motion on the sky.

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3 answers
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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?” ...
81 votes
21 answers
8k 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 ...
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40 votes
5 answers
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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 ...
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27 votes
7 answers
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Could life form in outer space?

All life we know of to date (presumably) formed on a rocky planet (more precisely: earth). Fiction has been written about life in more exotic locations. Though as far as I know, these lifeforms were ...
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51 votes
2 answers
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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 ...
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68 votes
19 answers
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How would an astronaut conclude he's on Earth, but 600 million years in the future?

Say we have a group of space travelers who have been frozen inside a sleeper ship for an enormous amount of time that left when Earth was recognizable. When they thaw out and reach their destination, ...
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33 votes
4 answers
967 views

What Factors Could Cause a World to See "Northern" Lights Much Closer to the Equator?

I'm currently designing a world where the inhabitants see the Aurora Borealis on an almost nightly basis almost all the way to the equator. The lights are so strong they rarely see the stars beyond. ...
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16 votes
3 answers
966 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 ...
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13 votes
4 answers
4k views

Detecting a neutron star entering the solar system

In its wandering through the Milky Way, the solar system is getting close to a solitary neutron star. The neutron star will "fly by" above the plane of the ecliptic and its closest distance from the ...
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42 votes
14 answers
8k views

Can I keep our universe, but without the speed limit (of light)?

It seems like nothing can move faster than light and this is quite bothersome for interstellar travel. It takes decades in the best case to get anywhere interesting in our little Milkyway (Many ...
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36 votes
5 answers
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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 ...
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23 votes
5 answers
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Is it safe to orbit HDE 226868?

I'm considering a story where an exploration is devised to explore a binary system containing a black hole; the choice is Cygnus X-1, with its companion supergiant star HDE 226868. It would likely be ...
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17 votes
4 answers
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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 ...
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15 votes
7 answers
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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 ...
14 votes
5 answers
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Can a habitable planet have mini-suns (i.e. solar satellites or glowing moons)?

Suns are stars. They are orbited by planets, and sometimes other stars. Planets are orbited by moons. Reasonably advanced civilizations may launch artificial satellites into orbits around their planet ...
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1 answer
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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 ...
19 votes
4 answers
1k views

Earth-like Moon around the Gas Giant. Eclipse length?

Worldbuilder in dire need! I'm trying to figure out the eclipse length of a habitable Earth-like moon that is rotating around a gas giant. The story that I work on is centered on the Earth-like moon, ...
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12 votes
6 answers
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How can I set a moon on fire?

So, for reasons which may or may not pop up in a later question of mine, I need to light a small Moon-like moon on fire. Well, sort of. See, I need a small object capable of emitting a lot of light - ...
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0 votes
1 answer
757 views

Stabilizing Synchronized Orbit

The planet in my story, Ser, is actually in reality a moon orbiting a larger body called planet Rea. Ser is located in the L1 Lagrangian point, which means it takes the same amount of time to orbit ...
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125 votes
21 answers
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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 ...
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31 votes
5 answers
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Creating a realistic world(s) map - Stars

This Query is part of the Worldbuilding Resources Article. This question is a sort of follow-up to Samuel's previous world map question, Creating a realistic world(s) map - planetary systems. Lots ...
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45 votes
11 answers
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How long will it take to discover they live on a moon and not on a planet?

In my alternate reality, Earth is not a planet. It is a moon and orbits a gas giant (however it has all of Earth's characteristics, it is also full of humans and life as we know it). This is the only ...
2 votes
2 answers
3k views

Reality of a Tidally Locked Planet? [closed]

I am currently working on a futuristic sci-fi story and here comes the world building part. I have been doing researches and brainstorming for days, but I feel like I may seek creative opinions from ...
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23 votes
3 answers
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How big a black hole is needed for this story?

The story begins in classic disaster film style. A small rogue black hole is approaching our Solar System. It isn’t going to get close enough to destroy everything, but it will agitate our Sun, ...
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29 votes
8 answers
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Building the Death Star with today's tech

I found an interesting Wikipedia article, quoted in an answer here. I'm looking into writing a story where someone has built a Death Star. The purpose of this craft is important to the story (and the ...
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18 votes
6 answers
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Could a society exist within a brown dwarf?

Brown dwarf stars are cool. Both literally and figuratively; the temperature profile for cool brown dwarves runs somewhere between 225K and 600K. It's possible if not probable that there exist some ...
6 votes
5 answers
833 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 ...
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14 votes
9 answers
873 views

How to blow up a star by accident?

I have this race of space-dwarves and I need to make them homeless due to technological hubris of some kind: for plot reasons. I think that if they were to attempt to build some kind of Dyson sphere ...
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11 votes
1 answer
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Where would an asteroid have to hit earth to cause an impact winter?

I found this on Wikipedia. I'm aiming for the fastest climate change possible without that much advanced notice, e.g. perhaps a regional sized asteroid scientists miss or are too distracted to catch ...
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9 votes
6 answers
2k views

Can a situation exist where there is one pole that is hot and another cold on a planet?

I am trying to design a world where one pole is very cold, and the other is very hot. I don't mean that there would be instant death in either, but it is colder than our South Pole on one end and ...
6 votes
1 answer
299 views

I can't seem to find correct starbuilding equations that work together anywhere and am generally confused. Which ones do you use?

So far I've been using Artifexian's How To Build A Star YouTube video. The problem with this video is that it's quite old and thus outdated. The things I've noticed to be particularly weird are the ...
5 votes
2 answers
496 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 ...
4 votes
2 answers
507 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 ...
8 votes
4 answers
1k views

What is the habitable zone around my star?

I have built a star that is loosely based on a real-world star. It has the following properties: Spectral class G Mass: 1.03 M$_\odot$ Radius: 1.02 r$_\odot$ Luminosity: 1.05 L$_\odot$ Surface ...
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81 votes
16 answers
12k views

Can stars that are not powered by nuclear fusion exist?

Stars generate their energy by fusing lighter elements into heavier elements. The most common reaction in Sun-like stars is the conversion of hydrogen to helium via the proton-proton chain, but ...
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66 votes
12 answers
16k views

Could a disaster kill all (human) life on Earth but leave astronauts in low orbit alive long enough to return?

There are plenty of threats out there that could terminate all life on our little planet in varying amounts of time (Solar flares, meteors and supernovas to name a few). Are there any disasters that ...
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31 votes
4 answers
3k views

What software can prototype a planetary system?

Is there any software tool for quickly prototyping a planetary system? Ideally this should: Allow for placement of planets of different sizes and masses around a star. Allow for examination of the ...
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18 votes
2 answers
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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....
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61 votes
10 answers
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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 ...
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20 votes
4 answers
879 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. ...
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29 votes
17 answers
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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 ...
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26 votes
7 answers
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On a planet without seasons, how would people track years?

On a planet without axial tilt and with a roughly circular orbit, there would be no seasons. The climate on the planet would be, as far as I can tell, exactly the same at any time of year, and the ...
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13 votes
2 answers
474 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 ...
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7 votes
1 answer
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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. ...
6 votes
1 answer
568 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 ...
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4 votes
5 answers
7k 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,...
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23 votes
11 answers
4k views

Can you replace a sun with a burning moon?

In our solar system light and heat are, of course, provided by the sun. I was wondering if a comparable effect might be had by positing a burning moon instead? So rather than a true star, you'd have a ...
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19 votes
3 answers
34k 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). ...
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13 votes
2 answers
887 views

How can a Type II civilization influence accretion rates from a debris disk to a passing star?

This is supposed to be a test of the hard-science tag. All answers to this question should be backed up by equations, empirical evidence, scientific papers, other citations, etc. Speculative or ...
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7 votes
1 answer
882 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 ...