Questions tagged [astronomy]

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

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F type and K type Star Binary

I'm designing a worldbuilding project and the first major hurdle I'm encountering is the star(s) I want to have. The primary star is an F9V - F8V star with a mass of 1.13 - 1.15 Solar Masses, a radius ...
Dono's user avatar
  • 181
3 votes
2 answers
1k views

What is the minimum size of a natural satellite needed to shield radio telescope signals from its planet?

Edit: Edited the title, following Mazura's suggestion, for a better wording of the question. NASA and other space agencies have considered installing radio telescopes on the far side of the Moon. The ...
Christmas Snow's user avatar
7 votes
7 answers
2k views

Do (supermassive) black holes rotate? [closed]

Premise Trying to come up with a way to have a galactic unified time/date system, I turned my eye on the sidereal rotation period of, for example, the Sun, or, on the desired larger scale, Sagittarius ...
MarsMagnus's user avatar
3 votes
1 answer
78 views

Calculating the Amount of Time for the Precession of the Equinoxes [duplicate]

OK, so in the process of building a world for my D&D campaign, I have gotten very into the science of world building. Where I have gotten hung up is I want to have a realistic length of time for ...
ZeldaChloëRose's user avatar
2 votes
3 answers
315 views

Can you calculate Atmospheric mass/density based on planetary mass?

Premise Tangential follow up to my earlier question about Chthonian planets. Question What I am wondering is if, given a planets mass and radius, you could calculate its likely atmospheric mass and ...
MarsMagnus's user avatar
6 votes
3 answers
779 views

Could a Chthonian planet develop life?

Premise: Can a Chthonian planet develop life? The questions is much less if it could develop living organisms, but more if it can develop the building blocks necessary for organic life: An atmosphere, ...
MarsMagnus's user avatar
7 votes
9 answers
3k views

What reasons might day and night be very similar on a planet

I have a planet where I would like the distinction between night and day to be minimal. It is usually bright and it is usually hot. The best I can come up with is a tidally locked planet, where ...
trubliphone's user avatar
0 votes
0 answers
78 views

How far away can a tidally locked planet be from a star?

I have a planet in my worldbuilding project that, fifth planet from its small (compared to the Sun) star, which is meant to be tidally locked. Could a planet as far away that be tidally locked?
Dorothy Vivian's user avatar
3 votes
2 answers
109 views

How do I figure out where a moon is in the sky at a given time and place?

I use this planetarium tool to see the position of the Moon to check I have it in the right place for a given place and time, for my non-Earth plant. I'm considering having another moon. How would I ...
Syntal's user avatar
  • 53
2 votes
1 answer
105 views

At what approximate distance and what size should binary planets be for a day to be no more than 30-32 hours long?

For the story I'm trying to find a more or less plausible description of the planet. Initially I was considering planet size like Mars or mid-size between Earth and Mars. Аnd this planet is in tidal ...
Tanya's user avatar
  • 23
4 votes
2 answers
279 views

What seasons would look like on a supercontinent on the planet-facing side of a tidally-locked moon

I have read through previous questions here about seasons on a tidally-locked moon (I'm hoping this is far enough away from those to not be a duplicate question) and I think I understand the theory of ...
SaintDiabolus's user avatar
1 vote
1 answer
112 views

How deep can the oceans on my planet realistically be? [duplicate]

I want to know how deep the oceans of my super-Earth can plausibly be. Is there any way to calculate the depth of my oceans? Here are the characteristics of my planet to help with the calculations: ...
user107608's user avatar
0 votes
1 answer
99 views

Positioning the second sun in a binary star system so that a tidally locked moon of a gas giant is not illuminated by it, but the gas giant is

Working off this question and its suggestion of binary star systems to increase the length of 'day' on a planet without increasing the length of 'night' I have a gas giant (1.2 Mass/Jupiter, 1 Radius/...
SaintDiabolus's user avatar
0 votes
0 answers
33 views

Size of parent planet in the sky from a tidally locked moon [duplicate]

TLDR: Can anyone explain to me (like I am five and very bad at math, the latter of which I actually am) how to determine the size of the parent gas giant in the sky of my moon? EDIT: I am asking for ...
SaintDiabolus's user avatar
0 votes
2 answers
348 views

Implications of Venus and Mars having the same mass as Earth

Could anyone advise if there have been any simulations on the long term stability of our solar system if Venus and Mars both had the same mass as Earth ? If not, is this something that can be answered ...
Adrian's user avatar
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1 vote
0 answers
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How do I make a Lunar Calendar for a planet with three moons and two suns on either side? [closed]

The planet is about three to five times the size of Earth and it shares a solar system with 13 other planets and they have an ∞ shaped orbit around two suns on opposite sides of the solar system. The ...
Los3r_ghost_tale_factory's user avatar
1 vote
3 answers
120 views

How long would a day/week/month be in a world where a year was the equivalent to four months here? [closed]

I am new here and I wish for someone to help me with this question that haunts me with writer's block. I am writing a story that is set in a world where each year lasts the same time as four months ...
Los3r_ghost_tale_factory's user avatar
1 vote
1 answer
264 views

Can a terrestial planet have a core of metallic hydrogen?

Let's say somehow, a yellow dwarf like our sun was sent hurtling through space, and smacked into a red giant with enough force to cause the two to go supernova. With the release of large amounts of ...
TheGoldenBoy2188 The Coolest G's user avatar
2 votes
1 answer
129 views

What's the maximum mass for an Iron Planet to have a magnetosphere like Mercury's?

I'm designing an iron planet which migrated into its habitable zone. Basic research told me iron planets cool off too quickly to have a magnetic field, so initially I was looking for ways native life ...
Thoth's user avatar
  • 317
2 votes
1 answer
107 views

Effect of molecular clouds on space travel and civilization

To What Extent are Molecular Clouds Geographic Barriers in Space? In a sci-fi universe I've been working on for quite a while, I have different civilizations that are initially unaware of each other's ...
EldritchEntity's user avatar
3 votes
1 answer
78 views

How visible would stars be from a planet orbiting an M-class star?

I have a planet orbiting at 0.2067 AU around a M-class red dwarf of mass and luminosity 0.4037 Msol and 0.0286 Lsol, respectively. The planet has an atmosphere of 93% CO2 and 3 atm. What I wonder is, ...
Ylahris's user avatar
  • 487
1 vote
4 answers
448 views

Solar Flux required to boil oceans?

What amount of stellar flux that a planet receives is required to boil away all oceans on said planet? We're thinking of Q🜨 (Earth = 1.00 Q🜨). For comparison: Venus ~ 1.93 Q🜨, Mercury ~ 6.57 Q🜨, ...
Sussus Amogus's user avatar
2 votes
2 answers
160 views

How axial precession affects the night sky

I am working on the model which can visualise how the night sky change over time (from observer's point of view). I was thinking how axial precession affect positions of stars and planets on the night ...
Bedlasky's user avatar
  • 131
0 votes
1 answer
217 views

What Stars Do I Need to Make a Railgun?

Alright so I have come up with this idea for the primary weapon of a particular class of mages in my fantasy world: the Railgun. These mages are called starborn because, when they are born, they are ...
skout's user avatar
  • 2,068
2 votes
2 answers
160 views

If Earth were located at 1.1 AU from the Sun, would this affect the two zenithal passage days in the Tropics?

I am designing calendrics for an Earth-like planet located 1.1 AU from a Sun-like star. On Earth, on April 30th and August 13th, the Sun appears to pass directly overhead between the Tropics of Cancer ...
JM Yaden's user avatar
  • 305
4 votes
2 answers
590 views

Would an increase in star density affect the "Goldilocks Zone"?

Let's say that there's a solar system that matches the description of Sol exactly, save for the fact that it's 20,000 light years closer/farther to the galactic center. Would the zone of one ...
Jarren_Takar's user avatar
2 votes
2 answers
345 views

Could a captured planet end up in the habitable zone of a new star system?

Is it possible for a planet to be ejected from one star system and end up in the habitable zone of another? Or do captured planets always end up in wide, eccentric orbits? I guess in the vast expanse ...
Elhammo's user avatar
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8 votes
1 answer
868 views

How might planet size affect volcanic activity?

I'm working on a project involving the evolution of life on different hypothetical habitable planets. In imagining different atmospheres on planets of different masses, I'm wondering how a planet's ...
Elhammo's user avatar
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4 votes
0 answers
131 views

How magnitude affects angular diameter/resolution

Let's say you look at two relatively dim stars in the night sky. They are close to each other, but they are far away enough that you can distinguish one from the other. But what if one of them is much ...
Bedlasky's user avatar
  • 131
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 ...
Snack Exchange's user avatar
2 votes
2 answers
234 views

Is it possible for polar nights at one pole to be 8 & 1/2 months long without significantly messing up the climate?

Is it possible for polar nights at one pole to be 8 & 1/2 months long without significantly messing up the climate? The length of polar nights at the south pole from what i know is a week longer ...
OT-64 SKOT's user avatar
  • 4,182
6 votes
6 answers
445 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 ...
OT-64 SKOT's user avatar
  • 4,182
1 vote
2 answers
149 views

Reverse engineering the Hill Sphere?

I'm wondering if anyone has run into the issue of "I know the general idea of how big my moon is but not the parent planet" and how to sort of reverse engineer finding out the mass/radius of ...
Deep Stone Costco's user avatar
4 votes
3 answers
238 views

Could a slow rotating planet combined with high density atmosphere create high winds?

I am trying to design an alien ecosystem around a K type star. My idea was to have purple plants and high wind atmosphere so originally I wanted to make it tidally locked. However after watching some ...
Radu Dan Coroian's user avatar
4 votes
2 answers
133 views

Trinary star system - Tidal locked planet [closed]

I'm trying to build a world where an earth-like planet is tidal locked to a sun in a three star system, where the other two would orbit each other in the center (being the central mass of the system). ...
Vitones's user avatar
  • 43
3 votes
5 answers
242 views

What are some pseudo-scientific ways to explain the qualities of a yellow dwarf hyperstar?

Basically, in my stories, there’s a habitable, Earth-like planet called Ozarvis 32. It is the 32nd planet from the star of the Ozarvis Stellar System, which has 68 planets, 12 of which are in the ...
Godzilla Louise's user avatar
2 votes
1 answer
144 views

How do I make an Earth-like habitable planet tidally locked to a red supergiant (class L or M)?

Assuming tidally locked planets have the potential to be inhabitable: Is there any way for a planet of Earth-like size to become tidally locked to a red supergiant of class L or M?
Mensch79's user avatar
2 votes
1 answer
83 views

What could cause a star system's protoplanetary disk to fragment more easily?

Essentially I'm looking to fill a star system with as many planetary bodies as I can, and I figure the larger the objects get, the more planets get crushed together or flung out of the system. There's ...
Rexotec's user avatar
  • 381
0 votes
0 answers
45 views

How many giant planets could form in a hierarchical triple star system?

The system in question has a very close binary pair of 2 G-type stars, a G9V and a G7V, orbiting at about 0.2 AU, with a K2V star in a far orbit about 300 AU out around the both of them. There is a ...
Rexotec's user avatar
  • 381
2 votes
1 answer
65 views

What stellar temperature, orbital distance, and eccentricity is needed to create an Earthlike orbital planet with a last glacial maximum climate?

I am creating an Earthlike planet with a year length of 515 Earth days and 9 Earth hours. I am aware that Kepler's third law of planetary motion states that warmer stars are needed for longer orbital ...
Galactic's user avatar
  • 4,474
3 votes
2 answers
126 views

How fast would this astronomical macromorph be?

I’m taking inspiration from Robert A. Freitas Jr.’s theory about alien metabolisms based on gravity rather than electromagnetism. He imagines astronomically sized beings that derive energy by ...
Fredrik Hansing's user avatar
1 vote
1 answer
166 views

A brown dwarf world

I’m thinking about making a detailed world on Luhman 16 B (not around the star, right on it). This brown dwarf's mass is 28.6 times that of Jupiter and has a radius 104% that of Jupiter. It has a ...
Fredrik Hansing's user avatar
10 votes
9 answers
4k views

What star would cause a planet to have white plants?

Okay, I'm trying to make a planet that has at least part of its surface, or at least part of its underground, habitable for humans (breathable atmosphere at a suitable pressure, a suitable level of ...
Tyson Dennis's user avatar
4 votes
4 answers
411 views

Why does daytime on my planet resemble twilight/dusk?

The setting is science-fantasy, so there are some unnatural features that dictate the properties of the setting, but I'd rather not rely on it. So basically this planet is very similar to our own, but ...
Demiurge777's user avatar
2 votes
2 answers
132 views

Is a p-type binary system with two suns and two moons possible? [closed]

I want to have a fantasy setting with two suns and two moons. Ideally, the stars would be 5 million km apart, orbit each other every 10 days, and pass in front of each other every 5 days, creating an ...
marimosa's user avatar
2 votes
2 answers
167 views

Trojan Planet Skies

A few questions here have broached the possibility and survivability of life on a Trojan planet, a planet that exists at the Lagrange point of a larger celestial body. In this particular question, the ...
Mahahus's user avatar
  • 95
19 votes
8 answers
7k views

How long would it take us to detect that the earth had been enclosed in a shell 1 light year in radius?

Suppose we put a shell around the solar system that displays a 2D image of the rest of the universe on its inner surface. What year would we have had telescopes powerful enough to determine that this ...
Adam Kabbeke's user avatar
  • 1,983
2 votes
3 answers
168 views

Does my binary planet make sense?

I have a binary planet as the setting for a sci-fi story, and I would like to know if this system makes sense or if there are any major flaws. I am also open to suggestions for improvements. Here is a ...
grat's user avatar
  • 29
3 votes
3 answers
1k views

How would an observer from a moon the mass of Earth orbiting a planet 81.3 time more massive be able to tell that they were orbiting with 1660's tech

For questions sake assume that this moon is a perfect recreation of Earth on January 1st 1660 and that the planet looks identical to our moon on the same day. The Planet would have a mass of 81.3 ...
KaiserVonMegalo's user avatar
7 votes
5 answers
486 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 ...
KaffeeByte's user avatar
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