Questions tagged [astronomy]

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

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6
votes
1answer
138 views

Is it possible to have a planet with earth-like mass but double the atmospheric pressure?

I'm no scientist and my poor brain box is on its last legs; I was wondering if any of you smart beans out there would be able to help me figure this out? Here are the specs of my system; Kereiol is a ...
4
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2answers
117 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 ...
3
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1answer
100 views

How Far Can The Stars Ve and Vili Orbit The Main One, Odin?

In this solar system, there are three K-type main sequence stars, or "orange dwarves", named Odin, Vili and Ve. At the center of this solar system, Odin is 80% the mass of our sun. The middle star, ...
2
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1answer
72 views

If Janus and Epimetheus had moons

Imagine a planet with two moons that have an orbital pattern similar to that of Janus and Epimetheus of Saturn... Is there a way for one of these moons to keep a stable pair of Trojan sub moons? I'm ...
2
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4answers
113 views

Intelligent life wiped out in a binary system with a neutron star?

For the purposes of my story, I have created the following setting. An Earth-like planet orbits a binary star system made up of a Sun-like star and a neutron star. For the majority of time (hundreds ...
4
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2answers
176 views

If a moon shattered into pieces, what would happen?

Say I have a planet with 10-20 moons of varying sizes orbiting it. If one of these moons were to explode/shatter into tiny pieces (I know this is probably impossible, but if we pretended it were ...
5
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3answers
304 views

For people on earth, is it possible to harvest energy by decelerating the planet rotation?

I was working on a side project to design an alien fleet that is wandering in the universe, and harvesting energy from planets for their needs. While I can think of ways to make that happen (...
19
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2answers
2k 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 ...
10
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2answers
182 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 ...
7
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2answers
217 views

At What Point Does a World's Twin Planet Disappear, from the Viewer's Perspective?

This is Yeola~Camay. A double planet orbiting Sharro, an ordinaryish star somewhere in the universe of Far Far Away. As you can plainly see, Yeola is the planet on the left & Camay is the planet ...
31
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5answers
11k views

If Sweden was to magically float away, at what altitude would it be visible from the southern hemisphere?

If a chunk of land mass the size and position of Sweden took off and floated away in a straight line, exiting the atmosphere and orbiting earth, at what distance would it be visible from, let's say, ...
5
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2answers
486 views

Could a brown dwarf in our outer solar system remain undetected today?

We've all heard the on-again, off-again theories of another massive object in the vast reaches of the outer solar system. Some potential evidence to support the possibility are its affects on smaller ...
7
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1answer
91 views

Visibility of a Red Dwarf Companion Star

An interstellar traveller stands upon the surface of an alien planet beneath the light of an unfamiliar sun. The planet upon which he stands orbits one star of a binary system in which one is a G-...
14
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4answers
5k views

Would mining huge amounts of resources on the Moon change its orbit?

Imagine that humanity builds mining facilities on the moon. We know that the moon has Helium-3 which could be used as fuel for fusion reactors. Also, there are a lot of other resources which could be ...
9
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6answers
271 views

What light would my cloudy planet receive from a red dwarf star?

What light spectrum would hit the surface of a planet orbiting a red dwarf star? The planet is a humid greenhouse with a cloudy atmosphere and a strong ozone layer. Over 80% of the surface is water. ...
6
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2answers
193 views

Black hole collides with Sun: How rapidly is energy released?

Basic idea: Primordial black hole (2.5% of Sun's mass) directly approaches Sun at fairly rapid pace (300 km/s). Consequently, six days after passing Earth's orbit, it will collide with the Sun; ...
9
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1answer
195 views

To make a blue moon, what element does it need?

We know that Mars has a reddish color, because its ground consists of iron-based compounds. The moon is grey-whiteish because it consists mostly of silicon-based compounds. What element should the ...
3
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2answers
107 views

Is there a plausible causal mechanism to explain why the Sun would be heating up faster/ sooner than we thought?

I am writing a novel about what it will be like on earth 500 or so years before the death of our Sun. The Sun is heating up gradually and one day that will negatively affect life on Earth. I know that ...
-3
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1answer
285 views

In a world with 12 moons but NO sun, how to define a day? [closed]

I made the map of my fantasy world before thinking about the physics, as you can see bellow the art! I'm interested to understand how to decide which moon is in the sky at a given moment, if it's ...
13
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18answers
4k views

How can a moon have an ever-changing face?

Imagine an inhabitated planet like ours with a moon of the same projected size in the sky. The moon has visible structures of colors or darker and lighter areas. Every evening when the moon gets ...
4
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2answers
211 views

How much heat would a 1km asteroid release into earth's atmosphere?

I am writing a theory for a game that is in an apocalypse. An asteroid is heading for earth and will crash into the earth regardless in this theory. It is 1km in size but due to the YORP effect it has ...
1
vote
1answer
208 views

Is it possible to divert a 1km Asteroid from Earth?

I am writing a scenario for a game that I am a fan of. It involves an asteroid heading for impact with the Earth in 2027. This asteroid's initial diameter is about 1km, but it is slowly disintegrating ...
26
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13answers
6k views

How can a planet have a deadly eclipse-like “spotlight”?

A solar eclipse occurs when the moon passes between the Earth and the sun. The result is a giant shadow that sweeps across the Earth's surface. This world has the opposite phenomenon. Instead of a ...
7
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10answers
276 views

Plausible reasons for multiple hot seasons in one solar year

Setup: A planet generally with an earthlike climate, although slightly wetter and warmer as a general rule, with a little more oxygen in the atmosphere, but habitable by unmodified humans. Still has ...
12
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4answers
2k views

How close could another solar system be without adversely affecting our own?

I would like to know how close two planetary systems could be without having an adverse effect on each other. My goal is to drastically improve the chances of having habitable planets near enough that ...
5
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4answers
142 views

Small eclipse on earth

Could one make a smaller eclipse kept stationary on the surface of the earth in order that one may be able to see the stars 24/7 from one site? How could this be achieved? Geostationary satellite ...
61
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24answers
12k views

How could a planet have a sky without stars at night?

Is it possible for a planet in our part of the galaxy to have a night without stars? I'm looking for some kind of natural phenomena that would hide the stars, but allow the sun to rise and fall as ...
6
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1answer
353 views

Does my plot point centered around eclipses make sense?

My main antagonist is an infant Great One that's been imprisoned below the Moon's surface and I want its influence and physical form to have a weakness to direct sunlight which, I think, gives me a ...
22
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6answers
2k views

Scientific explanation for a exceptionally bright night sky

On an alternative Earth live the people of Tcelonia. One of their founding myths goes that, in the dawn of times, when they were under the menace of being attacked by an enemy population, for an ...
34
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11answers
5k views

What's an astronomical event which happened about 10,000 years ago, which humans could have noticed?

Bob is older than he looks. Specifically, even though Bob looks like he's in his twenties or thirties (it's hard to tell), he was actually born in Europe about ten thousand years ago, long before the ...
6
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2answers
340 views

How far out can a pre-telescope human society (naked eye observations only) detect planets?

There are many questions on WBSE that cover most aspects of building a planetary system. (some examples below): Creating a realistic world(s) map - planetary systems How many planets should I have ...
7
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2answers
140 views

Let's float an island on an astrophysical jet

An astrophysical jet is a stream of particles emitted by matter falling into an supermassive star/black hole, travelling at up to 80% the speed of light. A troll with a portal gun (which places ...
5
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2answers
107 views

Naturally maintaining an atmosphere being stripped by a brown dwarf‘s magnetosphere

In this scenario we have a brown dwarf with a powerful magnetic dynamo from metallic hydrogen. The magnetic field is modeled after Jupiter’s but just three orders of magnitude more powerful. ...
5
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1answer
168 views

Explaining a Low-Mass Brown Dwarf

Considering the well-established relationships between stellar mass, surface temp, and luminosity, how unusual would it be to find a star (or brown dwarf) that possesses about half the mass of an ...
9
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2answers
366 views

A supermassive black hole is coming our way. When's the latest that we would notice?

I'm trying to build a story around a supermassive black hole, which is ejected from a merger of two galaxies, that is hurtling our own way. What is the smallest realistic distance at which the black ...
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1answer
135 views

Estimates for undetectable planets in extra-solar systems [closed]

Based on answers and comments on some previous questions (especially this one), and as very clearly illustrated by the scatter-plot here, there are some very definite limitations on our ability to ...
8
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6answers
1k views

Can a 15km, rapidly-spining asteroid go undiscovered until the asteroid belt is being actively explored?

What I want to know is if an asteroid about 15 KM in diameter and roughly double that in length, spinning at a significant speed, could go undiscovered until a crew of an asteroid mining ship happened ...
3
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3answers
217 views

Could a comet cool down global tempatures? [duplicate]

In warlords I wanted Terrans to have a fad of big (synthetic) fur jackets, but I didn't want too have everyone running around in winter clothing for no good reason so the solution my mind instantly ...
5
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4answers
311 views

What requires more destructive energy? Destroying a planet or splitting a planet in half

I just wanna ask which option requires more destructive energy? Option 1 : destroying a planet like earth to rubble (tiny pieces of rocks) Or Option 2: splitting a planet like earth in halves (2 ...
4
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2answers
93 views

What are some plausible formation explanations of a non-hot “Fluffy” Gas Giant planet?

So, in my research and preparation for the question I asked immediately before this one, I was introduced to the concept of "fluffy" gas giants, gas giants with significantly lower density than would ...
3
votes
1answer
368 views

Feasible star + planet + moon combo? Did I miss anything that makes this system wildly unstable or otherwise impossible?

Here's what I've come up with: The star: A main sequence star, roughly a sol analogue Younger than Sol (say 3-3.5 billion years old) roughly the same starting mass as Sol, but has had less time to ...
6
votes
1answer
357 views

Could [life on] Earth Survive a Gamma Ray Burst?

[EDIT: this question is about life on Earth surviving, not the physical destruction of the planet] Could the Earth survive a gamma ray burst if that burst occurred in our galaxy and the Earth is in ...
9
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8answers
2k views

What is our planetary defense capability against an Earth life destroying object?

This is World Building through a preventative measure. The Earth has been destroyed a few times in the past and it will happen again in the future, it is just a matter of time. For the first time in ...
3
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2answers
64 views

Opaque Solar Shield in Geosynchronous Orbit: Plausibility + Challenges of Maintaining Orbit

Suppose humans of the late 21st century or beyond began constructing a solar shield as a solution to climate change. Suppose for some reason (open to suggestions) they choose to build the shield in ...
4
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2answers
135 views

Editable map of local stars

I'm looking for a map of stars within a few hundred LY of the Sun. I'd like to be able to add text tags to stars, so I can name them within my SF universe. Then I'd like to be able to rotate the image ...
5
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6answers
255 views

What sort of setup of a binary star system would allow only one sun to be “up” at a time?

I have a sci-fi/fantasy world with two suns. Only one sun can be present in the sky at a time. A full day-night cycle would be: Night time Sun 1 rises Sun 1 sets Sun 2 rises Sun 2 sets Night time Is ...
7
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3answers
187 views

Are there any plausible 'alternative' methods of planetary formation?

The selected answer on this question provides an extremely good, and detailed, description of what is generally accepted to be the main (only?) way a terrestrial planet can form, i.e. through ...
4
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2answers
482 views

What would happen if a little less than half of the moon crashed into the Atlantic ocean? [duplicate]

Let's say an asteroid hit the moon and broke it in half. One half remains where the moon usually is relative to Earth, and the other half is flung at Earth near the equator, in the Atlantic ocean. ...
43
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11answers
9k views

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 ...
10
votes
1answer
128 views

Increased Luminosity in Stars

I'm trying to construct a solar system, and I'm toying with the idea that the planet capable of sustaining life was initially outside of the habitable zone, but the star's advanced age has caused the ...