Questions tagged [astrophysics]

For questions regarding the application of the laws of physics to orbital mechanics, stellar evolution, and other astronomical processes and celestial bodies.

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7 votes
2 answers
320 views

Estimating thrust and kg fuel for a generation ship's journey to Alpha Centauri

Premise: A generation spaceship leaves Earth around the year 2060 on a journey to colonize Alpha Centauri A (ACA). In this fiction, fusion power is achieved in 2040, improved over 20 years, and used ...
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9 votes
3 answers
489 views

What would be the structural impact of an oscillating orbit on a planet?

Notice : If you wish to know how to make an oscillating orbit with real-world physics, you can looky-look at this question which is following mine. My question focuses on the consequences of such ...
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4 votes
1 answer
175 views

Could a planet about 30% larger than earth but only 80% as dense still support a strong magnetosphere?

I've been trying to work out a few calculations for a planet I am working on and hit a bit of a roadblock. The planet in it's current state is 1.35x the size of Earth, but in order to get a density ...
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5 votes
3 answers
123 views

Monoreactant pathway for electrical power and thrust using only hydrogen?

In Space Engineers, Hydrogen is employed as a fuel for both propulsion and for electrical power (via the Hydrogen Thruster and Hydrogen Engine, respectively). This feels unrealistic to me, and I am ...
7 votes
3 answers
314 views

Seeking good physical candidates for total collapse of the universe we live in

Bringing this question over from Physics SE where it was closed: I'm looking for an 'as close to our understanding of current physics' doomsday scenario that results from something about the physics ...
5 votes
1 answer
247 views

It would be possible to enter and exit a black hole using a Warp Drive? [closed]

Well, a Warp Drive expands and contracts space, passing it through you, technically allowing faster than light travel. And so, it would be possible to actually enter a black hole and thus, exit it? I ...
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3 votes
1 answer
124 views

How Much Solar Wind Does A Star Produce?

I need someone to give me a way to figure out how fast the solar wind from a star with a known mass travels, as well as how much solar wind the star releases in a given amount of time. I hope that it ...
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1 vote
1 answer
99 views

Predict The Orbital Eccentricity Of A Planet In A Circumbinary Orbit

Okay, I have a planet smaller than Earth that has a mean orbital radius of .9 AU, and it orbits twin suns. The larger sun has a mass of 1.15 solar masses, and the smaller sun has an mass of .45 solar ...
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3 votes
3 answers
183 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,...
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2 votes
2 answers
388 views

What would a neutron star look like up close to the human eye?

I suspect it would look something like the black hole Gargantua in Interstellar, but instead of a dark center, it would be glowing, like a star? It would still produce gravitational lensing and bend ...
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-1 votes
1 answer
233 views

How much sugar and potassium nitrate I would need to make a rocket reach the moon? [closed]

I know the question itself is kinda crazy, but a rocket need a fuel and a oxidiser to work. And in this case, the oxidiser is potassium nitrate. Well, in this video, this guy makes a homemade rocket ...
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-1 votes
3 answers
293 views

Could a ion thruster work in atmosphere with enough energy?

Well, some days ago I watched a video talking about the Halo transport ship "Pelican", which uses nuclear fusion turbines (don't worry, this question isn't about Halo). And technically, ...
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6 votes
2 answers
247 views

Influence of an inner gas giant over a solar system

I'm designing a solar system with three planets in its hot zone, two in its cold zone and three in its habitable zone. All of the planets are rocky worlds of various sizes, except for the middle world ...
5 votes
4 answers
233 views

Which space bodies have helium-3 besides the moon? [closed]

There is a certain attention given to the moon in order to use its helium-3 to supply nuclear fusion on earth. But there is some problems involving energy there that concerns me. A day on the moon is ...
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-2 votes
2 answers
140 views

Would it be possible to make a black hole using the Bose-Einstein condensate?

Well, my crazy question is whether it would be possible to make a "dyson sphere", but with the sonic black hole made with Bose-Einstein condensate (and whether it would be possible to create ...
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2 votes
3 answers
97 views

Can periodic gravitational tug and pull of binary star ensure that a planet stays extremely tectonically active?

There's a binary star system with a close pair of stars ( A1 V and G2 V), in which there's a rough analogue of our Mercury that orbits both of them - a planet that's supposed to be closest to the pair ...
1 vote
0 answers
63 views

Would it be possible to mine the metallic hydrogen from jupiter with our current technology? [duplicate]

Simply put, metallic hydrogen is obtained at absurd atmospheric pressures, becoming a stable liquid with very interesting properties. As a super conductor or simply the most efficient fuel that ...
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1 vote
1 answer
97 views

Using the densest galactic superclusters motion to see a universal structure or motion

My alien species has their science and observation based on our current understandings and observations, they have an observabe universe of the same distance as ours they have noticed the structure ...
5 votes
4 answers
493 views

Can a super-Earth of Approximately 1.5 Earth-Radius and 3.0 Earth-Mass Be Habitable?

Can a super-Earth of approximately 1.5 Earth-radius and 3.0 Earth-mass be habitable? By habitable, I mean terrestrial with liquid water on its surface, a rocky ocean floor, and no thick hydrogen/...
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4 votes
3 answers
735 views

What are reasonable densities for terrestrial planets?

Earth's density is about 5.51 g/cm^3 and it's the highest density in the Solar System of a terrestrial planet. I understand that planet density is partially determined by various factors, including ...
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12 votes
2 answers
777 views

Could a planet's tidal forces break an asteroid passing very close to it?

I want a certain asteroid of my system to break into pieces as it approaches a planet, having one fragment impact the planet itself, another fragment slingshot and impact the planet's moon and the ...
20 votes
9 answers
4k views

Earth is accelerated out of the solar system - do we keep the Moon?

I've been reading about stellar engines. The Wikipedia article on them says this about the acceleration they could provide to a star: Such thrust and acceleration would be very slight, but such a ...
2 votes
1 answer
145 views

Could a habitable gas giant with an electropshere exist?

So, there are several questions on this site about gas giants. In particular, I am mostly building off of this one: Could a gas giant with layer similar to Earth atmosphere exist? This question seems ...
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3 votes
4 answers
364 views

Detecting an escaping Earth

Suppose that, some day, for reasons, the Earth is mysteriously accelerated prograde until it reaches escape velocity. It then starts a trajectory that will take it off of the solar system. It might ...
16 votes
3 answers
5k views

A 1 kilometre wide sphere of U-235 appears in an orbit around our planet. What happens?

Let's suppose that after seeing aliens get portrayed negatively in science fiction and wishing to end the discrimination, the ancient H'andh'wh'a'vians decide to destroy Earth and humanity. As they ...
3 votes
1 answer
123 views

Could a "super-Enceladus" moon exist?

Firstly, let us define the term "Super-Enceladus". In the context of this question, a "Super-Enceladus" is a moon that has permanent or near-permanent polar jets spewing out matter ...
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3 answers
162 views

What are realistic numbers for the engineering/physics for a mag-lev train which would circumnavigate the entire planet earth?

Suppose that you were writing a science-fiction novel (or movie script). In the story, a giant magnetic-levitation (mag-lev) train encircles the entire planet earth. The ring-shaped train track is ...
3 votes
4 answers
403 views

What If A Positively-Charged and a Negatively-Charged Planet Collided?

Let's say we have two planets. Both are around the same mass and radius as Earth, and are 1 year away from colliding with each other, each traveling at 20 km/s. At first. Planet 1 has a sufficient ...
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10 votes
5 answers
1k views

Making A Geosynchronous Orbit Impossible

Here's the idea: A geosynchronous orbit is an orbit that makes sure that the orbiting satellite is always above the same spot on the planet, so its orbital period is equal to a local day there. I've ...
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1 vote
2 answers
109 views

The Orbit Of Cryomoreth

Cryomoreth is the homeworld of the Cryomonians. Its year lasts for about 273.15 Earth years, and it is inhabitable for carbon-based life. Its orbit is very eccentric, which results in its seasons. ...
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1 vote
1 answer
107 views

Sigelon's Terrible Neighborhood

Sigelon is a mountainous world that's volcanically-active due to flybys with a larger neighboring planet that has a more eccentric orbit. These volcanoes release enough soot and smog to periodically ...
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6 votes
2 answers
370 views

Spinning up the Moon: does it survive the event?

The year is 2xxx. A large asteroid is spotted on a collision course with Earth. The more time it passes, the more it is clear that the impact cannot be avoided. But when most of humanity is starting ...
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3 votes
2 answers
4k views

Black hole at the center of the planet

Okay, picture a planet so massive, a black hole has formed in its center. The minimum mass of a black hole is 22 micrograms, or the Planck mass, and whatever the core is made of, it needs to be ...
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2 votes
1 answer
704 views

What if Theia Never Hit the Earth? [closed]

Let's say that for some reason, Theia never hit Earth during the formation of the solar system. However, the two heavenly bodies ended up in a stable orbit around each other. Due to this, the Earth's ...
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1 vote
3 answers
160 views

Perpetual Day Planet

I’d like to know if this is plausible: A habitable planet that’s always day. It kinda works like this: The planet orbits its largest sun, which is also orbited by three smaller suns that share the ...
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2 votes
3 answers
143 views

How could we recover from being ejected from the solar system?

I just finished watching the newest kurzgesagt video on if the earth got kicked out of the solar system here: https://m.youtube.com/watch?v=gLZJlf5rHVs And I wanted to use that scenario in a story but ...
5 votes
2 answers
135 views

Destruction of a Trojan Asteroid by an RKV

The history During the Great War between two nations, one sent an RKV (Relativistic Kill Vehicle) towards an enemy factory as a message to show their power but not kill needlessly. The base was in a ...
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3 votes
1 answer
117 views

Chameleon Particles: Space Weapons?

Dark Energy is a force said to be responsible for cosmic expansion, and one of the theorised carriers of this force is the Chameleon Particle. To describe its effects, due to its non-linear self-...
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2 votes
4 answers
199 views

What would a world look like if everything was a billion times more massive? [closed]

All atoms are still the same size/mass - it's just that the Earth, people, grass, bugs, etc - everything is more massive by a billion times. So since the Earth would be a billion times more massive, ...
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-2 votes
3 answers
195 views

What would be the biggest threat if gravity stopped? [closed]

Suppose that the law of gravitation suddenly “stops working” one day, and all gravitational forces cease to exist. What would this mean for people on Earth? Could we survive for very long? If not, ...
2 votes
3 answers
324 views

Universe without Gravity

Imagine a theoretical parallel universe that does not have and never had a gravitational force. Loose hydrogen atoms would still have formed, and in some cases might have formed H2, but would not ...
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4 votes
0 answers
53 views

Equations for developing a hypothetical Solar System [duplicate]

I am currently going down the rabbit hole of writing a story but I would like it to be set in a universe which is believable. Therefore I am trying to create a hypothetical solar system in which the ...
16 votes
6 answers
2k views

Viability of a mega star system

So my story hinges largely upon a precursor type race centered around a single star system that went extinct tens of thousands of years prior to the modern day. Obviously, the most common way to go ...
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3 votes
1 answer
229 views

When designing a map of the local universe how should currently unknown/obscured areas be treated?

I am building a map of the local universe for my story and for the time being I will base it on the real universe and our current understandings and observations although later will likely change the ...
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17 votes
6 answers
4k views

What elements are useful for humans, but rare in our galaxy?

I know for example there is an interesting gap in the amount of lithium, beryllium and boron compared to Helium and Carbon, but I don't know how useful they are. Here is a graph showing relative ...
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6 votes
1 answer
281 views

How large and bright has to be a spaceship so that you can see it with the naked eye moving at 0.99c near Pluto?

Today someone looks up at the night sky unintentionally directly towards Pluto. There is a bright light which is impossible to mistake for a star, satellite or shooting star, as it's shaped like a ...
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7 votes
2 answers
255 views

Is it possible to colonize the center of a planet with a cold core?

Let's say you have a planet(about the size of Earth) where the core of a planet has gone cold for whatever reason. So the planet is basically just a barren rock devoid of atmosphere or electromagnetic ...
4 votes
1 answer
307 views

What it looks like inside a nebula from a spaceship?

People love nebulas and all in sci-fi, specially for space battles and all so the background looks more interesting than just black. But I am wondering, if you are inside a nebula while in a warship, ...
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7 votes
1 answer
222 views

A planet that is entirely liquid

Is it possible that a body of significant size - at least several hundred kilometers in diameter - is entirely liquid, having no solid core? It can be either made of one homologous liquid or of ...
4 votes
1 answer
249 views

What to do with planet nine if it is a Black Hole? [closed]

Recently it's been theorized that "planet nine" may be a black hole. If this was the case what could we do with it? What unresolved problems in physics could be solved by having such a thing ...