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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How long would Earth be habitable after being knocked out of orbit? [duplicate]

Let’s say a rogue planet or something came close enough to Earth to knock it out of its orbit. Whatever event causes this, can this happen without disrupting human life in the short term and how long ...
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What are hard sci-fi mechanisms for a society of sentient planets? [closed]

IN BRIEF: I'm wondering if anyone has any hard mechanisms/explanations in mind for a planet-sized single consciousness that's able to move itself freely in space while developing its own distinct ...
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4 votes
5 answers
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How would a spaceship not affected by gravity navigate between planets?

Presume there exists a metal called X-matter that has all the properties of steel, except it is repulsed by normal-matter instead of attracted. (For instance, a block of it would accelerate 9.81 m/s/s ...
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7 votes
5 answers
419 views

Galactic 'geographic' features, how could they impact galactic colonization efforts?

I have been wondering how galactic features could impact interstellar civilizations in the process of colonizing a galaxy (either andromeda or the milky way). According to this video these features, ...
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4 votes
2 answers
136 views

What are the effects of Increasing the gravity on Mars?

I'm interested in the Physics around increasing the gravity of Mars to make it habitable. I was unsure how to work out what gravity would be needed to retain an atmosphere thick enough to hold liquid ...
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3 votes
1 answer
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How to place multiple small moons and one large moon in stable orbit around an earthlike planet?

Earth has one very large, spherical moon believed to have been formed by a giant impact. Mars has two small, sorta potato-ical moons believed to have been captured. Suppose an otherwise earthlike ...
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3 votes
1 answer
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Can moon people generate electricity using a gravity dynamo that is turned by the gravity of their host planet?

On Earth, we generate electricity from the Moon's orbit using tidal turbines. Would it be possible for denizens of the Moon to generate electricity using the Earth's gravity, using a windmill-sized ...
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8 votes
6 answers
4k views

If Earth had a smaller radius, but was rotating at the same speed, would its day be shorter?

I want to make a hypothetical planet that is 26% the mass of earth, with 64% the radius. Because I want a relatively short day to keep temperatures more stable, but I don't want a super fast rotation ...
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3 votes
1 answer
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How would a high escape velocity effect conditions on a low gravity Birch planet?

A birch planet is a theoretical far future Giga-structure where a shell world is built around a supermassive blackhole. I have been playing around with different astrophysical calculators to find out ...
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3 votes
1 answer
121 views

What kind of atmospheric composition would make the sky look green and still be breathable?

In my story scientists discovered a planet that look green from the telescope and they used a advanced starship to go there and the y found out that the planet is habitable with a breathable ...
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4 votes
2 answers
256 views

What would happen if a neutron star approached the solar system?

Given its enormous eletromagnetic field and gravity( and probably gravitational waves would be very powerful) what would happen if a neutron star approached Earth? What if approached just by few light ...
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4 votes
2 answers
76 views

Day/night cycle and tracking celestial positions in S-type binary star system

I know this has been asked before but I'm going to pose the question again under slightly different circumstances and with a more specific goal. I'm trying to work out the details of how the day/night ...
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2 votes
2 answers
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Could a molecular cloud turn the Sun into a killer star?

Let's say an unknown cloud enters the Solar System and begins manipulating the Sun, destabilizing the magnetic fields. Could it end up causing the Sun to emit gamma ray bursts to render the system ...
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7 votes
1 answer
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Figuring out the precise location of Earth a certain amount of time ago

Movement is relative, but I've read that an ex-NASA scientist has quantified the speed of Earth hurtling through space to be 1.3 million mph, using the Cosmic Microwave Background as a frame of ...
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6 votes
3 answers
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how plausible is this exomoon?

(this is doublet of my previous question, so I did a little improvement on it) -my exomoon is around size of venus, but a little bit smaller. is very windy, so windy in fact filter feeders thrives in ...
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4 votes
4 answers
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What are the odds of a binary solar eclipse?

I'm currently creating my own binary star system which includes a circumbinary planet that has two moons. For simplicity's sake, the stars, planet, and moons are comparable in size to our own Sun, ...
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11 votes
4 answers
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How could a galaxy be damaged by a civilization's industrial expansionism in ways that mirror our own current climate crisis?

There are several stellar environmental results from sentient industrial over-expansionism that I can imagine ie. star lifting that results in entire systems becoming frozen husks and debris from ...
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6 votes
4 answers
219 views

Could there be biomes inside of asteroids?

I don't mean "biome" in the strict scientific definition, but rather, in the broader geological sense that it is used by game designers to refer to unique environments. On earth, when people ...
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2 votes
3 answers
200 views

Could the electrical charge of a black hole neutralize it's gravitational pull?

It's well-known that gravity is the weakest of the 4 fundamental forces. With this knowledge, would it be possible to cancel out the gravitational forces of a black hole with it's charge? Say a black ...
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1 answer
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Relative masses of Binary Systems

I'm writing a sci-fi novel and I have an some astrophysics questions. First, is it possible for a binary system to be made up of a large gaseous planet and a dwarf star? I know it's possible to have ...
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3 votes
1 answer
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Where should I place my Earth-like planet within my binary system?

I am working on a RPG setting which requires my planet having a nearby flare star. I understand from reading through other, similar questions and from doing some research, that flare stars are ...
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2 votes
2 answers
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Days with a torus shaped Sun

What would day and night look like on Earth (or any habitable planet), if the sun was torus shaped, with the same circumference? And moreover, how much the Earth will be affected, if the sun was ...
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1 vote
1 answer
131 views

Two celestial bodies tidal locked - not with the sun

I tried to do my homework and actually thanks to this question and answer, I found myself to this site. But I just found more questions :) Basically the setting would be close to what Earth - Moon is, ...
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3 votes
3 answers
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Is delta v relevant for interstellar travel for generation ship?

Imagine I have a generation ship that is heading to a nearby star system say 10 light years away, the average lifespan for the crew is 150 years on Earth and is expected to increase by about 5 years ...
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3 votes
1 answer
101 views

How Far In Advance Could People See A 100-1500 Meter Earth Bound Impactor Before It Hit

How much advanced notice would we likely have in advance of an Earth bound impactor with a place of origin outside Earth's orbit (e.g. a meteor, asteroid, comet, space debris that doesn't rotate ...
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2 votes
1 answer
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What Size and Likelihood Of An ET Impact Would Destroy A Small County Sized Region But Not Our Species?

Motivation The question is inspired by the astronomy journal preprint released publicly today, entitled: From impact refugees to deterritorialized states: foresighting extreme legal-policy cases in ...
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8 votes
2 answers
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Time scale and mechanism to “realistically” remove Sol from the Milky Way

What is the fastest rate a star could be flung out of our galaxy and by what mechanism(s)? (i.e. from a gravity kick by a hypothetical passing hypervelocity black hole) Secondary question: how far ...
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-4 votes
1 answer
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How could a human with infinite strength crash a planet into earth

A bad guy was kicked off earth and lands on another planet or dwarf planet. He has magical powers that let him have as much physical power as he needs to accomplish his goals. He is also extremely ...
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4 votes
1 answer
266 views

How big can a whirligig/planetcake get while still maintaining human-survivable gravity at its equator?

A whirligig/planetcake/whatever punny name you want for it is a super-sized planet (we're talking about Jupiter masses here, not Earth masses) that spins so quickly that it's shaped like a pancake (...
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5 votes
4 answers
345 views

What would the local effects/affects be of a ring spinning near luminal velocity?

To better solicit more inline with what I'm trying to imagine, I'm editing my question, the original question is left below and removing the hard science tag, as that just seemed to cause issues, ...
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6 votes
4 answers
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Moon hit strong enough to put it in a slow spin?

I’m building a world nearly equal to earth; i need a catastrophic event that make the moon start spinning breaking the tidal lock, a really slow spin, like 500 years for a full spin. i thought about a ...
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7 votes
2 answers
243 views

Aliens pressure cook the Solar System, do we notice?

550 million years ago, aliens erected a spherical barrier 1/6th of a light-year (~10,000 AU) in radius around the solar system, centered on the solar barycenter. Things outside the barrier can enter, ...
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5 votes
3 answers
338 views

Enlightening Dark Matter?

As an ironic twist, I wanted a story in which dark matter is actually caused by light. Somehow, the physics of light cause it to create the appearance of the existence of dark matter. But I'm not a ...
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1 vote
1 answer
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Would a gigantic meteor impact in the Strait of Gibraltar create a peak-ring crater, or at least a complex one?

Background: A peak-ring crater is a sub-type of complex crater (an impact crater in which the impact wave rebounded from the rim of the crater and pushed up a mountain in the middle) where, instead ...
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0 votes
1 answer
123 views

Would a meteor blowing up the Strait of Gibraltar 2 million years ago kill all of humanity's ancestor species?

Let's say that, 2 million years prior to the present day, a meteor impacts roughly in the middle of the Strait of Gibraltar. It is large enough and strikes at sufficient velocity to create an impact ...
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8 votes
2 answers
291 views

Effects of magic on stellar evolution

I believe it'd be foolish to assume that magic wouldn't affect astronomical phenomena like stellar evolution, But since I'm not smart enough to create the equations for a new fundamental force, I have ...
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5 votes
1 answer
164 views

What would happen if a planet gradually lost mass?

The idea I have is to have a planet that, at its core, has a being that gradually eats away at the planet's substance and converts it into massive amounts of energy (think matter-antimatter ...
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7 votes
2 answers
285 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
470 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
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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
116 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 ...
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7 votes
3 answers
298 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 ...
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5 votes
1 answer
228 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
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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
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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
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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
351 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
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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
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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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  • 151
6 votes
2 answers
232 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 ...
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