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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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Effects of a close approach with a non-pulsar neutron star?

My hard-ish SF story requires an event that would effectively render the entire solar system completely uninhabitable for some time (i.e. retreating underground for a few millennia won't help), but ...
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1answer
121 views

Determining Planet rotation period that would allow for global Wind Cell

I'm trying to figure out how quickly a planet could rotate while also having a single air flow cell, such as Hadley cells, that would circle from hot pole to cold pole, etc. as in the case of Tidally ...
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5answers
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160 Year Solar Orbital Period & 1.9 Year Moon Orbital Period - Is it possible?

A defining factor of my world is the hardships inhabitants have to face when surviving long seasons. Due to the extreme length of a year, time is largely measured by moon cycles. I need to make sure ...
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18answers
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Why would space fleets be aligned?

Recently I noticed how space fleets are all constructed so the ships are all aligned. With 'aligned' I mean the way how all ships seem to have a 'right way up' and that all the ships have the same ...
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2answers
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What's the biggest, most spectacular asteroid collision the moon could save us from?

An asteroid collision big enough and fast enough to see a massive ejection of rock and moon-chunks, from the surface of the earth AND not wipe out the population of the planet. What size and speed of ...
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2answers
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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 ...
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7answers
381 views

“Landing” a small asteroid on Earth

I've been poking around similar posts, but none seem to contain the information I'm looking for. I'll try to keep it brief. In the year 20XX, some powerful organizations are trying to "land" an ...
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4answers
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Can planets collide and not melt together?

Ok so I've been going around on the internet trying to figure out whether or not when 2 earth like planets of similar densities and makeup collide is it possible for them to bounce off of each other ...
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1answer
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Are Planets with mainly one climate Biome Plausible? [duplicate]

So i'll start by saying it feels like a somewhat stupid question in the sense that the answer is no, but im wondering if (for back story of races in a story) its realistically possible for a planet to ...
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1answer
197 views

How to make a bigger planet be as similar to Earth as possible

My fantasy world is slightly larger than earth so that discovery of the continents becomes harder (about 20% surface should do it). But at the same time I want to preserve most aspects to make it like ...
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1answer
56 views

apply forces such that satellite reaches a given point in space

The problem is the following: let's say we have a miniaturized satellite*, X; we know its position, velocity, acceleration, the forces applied at any given moment; we also know its mass, its ...
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4answers
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Could the moon crash into the earth if we colonised it and increased its mass?

Suppose we begin to colonize the moon. Assuming the building materials and biological material are all imported (not taken on-site), would it be possible for the moon to become massive enough to fall ...
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2answers
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Equation to get the size of a crater created by a meteor strike?

Im trying to find the equation to the the size of the resulting crater created by meteor strike when I have the mass, volume, diameter, density, velocity and kinetic energy of the meteor Can ...
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2answers
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Effects of the shadow of a city in the sky?

If there was a city using antigrav to maintain a position over Kolkata, and it had approximately the area of New York City (roughly 300 square miles, or 780 square kilometers), what altitude would it ...
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2answers
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What is the minimum size for the Sun?

How small could our Sun be and still "burn" with nuclear fusion and emit the same spectrum of light and other radiation as the real Sun does? Edit: The goal is to have a small sun inside a huge ...
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2answers
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How much mass does an object in low earth orbit need to create visible gravitational effects on the surface?

The question stems from watching a scene from ID2 and seeing the massive alien mothership landing/crashing on the North Atlantic. What mass would a starship, or any other artificial object ...
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3answers
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Weather and climate of tidally locked, inhabited moon with oceans

This follows another question that brought me some curiousity about the general state of an earth-like moon tidally locked to a gas giant planet. There's been questions about a world tidally locked ...
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3answers
745 views

Would a water-bearing, Earth-sized moon orbiting a gas giant have tides?

I ran across this article today about how moons might have moons. In Daniel Keys Moran's universe, an Earth-sized planet named November orbits a gas giant named Prometheus. November is inhabited, ...
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4answers
386 views

Could humans go from earth to an exoplanet 5 times the size of jupiter

If humans were to travel from earth to another planet that was an exoplanet 5 times the mass of Jupiter ("Rocky earth like planet"), would they be able to survive? Background: The planet I was ...
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4answers
778 views

Pink Atmosphere [duplicate]

I recently came across a planet that I found pretty interesting but I can't seem to find much information about its characteristics. Its atmosphere is pink in appearance. After looking at the picture ...
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12answers
3k views

Aliens to play a mischievous space-time practical joke on Earth

Premise Suppose an earth-like world in the near-future. Then aliens come and decide to play a mischievous trick on this world on an epic scale. The goal is to disrupt Earth's time by 18 minutes. ...
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3answers
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Can Mercury's orbit be explained without relativity?

The orbit of mercury is different than rest of the planets. The reason for this seemed unaccounted for in Newtonian physics, and was later explained by Einstein's theory of relativity. Here is a ...
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2answers
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Threats within 100 light years

So I'm making this game where the player has to launch probes into interstellar space within a 100 * 100 light years map to detect threats that could wipe out humanity in a few decades. Everything is ...
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1answer
165 views

How do I create the largest possible space habitat for humans? [closed]

So I'm making a post-FTL world in which humans are the first, and so far only, species to explore the stars. It's thousands (if not millions) of years in the future, and we've become post scarcity. ...
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6answers
420 views

How could you tell if someone was messing around with your gravity?

I'm working on a story involving first contact with an alien species that bases their space travel on directly manipulating gravity fields. My question is not about how that would work, but rather how ...
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1answer
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Building a planet with a primordial black hole core

I have been trying to figure out a way of explaining how an advanced society some time in the past built an artificial planet with a black hole at its core and the effects that would have on the ...
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1answer
280 views

Radiation Levels and Effects on Planet with 27 Suns

Other posts from this thread will be posted here: How to make an Earth with 27 suns work (Closed as a duplicate of the follow up, Attempt Two) How To Make an Earth with 27 Suns Work, Attempt Two: ...
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3answers
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Could a thermonuclear detonation be ignited in a star by addition of sufficient energy instantaneously in a small region?

While it does not occur in nature, I have wondered if a sufficient amount of energy deposited in a sufficiently small space in a sufficiently small amount of time could ignite a thermonuclear ...
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1answer
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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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4answers
1k views

How To Make an Earth with 27 Suns Work, Attempt Two: Orbital Stability

This is the continuation 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 Radiation ...