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Questions tagged [astronomy]

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

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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 ...
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1answer
187 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 ...
24
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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
244 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
131 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 ...
59
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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
330 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 ...
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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
298 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
135 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
93 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
105 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
301 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
81 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 ...
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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
187 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 ...
4
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4answers
281 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
80 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 ...
2
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1answer
296 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
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1answer
230 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
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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
57 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
120 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 ...
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6answers
244 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 ...
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3answers
166 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
471 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
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1answer
113 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 ...
1
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1answer
125 views

Big moon, small planet - can an earth sized moon orbit a moon sized planet?

I know that objects with lower mass tends to orbit objects with higher mass, is it possible to have a Moon sized planet who's mass is so heavy that an Earth sized planet orbit it as it's Moon in a ...
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3answers
3k views

How can I locate myself in a random point of space?

Some Context I'm creating a universe where humanity has reached the stars. They've colonized a few star systems and, obviously, FTL drives are a common thing. They basically jump you to another ...
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4answers
114 views

How to determine the shape of the world given that there are no astronomical cycles?

Inspired by this question, how might one determine the shape of the world given a cosmology with no cycles? The moon, sun, stars, and planets are all fixed. The Earth does not rotate. You can't ...
6
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2answers
104 views

How to distinguish the different phases of the day when the sun rises and sets multiple times?

Obviously there would be a lot of small (not to mention a couple large) changes humans would need to get used to on a planet that rotates much faster than Earth. The biggest one I’m concerned about ...
5
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1answer
100 views

Is it possible an ice line from pole to pole in a tidally locked Earth-like moon?

I am aware that there are a lot of answers explaining the fundamentals of a tidally locked "Earth-like" moon around a giant gas planet. For example this one: Habitable moon of a gas giant: working out ...
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8answers
778 views

Which part of the universe would make celestial navigation most difficult for a planet?

Premise I envisage a world of would-be navigators with roughly Bronze Age technology, sailing on ships to explore their planet. In contrast to our history of navigation where we "cracked the code" ...
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3answers
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How can I modern time traveler determine solstice and equinox?

A XX century researcher time traveled back into the prehistory. He is not in danger of death or anything, but he has only energy to attempt one jump. He must jump back during the sunrise either in a ...
10
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3answers
282 views

How can the Hertzsprung–Russell diagram be used in star building?

As you can probably guess from the title, I have some questions about the Hertzsprung–Russell diagram, especially how to use it to make plausible stars. Some questions: Can stars exist in the black ...
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7answers
7k views

How would skeptics know that a single-engine plane could not destroy a falling meteor?

So I'm writing a story and decided to use Hida Furukawa as the location. It has a high school with a field of 650 ft that theoretically could be used for a small aircraft to be use to take off. In the ...
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3answers
99 views

Weather among the average tropical coastal regions? (I can't be more specific than this since i lack a map, I apologize) [closed]

I have a super-earth world. The surface of the world is shallower due to extra gravity, so shorter mountain ranges and less ocean depths. The world orbits a binary star system at a distance of the ...
4
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4answers
161 views

Changing Earth's axis suddenly or gradually?

First post, if it isn't completely obvious. I've discovered this site by trying to "google" that question. Here's what I'm investigating: Long ago, pre-deluvian civilizations built ancient megalithic ...
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3answers
224 views

What software could I use to simulate my world's sky?

My protagonist is an astronomer in a fantasy world. Ideally, what I want is software where I can specify some properties of this planet, e.g. orbital and rotation period, nearby stars, number of ...
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5answers
4k views

Would everything be miniature on a miniature Earth?

If there was a planet half the earth’s diameter, for which every other aspect of the earth was changed proportionally to keep the Earth’s perfect ratio intact (including having the perfect orbital ...
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2answers
202 views

Tiny galaxies with exoplanets

Segue 2 is a galaxy with only about 1000 stars and is 111 light years in radius. It has a light output only 900 times that of our sun. (This is a real galaxy in our universe) However, I want my ...
10
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4answers
2k views

Could a world exist with a distinct line of changing temperatures between the hemispheres?

I'm trying to create a world where there's an equator-like divide running along the axis(?) of the planet and the two hemispheres are perpetually different in terms of temperature. Basically, I want ...
6
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1answer
383 views

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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1answer
56 views

Stationary trinary system

I am creating a world in which a civilization has achieved advanced spaceflight and has begone colonizing other planets in their solar system that is similar to ours, but with more planets. However, ...
3
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1answer
138 views

How long can a moon remain non-spherical, and what might it look like when full?

I'm trying to "build" a world in which the moon is always visible at night, and only at night, to the majority of areas on that world. I've been told that an L2 Legrange point could be a viable ...
15
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3answers
487 views

Could the Sun be born again?

About 5 billion years from now, the Sun will begin to swell into a red giant. This will cause some problems, because life on a planet orbiting a red giant is hard. Even if Earth isn't engulfed by the ...
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1answer
184 views

Feasibility and consequences: the cosmic dance of twins habitable moons

I am aware of being a newbie in the field I am asking my question... please be kind and explain what I did wrong if I make a mistake. The idea from where the problem bloom I love worldbuilding. ...