Questions tagged [astronomy]

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

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7 votes
7 answers
212 views

Locating rogue planet in deep space based on astronomical observations from its surface?

Assume that you have a Rogue Planet hurtling through deep space. Somehow, an alien civilization from, say, 1,000 ly away acquires astronomical data from this planet. This data is in the form of high ...
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8 votes
2 answers
671 views

What's the largest igneous province an impact event could create on Earth?

With the potential for an impact event to trigger volcanic activity on the opposite side of the planet, what is the largest plateau of flood basalt physically capable of forming on Earth, post-impact?
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2 votes
2 answers
100 views

Is it possible for a large planetary body to embed itself onto the Earth?

With the proper composition and mass, is it possible for a planetary body to collide with Earth and embed itself onto the mantle? To clarify, while immense destruction would undoubtedly occur to the ...
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7 votes
2 answers
329 views

If humans evolved on Mars instead of Earth, how quickly would we have detected life on Earth?

Suppose that both Earth and Mars was booming with life in a similar way. Except that, on Earth, there was no hominid family, and no humans evolved. Instead, humans evolved on Mars. Assuming we had ...
2 votes
1 answer
56 views

Is it possible for an impact event to render the Earth's surface unrecognizable while still forming a large complex crater?

Is it physically possible for a complex crater to form and remain stable after an impact event large enough to deform the Earth's crust globally, insofar that the surface of the planet becomes ...
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6 votes
1 answer
207 views

What does and doesn't work with this planetary system around a red dwarf?

So I have the following scenario for a story, and I want to know if it runs into any ridiculous no-nos from a scientific point of view: There is an earth-like world orbiting a red dwarf (similar to ...
4 votes
1 answer
150 views

Could intelligent life arise on a planet that isn't 'tethered' to a star, just drifting near to one? [duplicate]

Earth's movement in space is obviously linked to the Sun, as are many other planets. But what I'm asking, is could intelligent life develop on a world that is merely 'passing by' and basking in a ...
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6 votes
3 answers
380 views

How Likely is a Planet Made Almost Entirely of Metals?

For this question, the word 'metals' does not refer to elements heavier than hydrogen and helium. It instead refers to metals as defined by the periodic table of elements. After researching the ...
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12 votes
3 answers
5k views

Can planetary bodies have a second axis of rotation?

Is it possible for a planetary body to have a secondary axis of rotation? For example let's say there's an Earth-like body that is spinning with its North Pole facing the Sun. Imagine that the North ...
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0 votes
1 answer
757 views

Stabilizing Synchronized Orbit

The planet in my story, Ser, is actually in reality a moon orbiting a larger body called planet Rea. Ser is located in the L1 Lagrangian point, which means it takes the same amount of time to orbit ...
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6 votes
1 answer
239 views

Could a planet be habitable due to illumination from the galactic core?

I recently saw this answers where it was suggested that the galactic core could illuminate a planet suffiently to make sure it is always summer on one side of the planet. This got me curious and after ...
29 votes
17 answers
7k views

How could a planet have one hemisphere way warmer than the other without the planet being tidally locked?

I would like a planet that's a tropical paradise on one side but covered in ice and glaciers on the opposite side, whether it be the Southern-Northern or the Western-Eastern hemisphere. I know it ...
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6 votes
5 answers
177 views

Planetary neighbors

Let's say there is another planet in our solar system that harbours sentient life and this sentient life can build castles, buildings, and other such structures. When would we notice that? We can ...
9 votes
4 answers
2k views

Moons that can't see each other

Could 2 moons that orbit same terrestrial planet never see each other if they orbit the planet at same time? Moons have different mass and gravity.
5 votes
2 answers
732 views

What would happen if the Earth passed through an interstellar dust cloud?

I understand an interstellar dust cloud as "an accumulation of gas, plasma, and dust in our and other galaxies. Put differently, an interstellar cloud is a denser-than-average region of the ...
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13 votes
6 answers
4k views

Subtle ways to render a planet uninhabitable

A violent way of rendering a planet uninhabitable being the obvious: accelerate a large enough object to a sufficient velocity that everything on the planet goes the way of the dinosaurs. Put briefly,...
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11 votes
2 answers
378 views

The North Star in the ancient world sky

Question: Would a modern-day teen, trained in using the north star for directions when camping/hiking, notice a difference in how the "north star" (Polaris) works when transported suddenly to 1350 BCE?...
8 votes
5 answers
442 views

Can early astronomers determine the gravity of their planet's "moon" without ever going there?

As I was thinking about space flight for my world, I thought about how they would need to know a planet's gravitational force before they could land, and found that humans figured out the moon's ...
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13 votes
2 answers
474 views

Rogue Planet Illuminated by Galactic Centre

The black hole question reminded me of an idea I wanted to implement at some point in a space campaign, but didn't go forward with because I was unsure whether it's merely statistically very ...
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7 votes
2 answers
443 views

Life around Cepheid Variable stars

Are there any unique challenges life would face evolving on a planet orbiting a Cepheid Variable star? I'm aware this is a broad question, so to narrow it down, consider this a question about Great ...
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5 votes
3 answers
786 views

Aliens blew up Pluto so we would stop debating whether or not to call it a planet, what happens to Earth? [closed]

It seems the Fraxians, an alien race from Alpha Centuri, have been secretly watching our television ever since we started broadcasting it (well technically I suppose 4.367 years after we started ...
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6 votes
1 answer
462 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 votes
2 answers
507 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 ...
5 votes
1 answer
113 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, ...
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3 votes
1 answer
88 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 ...
3 votes
4 answers
166 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 ...
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4 votes
2 answers
377 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 ...
8 votes
5 answers
803 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 (...
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20 votes
2 answers
3k 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 ...
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11 votes
2 answers
382 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 ...
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6 votes
2 answers
319 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 ...
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31 votes
5 answers
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, ...
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6 votes
2 answers
572 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 ...
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8 votes
1 answer
167 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 votes
4 answers
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 ...
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11 votes
6 answers
1k 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 votes
2 answers
299 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; ...
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9 votes
1 answer
315 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 ...
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3 votes
2 answers
159 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 ...
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-3 votes
1 answer
314 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 ...
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13 votes
18 answers
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 ...
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4 votes
2 answers
577 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
1 answer
337 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 votes
13 answers
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 ...
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7 votes
10 answers
328 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 votes
4 answers
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 ...
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5 votes
4 answers
151 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 ...
64 votes
24 answers
13k 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 ...
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6 votes
1 answer
445 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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23 votes
6 answers
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 ...
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