Questions tagged [planets]

For questions about any large astronomical bodies classified as planets, and their effects on their systems.

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5
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3answers
56 views

Can my planet have a very thin atmosphere only at the poles?

While thinking about Starfish Prime's answer to the question Algae using UV light from auroras for photosynthesis, I considered the possibility of an alternate Earth which has a normal, Earth-like ...
6
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4answers
168 views

Can realistic planetary invasion have any meaningful strategy?

The sea is used as an analogy in space travel, and sometimes it works well. Ships sail on long journeys, between distant lands, across a hostile medium. But these analogies tend to break down when it ...
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How much would an earth like planet cool if covered in ash for 100 days? [on hold]

Basically the title. I want to make sure everything on the planet wouldn’t die if the planet was covered in ash for 100 days. Thanks.
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1answer
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Will my planet work? (size, gravity, atmosphere)

I was going to sort this all out beforehand, and then write the book, but when the writing flows... you make hay. I am a perfectionist/details-oriented person, but you lose me on math/hard science. ...
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1answer
92 views

How has Venus held onto its atmosphere [on hold]

Without its magnetosphere, how has Venus held onto its atmosphere, when Mars lost its atmosphere and water when its magnetic field was turned off?
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3answers
111 views

How to find the radius of a planet given its internal composition?

Consider a planet very similar to Earth, with the same radius and the same mass. In a very simplified model of its interior, 70 % of its mass is magnesium silicate and the remaining 30 % is iron. This ...
12
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3answers
193 views

Is a carbon planet with seas of methanol on its surface scientifically possible?

I am creating a carbon planet with seas of methanol on its surface, but I am not sure that this is possible. It is predicted that carbon planets are depleted of water, since the available oxygen ...
2
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1answer
82 views

How different would the internal composition of a carbon planet be from that of Earth?

My idea is a carbon planet 50 % larger than Earth and with 5 times its mass (approximately), but I set these values ​​after investigating those of several discovered exoplanets and none of them is ...
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9answers
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Why would humanity have left Earth 2 so quickly? [closed]

In the world I am building (based heavily on the Star Wars universe setting, but more historical), humanity first abandoned Earth to travel to another planet within their solar system, which they ...
2
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1answer
109 views

What would be the consequences of a planet having a core predominantly made of Krypton?

So I'm currently working on a fan project to redesign Superman's home planet of Krypton. This new Krypton is 1.6x the size of Earth and orbits the red dwarf star known to us as LHS-2520, 27.1 ...
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0answers
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Plants and Animals “Switch Places” - How Could This Have Happened?

Setting the Scene Say that you have a planet where, like on Earth, you have a taxonomic branch of its overall "Tree of Life" graph that has all the traits we associate with the "Plant" Kingdom on our ...
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1answer
151 views

Can we realisticly ever land on alien planet? [closed]

This question is heavily inspired by Netflix series Another Life We build another worlds to be explored. Mostly by humans. However, reckless behavior of space crew of ship Salvare made me realize, ...
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10answers
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How can glass marbles naturally occur in a desert?

I had a dream that on my alien planet, there was a large desert that had naturally occurring glass marbles in the sand. My dream logic was that the sand was melted into glass and natural weathering ...
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0answers
285 views
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Plausibility of helium dominated atmospheres on super-Earths

I've been using this helpful diagram a lot for worldbuilding. Now I came to think about the fact that helium is more massive than hydrogen, thus a scenario where hydrogen escapes, but helium is ...
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6answers
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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,...
9
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5answers
357 views

What sort of solar system / atmospheric conditions, if any, would allow for a very cold planet that still receives plenty of light from its sun?

The setting I'm interested in would involve a cold planet (cold enough for most bodies of water to be frozen - I'm thinking of an average global temperature of -20C or below). The simplest way would ...
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2answers
240 views

Is there a website that will run orbital simulations because I don't have a PhD in math

I'm just trying to write a RPG adventure for a sci fi company. So when I have to figure out what kind of orbits, masses, major axis, etc are needed for the system I need to design and I see: $T=2\pi$...
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5answers
341 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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2answers
162 views

What could cause a planet to be in shadow for a 6 earth month period every couple of earth years?

My previous question ruled out having a moon orbiting a gas giant. I've got an interesting ecosystem (my bad, biome was the wrong word) that evolved based upon the idea that the world is eclipsed for ...
11
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8answers
5k views

Surviving a planet collision? [duplicate]

Let's say there are two planets about to collide. Ignoring how they got there, it seems that in most scenarios basically all life gets annihilated by energy released the collision. How slow would two ...
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2answers
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How long until two planets become one?

Two Earth-like planets collide at a (relatively slow) speed of about 1,000 kph. For all questions regarding the size and composition of these planets, just think about Earth - and these two planets ...
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5answers
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Could a singular planet have more than one diverse atmosphere?

I'm making a world which is set on a planet with two smaller "bubbles" of atmosphere at the poles, and a more stereotypical atmosphere that surrounds them. Each of the three atmospheres has a ...
11
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2answers
186 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 ...
5
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3answers
129 views

how could I move an earth sized planet? [duplicate]

How could a Kardeshev II level society move an earth-sized planet at high speed, without killing everything on the planet and access to all of the resources in a solar system similar to our own? what ...
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4answers
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A planet illuminated by a black hole?

Is it possible for a planet to be heated and illuminated by a black hole due to Hawking radiation at the same intensity as by a star? What mass and size should a black hole have to produce the same ...
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9answers
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Keeping an “hot eyeball planet” wet

Consider such a tidally locked planet: Many issues with tidally locked worlds have been discussed, but I'm not clear on how the water cycle for an otherwise Earth-like tidally locked world, would be ...
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1answer
276 views

Conditions of a more ideal version of earth

What would be the specific conditions required for a planet to be a more ideal version of Earth? I want the world to have a much larger proportion of land covered by lush jungle and forest ...
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1answer
129 views

Would A Biological “Cold Haber” Process Deplete an H2/N2 World of its H2 or N2?

Based on my reading on some science papers, large, wet terrestrial planets likely exist that are swathed in a thin atmosphere of nitrogen/hydrogen ($H_2$ & $N_2$). If life evolved on such worlds, ...
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3answers
394 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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1answer
102 views

What's the climate consequences of a planet with these characteristics?

I'm designing a new planet, but I'm having some troubles figuring out the climate. The planet's rotation axis is at a 45° angle relative to its orbital plane, and each rotation takes 24h. The planet'...
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2answers
180 views

How would a very old biosphere differ from Earth's “young” one?

On my world, the equivalent of the Cambrian/Avalon explosion happened 5 byr (2 byr after formation) ago as opposed to 0.5 byr ago on Earth. The planets rough parameters are: mass between 0.4 and 0....
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3answers
179 views

Gas Giant with solid surface

I have the feeling the answer to this will come down to ''impossible'' but let's ask anyway to be sure. We know gas Giants have no solid surface and if you tried to land on one you would fall into ...
5
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1answer
311 views

What is the largest dragon that could take off without destroying the planet?

Inspired by this answer: Suppose there is an enormous dragon sleeping underground (let's not worry about the biomechanics of how such a creature could exist). One day, it wakes up, shakes the earth ...
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1answer
136 views

Effects of multiple moons on a planet

Judging by our own planet we know what the effects of a moon on a terrestrial planet are. We also know that if a planet has two moons on the same side you would get insane tides and that two moons on ...
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3answers
412 views

How close to each other can Earth-mass planets plausibly form from the protoplanetary disk?

We occasionally get questions and answers that discuss how close to each other planets can be and still meet some criteria. For example, this answer to the question ''Habitable'' planet close to a ...
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5answers
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''Habitable'' planet close to a star

Imagine if you will a star comparable with our sun and a planet like earth orbiting at roughly the same distance around this star as our earth around the sun. Would it be possible to place a planet ...
9
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2answers
411 views

What is the theoretical maximum number of habitable planets in one solar system?

In the DC comic book universe, the Vega System is a solar system around the star Vega (Alpha Lyrae), which is depicted as having dozens of habitable planets. While it seems to be an implausibly large ...
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3answers
236 views

How to get rid of the rainforest for a desert moon with only habitable poles?

I wanna build a habitable desertworld which is a gas giant moon. The desired and already semi-fixed parameters are: mass between 0.4 and 0.25 Earth-masses only 10 to 30 percent global ocean cover, ...
6
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1answer
133 views

What set of circumstances are most likely to lead to a planet with a climate resembling the Great Plains?

Part of my story will be set on a planet where a culture similar to that of the Old West has arisen - cowboys, frontier towns, homesteaders, etc. In order to make this development more plausible, I ...
4
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2answers
243 views

What would be the effects of replacing the Moon with an Earth-like planet?

Let's assume that for whatever strange -- probably magical -- reason, the Moon was suddenly and instantaneously replaced by a planet identical to Earth in terms of mass and size. Its orbital path is ...
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9answers
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What impact would a dragon the size of Asia have on the environment?

Without going into unnecessary detail, one of the races of my world believe that the land itself is a dead god, and that by resurrecting it, it will ascend to the cosmos and carry the faithful upon ...
13
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6answers
4k views

How would someone destroy a black hole that’s at the centre of a planet? [duplicate]

For starters, the black hole is temporarily contained. But once it’s containment fails it will devour the planet. Obviously, that’s a bad thing. What’s a reasonable way to prevent that? Also the ...
4
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2answers
135 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 ...
6
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1answer
133 views

In what ways would the earth's orbit/atmosphere/ocean currents have to be different in order to create summer with long nights?

As far as I know, summer and winter are governed by the amount of sunlight absorbed per unit area, where longer days would increase the temperature along with a higher sun angle. To elaborate on the ...
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4answers
272 views

Can huge planets be seen from tiny planets?

Imagine a habitable, water covered, small earth-like orb in space. Let's call it P. From its surface, you see 2 large glowing masses, different sizes, in the sky, let's call them Bs. They are not ...
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3answers
83 views

Would Such an Axial Tilt Exist on These Worlds? [closed]

In this scenario, there are two Earth-sized planets orbiting one same sun, but they are literally as different as day and night. Both have a 48-hour rotation, but: Planet A has a polar winter in ...
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5answers
1k views

In order to successfully have 3 orbital rings around a planet how do you have to orient them?

I am writing a short story about an overworked planet whose civilization has achieved space elevators and orbital rings. The planet, which is earth-sized, has three complete orbital rings in stable ...
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2answers
187 views

How to figure out layers of the atmosphere?

Earth's atmosphere, as you probably know, is divided into five layers - the troposphere, stratosphere, mesosphere, thermosphere and exosphere. https://en.wikipedia.org/wiki/Atmosphere_of_Earth#...
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1answer
149 views

How many terrestrial moons can my planet hold?

I have a Gas Giant with 13x the mass of Jupiter. How many satellites of Earth size and mass can it hold safely in its orbit? Edit: This gas giant lies smack dab in the middle of its parent star's (...
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3answers
1k views

Hiding a solar system in a nebula

I have a planetary system with a yellow dwarf similar to our own Sun and three habitable planets. I want to hide this system from sight and long range scans in a nebula, a giant cloud of dust and gas ...