Extreme Planetary Features vs realism

[Naima]

Thanks that side is indeed interestig .

Still I would propose some new ideas possibilities .


Nebula proximity

How would work a world with a Huge big nebula visible in their sky ? Woudl have any effect like radiation , killing lifeforms or instead would have mostly no effect and allow the civilizations to rise?

Nested moons
Coudl a moon have a secondary moon orbiting it ? What consequences coudl be on the Earth?

Moon of a Larger Giant gas
Coudl a Earth develop under the influence of a giant Gas ? What coudl prevent Radiation to kill anything on the surface? what are the conditions to
support an Earthlike planed with a Big Saturn or Jupiter in the Night Sky?

Twin suns
How would work Earthlike planets with a double sun in the sky shining on civilizations? Woudl those rise ?

Twin Earths ...
Could perhaps two earths orbit one near the other and form a double minisystem with both supporting life?

Ring in the Sky
What could cause to have a Earthlike planet a Ring of detrites all around the planet just Like Saturn?


Btw on the

Large igneous province
I meant a huge land of Lava , not only some Volcanic activity in a region ... Its a pretty like a sea of Lava or a lava lake on
the open surface .

Axial Tilting periodical movements

Could be possible small Axial tilting movements that bring the axis of the Earth much more down during a period and
upper in others so changing drastically the Climate based on very small periods ( at least geologically ) like for example
every 10 years or every 50 years or even less? Would that affect much the flora and fauna of the regions ? Perhaps
adapted climatic plants? Or massive migrations?

A mount Olympus ( from Mars ) Volcano on Earth
would air be breatheable still on its top ? how woudl be even gravity?

Large Chasms
I think we all have seen a lot of Large Chasms in the soil on most fantasy maps , but are those actually possible in RL
and what woudl be their origin ? how massive they could be ?

[Azélor]

Nebula proximity
yes, some nebula are visible from earth, so life is possible

Nested moons
Yes but it seems it's really rare. You need to meet different conditions

the smaller moon need to be in the inside the Hill sphere of the larger moon : Hill sphere - Wikipedia, the free encyclopedia
the smaller the second moon is, and the larger the larger moon is, the easier it is to make it fit in the sphere. The Hill sphere will be larger if it's far from the planet.

so the consequences are limited because the moon can't be too big or too close to Earth. To test more specific scenario you could try Universe sandbox, there is a free trial: Universe Sandbox


Moon of a Larger Giant gas
I don't know enough to answer


Twin suns
Yes if the second star is far enough. The closer it is, the hotter it becomes. Until the planet become a desert.
You can have 2 stars orbiting close to each other near the center of the system. The impact on the temperature could be small if you put the planet farther from them.
You can have the planet orbit 1 star and having a second star (smaller) orbiting around the main star but very far away. Or have the closest star orbit the other star is also possible.

Twin Earths ...
I don't know, they could become tidal locked to each other. Some parts of each planet would never have direct sunlight.

Ring in the Sky
having a moon that orbit too close to the planet. If the moon is small enough and if it's closing the distance slowly (and not crashing) it will disintegrate and create a ring. If the moon is too big, it could fall on the planet instead and killing pretty much everything.

You could also imagine a scenario in the future where the rings are made either of space junk or orbital infrastructures.




Large igneous province
Lava does not erupt in large quantity so it usually cools down pretty fast. That said, there was a time where earth was mostly made of lava. So it's possible but the planet could not host lifeforms without advanced technology.

Axial Tilting periodical movements
dunno

A mount Olympus ( from Mars ) Volcano on Earth
according to my knowledge some species could survive (in the lower stratosphere which is lower than the Olympus)but not humans. there is not enough oxygen.

Large Chasms
There is plenty of Chasms on Earth! The grand canyon and the rift in east Africa are some of the best examples. Usually, chasms get filled with water when they get big enough unless they form in the desert. The biggest one would be the Atlantic ocean.

[xpian]

Moon of a Large Gas Giant
I think most physicists believe this to be entirely possible. A gas giant can get very large before it ignites to form a star. Some estimates are that it would take TEN Jupiter masses before nuclear fusion could ignite. So Jupiter is already huge, but you can get a lot bigger and still be a gas giant planet. A big gas giant can have very large moons: Ganymede is larger than Mercury or Pluto. Something the size of Mars or Earth could easily orbit a large gas giant.

As for radiation, the inhabitants of such a moon would be even better off than they are on Earth. Jupiter has a massive magnetic field that deflects a great deal of solar and interstellar radiation. And an earth-size moon could easily have its own strong magnetic field adding to that protection. Even Ganymede has its own magnetosphere.

As for warmth, it's true that Jupiter is quite a ways out in the solar system, and thus gets a tiny fraction of the solar radiation the Earth does. This means that Ganymede, Callisto, and Europa are all frozen solid on the surface. But we now know that jupiter-like gas giants don't need to be far from their star. Our planetary surveys have shown many "hot jupiters" orbiting nearby stars at many distances, from the baking zone of Mercury and Venus out to the goldilocks zone (liquid water) of Earth. It's entirely possible to have an inhabited gas giant moon at a comfortable range. Plus, the gas giant itself is likely radiating some heat. Jupiter does this: it puts out more heat into the universe than its taking in. We're not entirely sure why...we know it's not fusion going on, but must be some other process deep within the planet.

And while its true that Io is super hot due to jupiter's tidal forces heating it up, that wouldn't necessarily happen to any inhabited moon. It's all a function of the orbital distance.

Atmosphere is no problem for such a moon. Titan, for instance, has a very thick atmosphere with wind, rain, etc.

[BlackChakram]

I can contribute some details here as well.

Moon of a Larger Gas Giant
While gas giants do have huge magnetic fields that deflect a lot of radiation, they also create tons. Jupiter's moon, Io for example is in a radiation belt strong enough to give a human a lethal dose in a very short timespan. I can elaborate on xpian's ideas about heat generation as well. Jupiter generates heat because it's still contracting from its formation. That gravitational energy is radiated out slowly. However, this energy does little to warm anything except Jupiter itself.

Additionally, unless your moon is a captured asteroid, it's almost guaranteed to be composed primarily of ice. Most of the gas giant moons are. This has advantages, though. The tidal forces that stretch Io are also suspected to be stretching Europa and Callisto, possibly creating a liquid ocean beneath a surface of ice. Sooo, if you want an aquatic race, gas giant moons are excellent. But xpian is right. You could easily have something like an earth-sized planet an acceptable distance from a gas giant to support life. With a thick enough atmosphere, you could even keep it relatively warm.

Twin Earths
Entirely possible. In fact, Earth and its moon are considered to be a "double planet" because they're so close in size (astronomically speaking). This likely would cause tidal locking, but wouldn't necessarily mean some parts of each planet get no sunlight. The moon is tidally locked to earth, but because its axis is tilted, it doesn't create an eclipse every time it orbits.

Axial Tilting Periodical Movements
Yes. Theoretically possible. What you're describing is an effect called "precession". Earth does it at a small angle on a 50,000 year cycle. Think of it like a spinning top that starts to wobble. We don't see this mess with the seasons on Earth because that 50,000 year period is far slower than the 365 day period for a year. But IF you had a planet that was precessing much faster than it was orbiting, you could get some wonky effects. However, any planet precessing that fast would sort of even itself out. So the only way you could do this would be to bend reality and have the planet precess very quickly but have a very far orbit. Science fiction, right!

I can add a few other crazy ideas, too.

Interesting Exosolar Planets
Some of the planets we're theorizing have some crazy properties. Planets tidally locked with their parent stars so that one side is permanently dark, the other bright. This creates turbulent wind patterns at the terminator (the border between light and dark). You could then have a planet with permanent areas of twilight with permanent violent storms.

We've also theorized that there are "carbon planets" composed almost entirely of carbon. These planets could literally have volcanoes that erupt diamonds.

Rogue Planets
It's hardly impossible to have planets that get flung away from their parent stars and sent into deep space. These rogue planets would literally just wander between stars, almost permanently dark and frozen. But you could have life living deep under the surface, surviving on heat radiating from the core. I think there was a Star Trek Voyager episode that did something with a rogue planet.


If your axial tilt is stuck vertically (which, if I understand what you're getting at would mean NO tilt), then you pretty much won't have seasons. You'll get a planet with weather the same all year round. Farther north you go, the colder it gets, but that'd be about it. If your trajectory is elliptical enough, you will get seasons, but they'll affect the entire planet at once, rather than the north-south hemisphere opposites we get on earth.

[Trollface13]

well if earth had no moon the orbit would destabilize and all tides would sieze but worst of it is the weather stops then tectonics stop and that means te carbon cycles stop and eventually life on earth as we know it would stop and our blue ball will turn red like mars.... lack of a moon also gives lack of a magnetic field irradiating the planet killing almost all life on the surface.

if earth had 2 moons however its a different story. the extra moon would cause some extreme conditions such as larger hurricanes and vast extremes in wind speed and dust storms it does strengthen the magnetic field but it would also mean more earthquakes and volcanic activity. but really it depends on the moons mass. if its larger than our current one it could rip our planet apart but if it is smaller it would not be so bad.

now earth has had ice ages before and the correct term for tropical age is "Hot House Age" and we had alot of those during the cambrian, carboniferous, and the cretacious/eocene times the Eocene being completely iceless the Eocene epoch was so hot in fact that germany and antarctica were covered in jungles and canada was covered in swamps.

on alien worlds however in terms of climate can vary on atmospheric density and gas composition. take pandora from avatar for instance its atmosphere contains high carbon dioxide levels nearly 20 percent to be exact that is why humans wore masks on the planet as carbon dioxide is toxic to us.... however alternate biologies of the lifeforms on pandora allow the existance of complex life just as long as the 4 biochemicals exist on the planet(oxygen, nitrogen, carbon, hydrogen). however he same climate conditions can be created with an atmosphere like earth just by increasing atmospheric density and/or distance from its parent star. thing is if you want a jungle world in the solar system. reduce the density of venus's atmosphere and filter the carbon and sulfur out and maybe add a few large asteroids as moons you would get the same results as cretacious earth. the reason why the pressure is so high on venus is because of the heat it generates from the surface and sunlight assisted with the carbon compounds in the atmosphere as well as the higher density. but take away one or two of those and you can make many different conditions but maybe not all earth like unless you add a few things too.

as for gravity..... well watch james camerons avatar and look at the trees and the na'vi, they are frakking huge. you know why? because pandora has similar mass to venus. meaning less gravity. if a person is born on the moon and is raised there they could reach about 6 feet at age 10. if a person is born on mars however they would only be around 4-5 feet at age 10.

[Trollface13]

There is a possible way a planet can host earthly life in the cold zone of a star system..... A gas giants moon if close enough to its parent planet can give off geothermal heat in the atmosphere via volcanic activity but the thing is it has to contain ice in the first place for it to work. not all life depends on sunlight to live deep oceans geothermal vents proved that. just imagin humanoids that use nocturnal vision to see walking in a dark Chemosynthetic forest. the area filled with hydrothermal oceans and geothermal hot spots. the normally toxic chemicals wouldnt be a problem because of the chemosynthesis the strange plants use. it would be very very dark like an eternal night so humans would need nightvision goggles. But it is indeed possible that such a place exists.

[Trollface13]

Thanks for the correction.... i need to update my knolege.... turns out my info was incorrect i thought the moon was vital to earths survival but i guess i was informed wrong.

[Trollface13]

however i do have a question..... can a city planet like coruscant even exist? or would you need to keep some natural environment in a few places so the place doesnt kill itself?

[xpian]

Olympus Mons on an earth-like planet

Mars's Olympus Mons (and the three other Tharsis Montes) are very big volcanic mountains. They bulge from the surface to a ridiculous degree--Olympus Mons is three times the height of Mt. Everest, and that's on a planet that's half the size of Earth. Gravity? of course there's gravity. It would be a bit less up there, but not so much that you'd notice. Any point that's further from the planet's center of mass, including the top of Mt. Everest, has less gravity. It's just negligible. I think the confusion comes from the idea that there's zero G just a little further up, in space...which isn't true. There's gravity up there as well. The reason people on the ISS are weightless isn't because the Earth's gravity has stopped, it's because they are in free fall (they are orbiting the planet so swiftly that they are continuously "falling" around it.) You can't be in free-fall whilst standing on a mountain top--even one as tall as Olympus Mons.

Air would be very thin up there, however, as Azelor has mentioned. Only enough for the tiniest life forms, and certainly not enough for any animals like humans. That's if you're being very accurate with your planet's atmosphere.

The other thing about Olympus Mons to remember is how SHALLOW the slope of the mountain is. Seriously. You'd start walking up one side of the mountain and you wouldn't really be able to see the top. It would just be a gently rising slope in front of you. You'd keep walking, day after day, trudging over lava flows, and the air would just get thinner and thinner as you got higher up. Maybe the winds would get really nasty at certain levels, but you still wouldn't see the top of the mountain--just more slope rising in front of you. And you'd die long before you reached the top.

Which is not to say that extreme verticality is impossible. There are cliffs on Mercury that are kilometers high. It's conceivable that you could have sharp, tall, spiky mountains taller than the Himalayas on an earth-like planet. Extreme materials, extreme geology, extreme plate tectonics...it's certainly possible to have crazy-tall mountains that you *would* see the tops of as you were climbing them...as you were dying on the slopes of them...