What Are Some Interesting Planet Concepts from Sci-fi?

[Rakaydos]

*cough*

http://upload.wikimedia.org/wikipedia/en/7/71/Ringworld(1stEd).jpg

Difference of scale. Ringworld is 1 AU in radius, wheres a Culture Orbital (which the Halo is explicitly modeled on) has a radius "such that 1 rotation per day gives a 1g effective gravity." No Shadow squares, no solar-flare-superlasers, and no scrith required.

If we're bringing up Canyon, we may as well bring up Plateau and Jinx. One's effectively Venus, but with a single mountian range up to the 50km "habitable" zone venus has, and the other is a supermassive moon orbiting close enough to it's parent supergiant's roche limit to become egg shaped, the poles sticking entirely out of the atmosphere.

[cantab]

A fairly normal planet, but Nightfall is set in a sextuple star system. The orbits are such that there is always at least one sun above the horizon, except when there's a once-in-a-millenium solar eclipse.

The real world is scarcely less strange than fiction. Take Kepler-70b, thought to have been engulfed by its star during the red giant stage but survived to orbit its star once every six hours, so close that the planet's surface is hotter than our own Sun.

[meve12]

Technically, that's a space station.

That's like saying the sun's a yellow dwarf.

Technically correct, but looking at it makes you say holy molly.

[meve12]

Canyon from Larry Niven's Known Universe series is interesting. A planet with an incredibly thin atmosphere, but with a deep, deep canyon in which the atmo is thick enough to be habitable. Pressure suits are required on the surface but not in the canyon.

Notably, said canyon was formed by disintegrater generated lightning.

[Sky_walker]

Not really a sci-fi, but.... they tend to be more interesting than sci-fi planets: http://www.space.com/159-strangest-alien-planets.html

[Scotius]

"Black planet" from the "Andromeda Nebula" novel by Russian author Efremow. It's a massive rocky world, orbiting a star that is radiating almost completely in infrared. Since there is almost no visible light (even stars are dimmed to nothing by thick atmosphere) lifeforms are uniformly black and eyeless.

[-Velocity-]

Difference of scale. Ringworld is 1 AU in radius, wheres a Culture Orbital (which the Halo is explicitly modeled on) has a radius "such that 1 rotation per day gives a 1g effective gravity." No Shadow squares, no solar-flare-superlasers, and no scrith required.

Can't they do any basic math?

a = w^2*r

w = angular rate

= 2*pi/(24*3600) = 7.27e-5 rad/s

.. r = a/w^2 = 9.81/(7.27e-5 rad/s)^2 = 1.85 million km.

Oh... but what does "day" really mean?

If we're bringing up Canyon, we may as well bring up Plateau and Jinx. One's effectively Venus, but with a single mountian range up to the 50km "habitable" zone venus has, and the other is a supermassive moon orbiting close enough to it's parent supergiant's roche limit to become egg shaped, the poles sticking entirely out of the atmosphere.

I don't think that makes sense. A planet that is egg-shaped due to tidal forces, and tidally locked, should be in hydrostatic equalibrium, and the atmosphere would cover everywhere.

[Rakaydos]

Can't they do any basic math?

a = w^2*r

w = angular rate

= 2*pi/(24*3600) = 7.27e-5 rad/s

.. r = a/w^2 = 9.81/(7.27e-5 rad/s)^2 = 1.85 million km.

Oh... but what does "day" really mean?

Actually, it depends on what race is building it. If your race wants a longer day, but higher gravity, that race's orbtals will be larger than a race that likes shorter days and less gravity.

I don't think that makes sense. A planet that is egg-shaped due to tidal forces, and tidally locked, should be in hydrostatic equalibrium, and the atmosphere would cover everywhere.

IIRC, it migrated outward over the aeons, after the crust had solidified. though that might have been retcon. Larry Niven's Known Space is ANCIENT.

[magnemoe]

Actually, it depends on what race is building it. If your race wants a longer day, but higher gravity, that race's orbtals will be larger than a race that likes shorter days and less gravity.

or you simply use shades and reduce the diameter and increase spin so its something who is easier to build.

Unlike ringworld it would be an obvious space station anyway, yes you could get an stable ecosystem, but you would want extra power anyway.

IIRC, it migrated outward over the aeons, after the crust had solidified. though that might have been retcon. Larry Niven's Known Space is ANCIENT.

Yes. most of the strange know space planets are impossible because of hydrostatic pressure. Mars has its high volcano as its small.

[-Velocity-]

Actually, it depends on what race is building it. If your race wants a longer day, but higher gravity, that race's orbtals will be larger than a race that likes shorter days and less gravity.

My guess is 1g is fairly universal for Earth-like inhabited worlds, within -20% to +50% or so. Assuming a constant density, the surface gravity of a planet increases by the cube root of its mass. We don't know for sure that super-Earths aren't habtitable, though an overly thick atmosphere seems to be likely. You could end up trapping far too much water and gases. That doesn't mean that all super-Earths have to be inhospitable, that just means that a lot of them probably would be. However, we could end up being surprised on this account.

At the other end of the spectrum a planet much less massive than Earth will cool off too quickly, losing its geodynamo (magnetic field). It will have a hard time holding onto an atmosphere, and plate techtonics will quickly shut down.

A 0.5 Earth mass exoplanet, which is supposedly pretty far on the low end of habitiablity predictions, has a surface gravity of 0.8g, and a 4 Earth mass exoplanet has a surface gravity of around 1.6 g. Again, that's assuming the same density as Earth, but that seems fairly reasonable for ballpark assumptions. These ballpark assumptions can be used to make some other reasonable guesses- for example, alien life adapted to 3g is not likely to exist (or at least, be anywhere near as common as lower-gravity lifeforms like us), as that requires a terrestrial planet with a mass of 27 Earths, which puts you firmly into the range of small gas giants.

IIRC, it migrated outward over the aeons, after the crust had solidified. though that might have been retcon. Larry Niven's Known Space is ANCIENT.

Retconed by fans or Niven once it was pointed out that his planet did not make physical sense?

Edited November 11, 2014 by |Velocity|

[KerikBalm]

or you simply use shades and reduce the diameter and increase spin so its something who is easier to build.

Unlike ringworld it would be an obvious space station anyway, yes you could get an stable ecosystem, but you would want extra power anyway.

A fast spin would result in fast day/night cycles, unless you have the plane of the ring perpendicular to the incoming light, but then you're in perpetual twilight

[Thesla]

Theres a really cool concept, its not a planet, gut a great mass of gasses orbiting a star, the inner layer is habitable. It is basically a freefall world, where all the animals and plants evolved in zero g. It shows up in the book The Integral Trees, plus in here: http://abiogenisis.deviantart.com/art/The-Shadow-of-the-Sun-58459821

[magnemoe]

Theres a really cool concept, its not a planet, gut a great mass of gasses orbiting a star, the inner layer is habitable. It is basically a freefall world, where all the animals and plants evolved in zero g. It shows up in the book The Integral Trees, plus in here: http://abiogenisis.deviantart.com/art/The-Shadow-of-the-Sun-58459821

It require an pretty special setup who is explained in the book.

You need an old and cold neutron star, you need an sun in orbit around it and an sort of super venus with lots of atmosphere in, close orbit to the neuron star so close the atmosphere will leak out, however the atmosphere would end up in orbit around the neutron star, if it drift to higher or lower orbits it would be pulled back down by the planet.

Gas by itself would not stay in an stable orbit.

Not sure if this would work and it would anyway be very unlikely.

One thing who will work is that an moon in orbit to an gas giant will get help of it to keep its atmosphere, Titan would loose its if it was not for Saturn.

So if you want an low gravity world make it an moon.

[Rakaydos]

Retconed by fans or Niven once it was pointed out that his planet did not make physical sense?

This is the author who wrote a story about "the cold side of mercury", and before it was published NASA's probe discovered mercury isnt actually (quite) tidelocked to the sun. He offered to return his writer's fee for writing known bad science in his science fiction.

[vger]

Gas by itself would not stay in an stable orbit.

At the right temperature it could. It wouldn't be a place we'd want to visit though.

[Soda Popinski]

Rogue planet. There's a good chance most planets out in the Universe have been ejected from their parental solar systems. Imagine a planet not orbiting any star. To make it interesting, lets say it's warmed by radioactive decay at the core leading to vulcanism or some kind of chemical energy to sustain life on the surface.

Another idea. If the Universe is infinite, and such there are an infinite number of Earths, and anything physically possible (even if unlikely) has happened somewhere in the Universe, then out there, I'm Batman.

[sndrtj]

* The Juggler planets from Alastair's Reynolds' Revelation Space universe; not weird in physical sense (ocean planets), but with thinking single-celled organisms which can absorb human conciousness when someone swims for too long in the seas.

* The Shellworlds from Iain M Banks' Matter. These worlds are artificial planets which consist of concentric rings in the interior (like a planetary matrushka doll), each level of which is inhabited by civilizations in several developmental stages (and lit by mini-stars lining the ceiling of each level)

* Charon in 2312 by Kim Stanley Robinson. Turned into a massive spaceship for exiled androids, en route to nowhere.

[CaptRobau]

Here's a whole bunch of planet concepts that a guy with too much time on his hands came up with to challenge the normal preconceptions of how life-bearing planets could form.

http://www.worlddreambank.org/P/PLANETS.HTM

He's working on a tide-locked planet right now, it's all pretty interesting.

That's a really cool site. I just love that basic, Geocities look, on sites that are relatively recently updated. Shows that they care more about the info, instead of just making something look nice.

[magnemoe]

That's a really cool site. I just love that basic, Geocities look, on sites that are relatively recently updated. Shows that they care more about the info, instead of just making something look nice.

Yes, and really like the variation in planets.

[Bill Phil]

The real possibility of a habitable land planet( less water than earth on surface) does exist. It actually has larger habitable zones because they can have high albedo's.

[GregA]

Galactic scale extinction events, thus explaining the Fermi Paradox.

[magnemoe]

The real possibility of a habitable land planet( less water than earth on surface) does exist. It actually has larger habitable zones because they can have high albedo's.

The site over has multiple.

from

http://www.worlddreambank.org/S/SERRANA.HTM

who is a bit dryer than earth

to

http://www.worlddreambank.org/T/THARN.HTM

who has 1% but is still an decent place, main problem is the low air pressure.

[Armchair Rocket Scientist]

The site over has multiple.

from

http://www.worlddreambank.org/S/SERRANA.HTM

who is a bit dryer than earth

to

http://www.worlddreambank.org/T/THARN.HTM

who has 1% but is still an decent place, main problem is the low air pressure.

This one counts as well: http://www.worlddreambank.org/C/CAP.HTM

For that matter, there's Siphonia (AKA Earth with 90% of the water removed).

http://www.worlddreambank.org/S/SIP.HTM

[problemecium]

I'll be the first to say Coruscant.

The concept, anyway. The way it ended up getting portrayed in the Star Wars movies was, after reading up on the original idea, underwhelming. If a civilization is going to get so grossly overindustrialized that they cover an entire planet in buildings, well... that's a lot of buildings. They say a person on Coruscant could live his or her entire life without ever actually touching the ground - just hopping from building to building in skybridges or aircraft. But in those movies, well... the city wasn't much more grand, at least vertically, than our regular old Earth cities. In some cases ours exceed it: in Hong Kong, there's a borough where the skyscrapers are packed so close together that even in broad daylight everything is in a twilight-like shadow.

But if you imagine Coruscant done per the original idea, with forests of buildings piled atop other forests of buildings, complete with a labyrinthine underbelly where the structures weave together like a mangrove and form artificial caverns, it's pretty awesome.

On another note, for the open-minded among you (minor adult content warning), have a look at Felarya. If you can get past all the magic and references to "dimensions" (misnomer), it's a rather compelling concept. Long story short, it's a world that is enclosed in something somewhat akin to an Alcubierre bubble, with some kind of mechanism that causes wormholes to show up periodically that connect it to a variety of other worlds, contributing to a large diversity of inhabitants and wildlife.

Edited November 15, 2014 by parameciumkid

[Red Iron Crown]

I'll be the first to say Coruscant.

The concept, anyway. The way it ended up getting portrayed in the Star Wars movies was, after reading up on the original idea, underwhelming. If a civilization is going to get so grossly overindustrialized that they cover an entire planet in buildings, well... that's a lot of buildings. They say a person on Coruscant could live his or her entire life without ever actually touching the ground - just hopping from building to building in skybridges or aircraft. But in those movies, well... the city wasn't much more grand, at least vertically, than our regular old Earth cities. In some cases ours exceed it: in Hong Kong, there's a borough where the skyscrapers are packed so close together that even in broad daylight everything is in a twilight-like shadow.

But if you imagine Coruscant done per the original idea, with forests of buildings piled atop other forests of buildings, complete with a labyrinthine underbelly where the structures weave together like a mangrove and form artificial caverns, it's pretty awesome.

Makes me think of Trantor, Isaac Asimov's capital planet of the Galactic Empire. The land surface of the planet was entirely enclosed in arcology-like domes and housed forty-five billion people, and it was fed by twenty agricultural planets with food shipments delivered by an armada of freighters.

Another interesting one is the puppeteer home planet from Niven. Highly developed and part of a unique astronomical formation.