All Hypothetical; but i need some help

[xPooLSharKx]

First off, I am a "writer" and I am currently working on a project of mine; all personal and for my enjoyment. But i have questions and I will give a brief break down. I want a planet that is half ice and always dark, and half ... well regular habitable planet (night and day, plants, animals, the whole 9) and the planet is always like that. The only thing i could come up with is a symbiotic orbit of planet and moon. Even still though the "always dark side" of the planet would have atleast some sunlight depending on how big the planet is, how big the moon is, how far away the moon is. Someone also suggested that the planets rotation stop, but that doesn't make sense to me because 1/2 the year i'd be dark and 1/2 the year would be light for both sides... :sigh: um... can anyone help me put my thoughts in a line or tell me how it actually would be, or how could i explain it to where a planet would be, to the way I want it.?.?.?.

 

[SteveCNC]

well I suppose that if the planet had a large tilt say 70 degree and it had a precession period that was equal to it's year the side tilted away (south pole) would never get direct sun and the side that gets sun (north pole) would have a pretty steady temperature . There wouldn't be much darkness on the sunny side but some in places .

 

[xPooLSharKx]

I'm guessing a moon doesn't have an irregular orbit pattern, such as fast to slow or vise versa. Is it always constent? Is it also possible to have a moon almost as large as the planet? Just exploring some options here, letting the creative juices flow...

 

[yevaud]

Here's a thought: make this a large moon (certainly large enough to possess sufficient gas pressure for people to live on), which is tidally locked to a Gas Giant.

 

[kelvinzero]

By the way,

When that person suggested that the planets rotation had stopped, they almost certainly meant it had become tidally locked to something else, such as the sun. This would mean one side was always day, the other always night, and boundary always twilight.

This is quite common. For example the moon is tidally locked to the earth, and for a while people used to think that Mercury was tidally locked to the sun.

Someone famous (maybe Alfred E Bester?.. whoever wrote "Tiger Tiger") wrote a story set in the far future where the earth had become tidally locked to the sun.

Hey, just thought of a way that might work for you:

Suppose the planet is in orbit around some massive star, or even in orbit (at some fantastic distance) around something like a quasar. The point is it has a massively long "year" eg thousands or billions of years respectively. In this case you would have an area that has been dark for thousands (or billions) of years and ditto for the bright side, but with the right axial tilt the twilight area could oscillate daily between mid-morning and late evening.

 

[JasonChapman]

What are you guys doing for goodness sake!

I'm a writer too, and I'm working on a novel, Smersh and Jim48 will vouch for me because I have asked them to read part of it.
Not once have I thought about coming on here and asking for help, going out and doing your own research is half the fun and interest of being a writer.
Science Fiction is probably one of the hardest subjects to write because of the amount of research you have to do. I'd feel guilty if I came on here and said hey guys I need help writing a book.

There are some extremly intelligent people on space.com who could write your book for you probably, but you seriously need to consider the consequences before you ask for help.

Good luck with your writing.

 

[kelvinzero]

I think there are a number of SF writers who would have benefited from coming here first

In answer to your original question, we are brainstorming. Its fun.

Really I wouldn't worry that we are going to write anybodies book for them by brainstorming a few ideas. There is a saying that goes along the lines of "plot is the last recourse of the bad writer". What this is trying to say is that it is not plot that makes a good story, it is whether or not you care about the characters. Plot is just things that happen in sequence.

Ever seen someone post a "great idea" and they just want someone to write it for them? The fact is a good book has good ideas on every page, and every page serves a purpose. To think you can just pour out a book given an idea shows they really don't have a clue.. and usually these people's great ideas sort of suck also

The only thing that brainstorming some ideas would do, is prevent losing a percentage of the audience who can spot astronomical bullocks. Some people just wouldn't care about the accuracy.

 

[eburacum45]

Here's a couple of planets which are tidally locked from Orion's Arm
http://www.orionsarm.com/eg-article/47a683c98fd29
http://www.orionsarm.com/eg-article/48fa66f687117

and one with a central hurricane
http://www.orionsarm.com/eg-article/4922e9afcd478
You can't really have a planet with one hemisphere dark and the other hemisphere with a day-night alternation; even if one side is frequently eclipsed by a large moon or gas giant, it will receive sunlight for most of the day.

 

[CAllenDoudna]

I once considered a somewhat similar situation in which a planet-sized moon orbited a gas giant and it's day was maybe a year long. Evening before sunset would be October and after sunset it would be November. Dawn would be March before sunrise and April after sunrise. The winter would have been Arcticlike while the summers would have gotten incredibly hot.

 

[flyer456654]

Ok, Perhaps i'm completely wrong about the physics, but couldn't this be possible.

Have an earth sized planet, in the habitable zone, that has a slow rotation. Still fast enough to develop a magnetic field but slow enough to essentially allow one side always facing the sun (simulating tidally locked but not being tidally locked). Than have a very large moon (or even a small moon that is very close) that revolves around the planet. or better yet, 2 moons (perhaps a split planet from a collision). These moons would rotate at the tropics and on opposite sides of the planet (thus being able to avoid the other's gravity). If the moons were large enough to eclipse the sun from the equator to the poles, it would allow for a relatively nice night/day cycle just at opposite times (northern hemisphere is in daytime while southern hemisphere is at night)

There is still a MAJOR issue with this though. The dark side of the planet would be cold enough to freeze the atmosphere. There would have to be major techtonic movements (possibly caused by the moons) or volcanic explosions constantly raging to keep that side warm enough to foster an atmosphere. Don't know how a planet would manage to achieve a hot enough temperature to sustain an atmosphere on the dark side....more brainstorming.

 

[MeteorWayne]

Have an earth sized planet, in the habitable zone, that has a slow rotation. Still fast enough to develop a magnetic field but slow enough to essentially allow one side always facing the sun (simulating tidally locked but not being tidally locked).

Ummm, that IS tidally locked, and too slow a rotation. That's what one side facing the sun means...

 

[flyer456654]

Sweet I got to sound like an idiot lol But couldn't an impact of that size at the right location slow down the rotation and force it to become tidally locked that far away?

 

[MeteorWayne]

That's one way (unlikely but possible), but once it's got the same face to the star all the time, it will become locked due to gravitational distortion of the planet. An impact could be the proximate cause of the rotation slowing to that point, though there are others.

 

[flyer456654]

Wayne,
I still think there is a major issue with this planet configuration and I default to your knowledge for how to fix this problem. Wouldn't having one side always dark, make it so cold that it would freeze the atmosphere? Wouldn't this mean that there would be no gasous atmosphere? I suppose (and I don't know this for sure) that the gravity from the moon might cause enough tidal forces to generate enough heat to form a gasous atmosphere on the one side (aka titan's possible liquid ocean below the surface). How do you think this could happen?

I love hypothetical conversations.

 

[kelvinzero]

This is not a hypothetical conversation. You are actually having it

My guess is that not all the atmosphere would have to end up frozen on the dark side. Heat would still be transmitted from the warm side to the cold side via (a) the air movement itself and (b) through the wamth of the planet. If the icecap of frozen atmosphere were deep enough, its temperature deep beneath the surface would have more in common with the average of the entire planet (assuming the core itself were not hot) that with the super-cold surface. This average temperature would be well above the freezing point of the gasses so even if the surface was frozen gas, there would be continual volcanic eruptions from the warmed gasses underneath.

Thats my logic anyway.

 

[CAllenDoudna]

or better yet, 2 moons (perhaps a split planet from a collision). These moons would rotate at the tropics and on opposite sides of the planet (thus being able to avoid the other's gravity).

I'm no expert on orbital mechanics, but I believe that would be an extremely tricky stunt to pull off. I know it's a favorite of science fiction writers (usually a Second Earth on the opposite side of the Sun), but the ballancing act necessary for this to work is nearly impossible. Much easier would be six moons (or six planets), each in the L-4 / L-5 points (Lagrangian libration points?) of the one on either side. That would produce a naturally stable orbit with each planet held in place by its neighbors. The only way two moons (or planets) can share the same orbit and still be stable is if they rotate about each other as a double planet.

So theoretically the maximum number of Earths we could have would be 12: six pairs each in the L-4 / L-5 point of the neighbor pairs on either side. If these Earths were about four time the distance from each other as the Moon is from Earth then they would have just slightly less gravitational pull on one another as the Moon has on us. I suspect pairs of planets would produce trickier Lagrangian points than single planets.

 

[eburacum45]

Much easier would be six moons (or six planets), each in the L-4 / L-5 points (Lagrangian libration points?) of the one on either side.

multiple planets in the same orbit are best described as Klemperer Rosettes.
See this interesting page about the concept
http://burtleburtle.net/bob/physics/kempler.html

You are quite right, however; two moons can't remain opposite each other in an orbit for a significantly long period.

 

[bob_jenkins]

I liked the suggestion of a habitable planet tidally locked with a gas giant. Have the plane of its orbit aligned with the plane of the gas giant's orbit about the sun, have it close enough that the gas giant eclipses the sun during the hours near noon, and have the orbit around the gas giant take about a day. Not having sunlight in the middle of the day brings the temperature of the giant-facing side down, but having a gas giant filling the sky every night (with the gas giant facing the sun) will bring the giant-facing side's temperature up. I don't know if the giant-facing side would be hotter or colder than the other side on average.