# Random Day/Night Length



## shangrila (Aug 26, 2012)

This is an idea I had recently, so I thought I'd put it up here and see what people think and, ultimately, if it's worth pursuing.

Basically, it's as the title says; days and nights are random in length. They could last for a few earth days, a week, or only a few hours (that would be the minimum). A group of people do their best to predict it but it's more of an educated guess than an actual prediction, like weather forecasting in real life.

So my question would be; is this idea somewhat plausible to you? Or is it just too stupid to bother with?


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## Astner (Aug 26, 2012)

The right answer is: If it fits the story.

From a scientific perspective it could work if you had a number of stars orbiting each other and planets, specifically the earth, leaving and entering new orbits -- orbits more attuned with the planets own rotation would make the nights and days longer -- around these stars.

In a thief-like setting it could be amazing.


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## Benjamin Clayborne (Aug 26, 2012)

I wouldn't try to explain how it works if you do this, although keep in mind that if a daytime period lasts only a few minutes, the sun is literally racing across the sky. You could watch the shadows move.

Astrophysically, there's no plausible way to make this happen; changing the rotational speed of a planet requires colossal amounts of energy that would probably rip it apart. If you do do this, I would just make it an accepted fact of the world and not dwell on it.


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## Astner (Aug 26, 2012)

The only thing that's of significance is the angular velocity relative to the orbit. So if the orbit change, as in you have a number of celestial bodies to occasionally tear the planet from one orbit to another then that would present a new day and night cycle.


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## shangrila (Aug 26, 2012)

Thanks for the replies.

I wasn't thinking of a scientific reason. My first idea was of a realm, something that wasn't a typical planet and actually had a completely random rising of the sun and moon. The sun and moon would actually be two warring gods; whoever had the upper hand at the time would have their object (the sun or moon) dominate the sky.


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## Penpilot (Aug 26, 2012)

It's a cool idea, and I agree, with Benjamin, just state it as fact and get on with the story.


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## ShortHair (Aug 27, 2012)

It might work if you had several objects in the sky, some giving off light, the others occluding light. In other words, "night" would only be an eclipse involving two or more objects on (apparently) random paths. The star system might have several suns and the planet several moons. Another possibility is one sun and an asteroid belt very close to the planet (but outside its gravity well).


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## Astner (Aug 27, 2012)

ShortHair said:


> It might work if you had several objects in the sky, some giving off light, the others occluding light. In other words, "night" would only be an eclipse involving two or more objects on (apparently) random paths. The star system might have several suns and the planet several moons. Another possibility is one sun and an asteroid belt very close to the planet (but outside its gravity well).


Good idea, cosmic dust could work well. Assuming he's going for a scientific explanation.

The point is, it's not scientifically impossible so it won't ruin the suspension of disbelief even if he decides not to explain it.


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## Jared (Aug 27, 2012)

shangrila said:


> Thanks for the replies.
> 
> I wasn't thinking of a scientific reason. My first idea was of a realm, something that wasn't a typical planet and actually had a completely random rising of the sun and moon. The sun and moon would actually be two warring gods; whoever had the upper hand at the time would have their object (the sun or moon) dominate the sky.



I agree with Benjamin Clayborne in that you can't explain it scientifically. So don't try.

About his in-sky and shadow motion comment...Is the planet round? Are day and night global? Where does the sun go during the night?

Scientifically, the moon is bright because it's reflecting sunlight. Will your moon be emitting its own light, or still reflecting sunlight from somewhere else?

Regardless of the mechanics of the sun and moon, you might think about the effect on temperature and weather.


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## Astner (Aug 27, 2012)

Jared said:


> I agree with Benjamin Clayborne in that you can't explain it scientifically. So don't try.


Exactly how is my model unscientific by any means?


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## Benjamin Clayborne (Aug 27, 2012)

Jared said:


> I agree with Benjamin Clayborne in that you can't explain it scientifically. So don't try.
> 
> About his in-sky and shadow motion comment...Is the planet round? Are day and night global? Where does the sun go during the night?
> 
> ...



Not to mention its effects on culture... and sleep cycles. People probably wouldn't put much stock in scheduling things in advance that required daylight, since you never knew how many "days" away something was. Timekeeping would probably be a huge deal, since you can't use a common natural phenomenon like the sun to tell time. Thick curtains would be a highly desired item, to block out sunlight when you needed to sleep and it happened to be daytime.


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## Benjamin Clayborne (Aug 27, 2012)

Astner said:


> Exactly how is my model unscientific by any means?



Shifting planets into different orbits like that would most likely result in tidal forces that would destroy them. Any such system would still need to be fairly regular; you might see changes in day duration over the course of several years. A system where one day is four hours long and the next day is twenty hours long would be so chaotic that any planet in it would be quickly torn apart, or end up so close to a star that the surface temperature would be in the thousands of degrees.

Also there's the fact that rapidly and drastically changing the rotational speed of a planet will also tear it apart. The amount of energy involved in a planet's rotation is _huge_. Earth's rotational energy is 2.138Ã—10[sup]29[/sup] J. (By comparison, the energy of a 1000 kg car moving at 44 m/s (~100 MPH) is about 968,000 J. The planet has 220,867,768,595,000,000,000,000 times as much energy.) Any force that could change that substantially on anything less than a geologic timescale would rip the planet in half.


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## Jared (Aug 27, 2012)

Astner said:


> Exactly how is my model unscientific by any means?





Astner said:


> The only thing that's of significance is the angular velocity relative to the orbit. So if the orbit change, as in you have a number of celestial bodies to occasionally tear the planet from one orbit to another then that would present a new day and night cycle.





Benjamin Clayborne said:


> Any such system would still need to be fairly regular; you might see changes in day duration over the course of several years. A system where one day is four hours long and the next day is twenty hours long would be so chaotic that any planet in it would be quickly torn apart, or end up so close to a star that the surface temperature would be in the thousands of degrees.
> 
> Also there's the fact that rapidly and drastically changing the rotational speed of a planet will also tear it apart. The amount of energy involved in a planet's rotation is _huge_. Earth's rotational energy is 2.138Ã—10[sup]29[/sup] J. (By comparison, the energy of a 1000 kg car moving at 44 m/s (~100 MPH) is about 968,000 J. The planet has 220,867,768,595,000,000,000,000 times as much energy.) Any force that could change that substantially on anything less than a geologic timescale would rip the planet in half.



To support Benjamin, Wikipedia puts the Moon's day-lengthening effect at 31 milliseconds per century.

Additional issues are that tidal forces fall off strongly with distance. If something were capable of doing this, it would be close (see: satellites, co-satellites, co-orbiters, or planet the object is a satellite of). And it would be relatively massive.




ShortHair said:


> It might work if you had several objects in the sky, some giving off light, the others occluding light. In other words, "night" would only be an eclipse involving two or more objects on (apparently) random paths. The star system might have several suns and the planet several moons. Another possibility is one sun and an asteroid belt very close to the planet (but outside its gravity well).



Any object in the sky bright enough to make it seem like day would have to be a star in the star system. If they operate under the laws of celestial mechanics, they would have periodic cycles. They would not be random, as the OP requested. The only stable orbits (that we have been able to find) are those where a planet orbits one star closely and the others are distant, or the planet orbits closely-packed stars at a distance. For the former, the length of day would be be a function of time of the year and of year. For the latter, the length of day would be a function of time of the year (like on Earth), but would not be a 50-50 split at equinox at the equator.

Asteroids are too small to occult the sun. Even if they could (like our Moon does), occultations are short and periodic. They are also not visible over more than small regions of the planet's surface.




Astner said:


> Good idea, cosmic dust could work well.



Two issues with this one.

First, dust densities are extremely low: optical depths for large structures _within the solar system_ are below ~10^(-5). If you include molecules, then Enceladus' plume could occult ~10-15% of the light in a small region. But 10-15% in a small area is not night (by any definition). [The images of dense nebula and such appear opaque because they are huge-huge-huge, not because they dense.]

Second, you would need a way to create a large-scale structure that is unstructured. In the solar system, Enceladus', Io's, and Pheobe's dust rings are structured. Dust columns created by Saturn's and Jupiter's magnetospheres are very narrow and structured (mostly, I think). Dust spikes in the solar wind are very narrow, are moving with the solar wind, and are relatively rare.


Basically, any variation would basically have to be periodic, and there's really no way to do it on short time scales.


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## Ghost (Aug 27, 2012)

shangrila said:


> The sun and moon would actually be two warring gods; whoever had the upper hand at the time would have their object (the sun or moon) dominate the sky.



Your concept sounds really cool! I think the society's adaptations have to make sense for this world. Other than that, I wouldn't worry too much about plausibility. Making your characters believable goes a long way in balancing out the fantastic elements.


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## Steerpike (Aug 27, 2012)

Have a bunch of pulsars around and something in the atmosphere that causes illumination when the pulsar is directed at the planet. Make the cycles variable.


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## Benjamin Clayborne (Aug 27, 2012)

Steerpike said:


> Have a bunch of pulsars around and something in the atmosphere that causes illumination when the pulsar is directed at the planet. Make the cycles variable.



Stop trying to make this plausible!  Besides, pulsars are periodic and have very short cycle times. The longest known pulsar cycle is less than 10 seconds.


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## Steerpike (Aug 27, 2012)

Benjamin Clayborne said:


> Stop trying to make this plausible!  Besides, pulsars are periodic and have very short cycle times. The longest known pulsar cycle is less than 10 seconds.



I thought there were some irregular ones for some reason.

Just have a bunch of them, going slower than real ones, and with some that are irregular. Maybe you could have interference between any given two is they are both pointed at the planet at the right time, so that sometimes waves from neither reach the planet.

Plausible? No


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## ThinkerX (Aug 28, 2012)

I once did the groundwork for a world which would have differing day/night intervals.

In my case, said world was a not quite tidally locked moon of a gas giant - so you'd get a long day/night cycle (a few days each) just from the moons orbit, which would be about a week, plus eclipses of varying length whenever the gas giant or another large moon came between the moon and the sun.  I went so far as to have a mythology of sorts worked out about this relationship.  After multiple migrane headaches I finally decided against it - though originally 'Falling Towers' was set on that world.


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## Astner (Aug 28, 2012)

Benjamin Clayborne said:


> Shifting planets into different orbits like that would most likely result in tidal forces that would destroy them.


Not necessarily, no. It depends on how you model it.



Benjamin Clayborne said:


> Any such system would still need to be fairly regular; you might see changes in day duration over the course of several years.


It doesn't have to stay in orbit for a full cycle, we're speaking of star system where stars are in orbits with each other. The orbits relative to a single star would never be elliptical.



Benjamin Clayborne said:


> A system where one day is four hours long and the next day is twenty hours long would be so chaotic that any planet in it would be quickly torn apart,


No it wouldn't, and if it would it would be scourged before it would.



Benjamin Clayborne said:


> or end up so close to a star that the surface temperature would be in the thousands of degrees.


Once again, not necessarily, it depends on how you model it.



Benjamin Clayborne said:


> Also there's the fact that rapidly and drastically changing the rotational speed of a planet will also tear it apart. The amount of energy involved in a planet's rotation is _huge_. Earth's rotational energy is 2.138Ã—10[sup]29[/sup] J. (By comparison, the energy of a 1000 kg car moving at 44 m/s (~100 MPH) is about 968,000 J. The planet has 220,867,768,595,000,000,000,000 times as much energy.) Any force that could change that substantially on anything less than a geologic timescale would rip the planet in half.


It wouldn't have to change the rotational speed, because what makes a day- and night-cycle is the rotational velocity _relative_ to the orbit, which it wouldn't stay in for long to begin with.



Jared said:


> To support Benjamin, Wikipedia puts the Moon's day-lengthening effect at 31 milliseconds per century.
> 
> Additional issues are that tidal forces fall off strongly with distance. If something were capable of doing this, it would be close (see: satellites, co-satellites, co-orbiters, or planet the object is a satellite of). And it would be relatively massive.
> Two issues with this one.


Do you know why that is? Because the moon has an inertia on earth's rotation. Which is irrelevant to the current system.



Jared said:


> First, dust densities are extremely low: optical depths for large structures _within the solar system_ are below ~10^(-5).


Correction, within _our_ solar system. We're not talking of a model anywhere close to our own.



Jared said:


> If you include molecules, then Enceladus' plume could occult ~10-15% of the light in a small region. But 10-15% in a small area is not night (by any definition). [The images of dense nebula and such appear opaque because they are huge-huge-huge, not because they dense.]


Once again, we're designing a new solar system not limiting us to _our_ solar system.



Jared said:


> Second, you would need a way to create a large-scale structure that is unstructured. In the solar system, Enceladus', Io's, and Pheobe's dust rings are structured. Dust columns created by Saturn's and Jupiter's magnetospheres are very narrow and structured (mostly, I think). Dust spikes in the solar wind are very narrow, are moving with the solar wind, and are relatively rare.


Well the cosmic dust would have to be in orbit as well, but that can easily be modeled in.



Jared said:


> Basically, any variation would basically have to be periodic, and there's really no way to do it on short time scales.


You're missing the point, the cosmic dust would be an addition to the star system. To occlude undesired light and make the effects seemingly more unpredictable.


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## Benjamin Clayborne (Aug 28, 2012)

Astner said:


> Not necessarily, no. It depends on how you model it.



You haven't actually presented a model where this might be plausible, so it's hard to comment on exactly what would be wrong with it. That said, I'm fairly confident there's no plausible physical model that would allow a planet to both have rapidly changing day-night cycles _and_ have the planet also be habitable by aerobic carbon-based life. But feel free to present a model that would allow this.


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## Astner (Aug 28, 2012)

Benjamin Clayborne said:


> You haven't actually presented a model where this might be plausible, so it's hard to comment on exactly what would be wrong with it.


We're not talking about a specific model but rather the plausibility of mathematically designing a model that fulfills the criteria set, to which there's no problem, as any trajectories in time are practically arbitrarily as shaped by gravitational focal points; moons, planets, and stars.



Benjamin Clayborne said:


> That said, I'm fairly confident there's no plausible physical model that would allow a planet to both have rapidly changing day-night cycles _and_ have the planet also be habitable by aerobic carbon-based life.


That's an appeal to incredulity, an informal fallacy.



Benjamin Clayborne said:


> But feel free to present a model that would allow this.


Once more, we're arguing the plausibility of such a model, and not how it would look.


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## Benjamin Clayborne (Aug 28, 2012)

Astner said:


> We're not talking about a specific model but rather the plausibility of mathematically designing a model that fulfills the criteria set, to which there's no problem, as any trajectories in time are practically arbitrarily as shaped by gravitational focal points; moons, planets, and stars.



I don't know what that means, mostly because you've got some phrasing problems in that sentence that make its meaning unclear. ("practically arbitrarily as shaped"... what?)

I'm under the impression that we're talking about a particular trajectory for a planet, near one or more stars or other large celestial bodies, that would cause the planet to have day-night cycles of _random, unpredictable duration._ I'm having trouble imagining how such a system could exist, so perhaps you could elaborate in detail instead of just asserting vaguely that it's possible. Multiple stars in super-close orbits? Planets swinging close by each other to throw one another into other orbits? Planets that sometimes are swinging close by a star at high velocity, and other times are far away? How would such planets maintain a habitable state without their atmosphere either burning away or freezing solid?



> Once more, we're arguing the plausibility of such a model, and not how it would look.



I'm _asking you_ how it would look, since as far as I know, the plausibility of such a model is basically zero. Can you actually elaborate on the details of such a system?


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## Astner (Aug 28, 2012)

Benjamin Clayborne said:


> I don't know what that means, mostly because you've got some phrasing problems in that sentence that make its meaning unclear. ("practically arbitrarily as shaped"... what?)


That's the point, I'm not trying to design a specific model but rather argue for the (theoretical) existence of such a model.



Benjamin Clayborne said:


> I'm under the impression that we're talking about a particular trajectory for a planet,


We're not.



Benjamin Clayborne said:


> near one or more stars or other large celestial bodies, that would cause the planet to have day-night cycles of _random, unpredictable duration._


We're talking about virtual randomness, something that appears random because the model is so complex and not all variables are accountable for. Now a closed trajectory would would necessitate systematic repetition, however if it repeats every million or so years then it's going to be difficult to map. An open trajectory would not necessitate systematic repetition, since the planet would never be in the same point twice.



Benjamin Clayborne said:


> Multiple stars in super-close orbits?


No, that would eventually scourge the planet.



Benjamin Clayborne said:


> Planets swinging close by each other to throw one another into other orbits? Planets that sometimes are swinging close by a star at high velocity, and other times are far away? How would such planets maintain a habitable state without their atmosphere either burning away or freezing solid?


Even in our own solar system the distance between planets are immense in contrast to their diameters. Not that other planets are necessarily needed in this design, but you could design their trajectories to never cross the earth's location in space-time.



Benjamin Clayborne said:


> I'm having trouble imagining how such a system could exist, so perhaps you could elaborate in detail instead of just asserting vaguely that it's possible.





Benjamin Clayborne said:


> I'm _asking you_ how it would look, since as far as I know, the plausibility of such a model is basically zero. Can you actually elaborate on the details of such a system?


I don't have the time to design such a model for this thread. But once again, we're arguing for the (theoretical) existence of such a design, and not how a specific design would look.


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## Benjamin Clayborne (Aug 28, 2012)

Astner said:


> I don't have the time to design such a model for this thread. But once again, we're arguing for the (theoretical) existence of such a design, and not how a specific design would look.



Okay, then. I don't think such a design is theoretically possible. I'm intrigued to see evidence to the contrary.


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## Jared (Aug 28, 2012)

Astner said:


> It doesn't have to stay in orbit for a full cycle, we're speaking of star system where stars are in orbits with each other. The orbits relative to a single star would never be elliptical.



The last time I read up on it, it wasn't believed that there were orbits where a planet could do figure-eight orbits around binary stars. The orbits that are stable are those where the planet is an elliptical orbit around one star and the other star is far out, or the two stars are close and the planet is much farther out and has an elliptical orbit around their barycenter.

In both of those situations, the days will not be randomly spaced. They will be periodic.




Astner said:


> It wouldn't have to change the rotational speed, because what makes a day- and night-cycle is the rotational velocity _relative_ to the orbit, which it wouldn't stay in for long to begin with.



You are technically correct, but the difference between considering the just the rotational period and the rotational and orbital periods together is pretty small until the (assuming prograde) rotational period approaches the orbital period.

And if you're doing this all through changing the orbit, what mass is going to be changing the orbit? The second star? Then you run into the issue of the figure-eight orbits.




Astner said:


> Correction, within _our_ solar system. We're not talking of a model anywhere close to our own.



Pet peeve: There is only one solar system, and that's the star system centered on Sol.

Serious comment: You haven't presented a model of a star system at all yet. You've been talking about broad generalizations and extrapolations made without real justification.




Astner said:


> Once again, we're designing a new solar system not limiting us to _our_ solar system.
> 
> Well the cosmic dust would have to be in orbit as well, but that can easily be modeled in.
> 
> You're missing the point, the cosmic dust would be an addition to the star system. To occlude undesired light and make the effects seemingly more unpredictable.



I'm not missing the point. I understand what you're saying. I'm just saying that I don't believe in its plausibility.

In space science, when we're considering a new planetary system, we look to what we already know exists and what we understand. When astrophysicists are looking at accretion discs, they look at mass loading and dust effects in the solar system (although I would say that they haven't been getting it quite right). This is how science works.

I'm just saying that, from my understanding of things, the star system would need to be in a nebula to get the kind of densities that you need; the star would need to to be moving quickly relative to the background dust to keep the star and planets from clearing the dust out; and the dust would have to be highly structured (going from zero density to really high density) on scale lengths of AU, compared to the light-year scale lengths of the nebula (ratio of 0.001%, extremely fine structure).

I seriously doubt the plausibility of that. And if it _were_ possible, then I have serious questions about the impact on the planet. That would be dumping a lot of dust on the upper atmosphere.



In the end, I'm still with Benjamin on this one: I'd be interested in seeing a model of how any of these can work but, until then, I doubt that it's possible.


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## Steerpike (Aug 28, 2012)

You could always make it artificial if that works for the story. Modified Dyson sphere built long ago by a mysterious race. Current inhabitants don't even have to know that is what they have. I don't know why it would be built for random cycles, but you don't necessarily need a natural explanation .


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## Astner (Aug 31, 2012)

Jared said:


> The last time I read up on it, it wasn't believed that there were orbits where a planet could do figure-eight orbits around binary stars.


I'd like to see the source for that, because I have a feeling that you're misinterpreting it.



Jared said:


> The orbits that are stable are those where the planet is an elliptical orbit around one star and the other star is far out


Prove it.



Jared said:


> You are technically correct, but the difference between considering the just the rotational period and the rotational and orbital periods together is pretty small until the (assuming prograde) rotational period approaches the orbital period.


First and foremost we work with two directions, the planetary rotation might be reverse to the orbital rotation. Secondly, the point was that we're dealing with the orbits as a variable.



Jared said:


> And if you're doing this all through changing the orbit, what mass is going to be changing the orbit? The second star? Then you run into the issue of the figure-eight orbits.


What issue?



Jared said:


> Pet peeve: There is only one solar system, and that's the star system centered on Sol.


Planetary system then, it's just semantics. In Sweden we use the same word for planetary system and solar system, my mistake.



Jared said:


> Serious comment: You haven't presented a model of a star system at all yet. You've been talking about broad generalizations and extrapolations made without real justification.


The question we're discussing is: _Could such a model exist?_; Not: _How would such a model look?_

Just like you don't have to know detailed behavior of a certain function to prove certain attributes of it.



Jared said:


> I'm not missing the point. I understand what you're saying. I'm just saying that I don't believe in its plausibility.


Well, your belief is not a factor in this debate.



Jared said:


> In space science, when we're considering a new planetary system, we look to what we already know exists and what we understand. When astrophysicists are looking at accretion discs, they look at mass loading and dust effects in the solar system (although I would say that they haven't been getting it quite right). This is how science works.


No, observation is only part of science. We've never made any direct observations of a black hole for one, it's primarily a theoretical construction.



Jared said:


> I'm just saying that, from my understanding of things, the star system would need to be in a nebula to get the kind of densities that you need;


Why?



Jared said:


> the star would need to to be moving quickly relative to the background dust to keep the star and planets from clearing the dust out; and the dust would have to be highly structured (going from zero density to really high density) on scale lengths of AU, compared to the light-year scale lengths of the nebula (ratio of 0.001%, extremely fine structure).


Instead of picking numbers of off Wikipedia, get to the point. What's the problem?



Jared said:


> I seriously doubt the plausibility of that. And if it _were_ possible, then I have serious questions about the impact on the planet. That would be dumping a lot of dust on the upper atmosphere.


Once again, your belief has nothing to do with the debate. You either provide evidence, or you don't.



Jared said:


> In the end, I'm still with Benjamin on this one: I'd be interested in seeing a model of how any of these can work but, until then, I doubt that it's possible.


I'm sorry, but that's not how debating works. One piece of evidence is worth more than a billion opposing opinions.


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## Benjamin Clayborne (Sep 4, 2012)

> The question we're discussing is: _Could such a model exist?_; Not: _How would such a model look?_



I'm going to say, once again, no. Such a model cannot exist.



> Once again, your belief has nothing to do with the debate. You either provide evidence, or you don't.
> 
> I'm sorry, but that's not how debating works. One piece of evidence is worth more than a billion opposing opinions.



It's strange how you demand evidence for our position, when you in fact haven't provided a single shred of evidence that such a model could exist.


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## ThinkerX (Sep 4, 2012)

Like I said earlier a 'world' that is actually a close orbiting, slowly rotating moon of a gas giant should produce most of the effects the OP is after and still be credible from a science POV.

(But after repeated migrane headaches trying to puzzle things through, I gave up on the concept.)


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## Benjamin Clayborne (Sep 4, 2012)

ThinkerX said:


> Like I said earlier a 'world' that is actually a close orbiting, slowly rotating moon of a gas giant should produce most of the effects the OP is after and still be credible from a science POV.
> 
> (But after repeated migrane headaches trying to puzzle things through, I gave up on the concept.)



Close-orbiting a gas giant would be pretty obvious: most of the time there's a huge planet blocking half the sky... but it's also going to be a very regular, predictable process.


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## ThinkerX (Sep 4, 2012)

> Close-orbiting a gas giant would be pretty obvious: most of the time there's a huge planet blocking half the sky... but it's also going to be a very regular, predictable process.



If you also assume that the moon is rotating on its axis with a period equal to say...half or a third of its orbital period of the gas giant...you get a day/night cycle so complex it might give the (false) appearance of being random.  The trick would be to have the moon orbiting just far enough out so its not tidally locked.

Depending on just what the rotational period of the moon is, and the duration of the orbit about the gas giant, you could end up with periods of protracted darkness...or daylight...or a series of fairly short day/night intervals.  

But then again, I gave myself some serious headaches trying to puzzle this one out.


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## Carl (Sep 4, 2012)

shangrila said:


> Thanks for the replies.
> 
> I wasn't thinking of a scientific reason. My first idea was of a realm, something that wasn't a typical planet and actually had a completely random rising of the sun and moon. The sun and moon would actually be two warring gods; whoever had the upper hand at the time would have their object (the sun or moon) dominate the sky.



This answers the original question you had. The two warring gods makes your idea completely feasable without having to go into complex scientific equations to model the planets path through a complex solar system. Keep it simple so that you don't lose your audience just describing the night sky.

I think your idea would make for an interesting world where anything would be possible.


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## Jared (Sep 4, 2012)

Astner, I understand that on the internet, there are no faces or intonation. All you have is text. It is very easy to read tone into just words that are not meant.

But.

I find no way to read what you wrote to me in any light that does not go from abrasive to insulting to offensive.





Astner said:


> Well, your belief is not a factor in this debate.
> 
> Instead of picking numbers of off Wikipedia, get to the point. What's the problem?
> 
> Once again, your belief has nothing to do with the debate. You either provide evidence, or you don't.



When I say things like "the way I understand it" or "I don't believe that that's true" or "I think that there might be another explanation for that," I am not hedging because I am uncertain. I phrase things like that because it's more polite than the blunt "this is wrong."

It is also the way that people in my field speak. I sometimes forget that not everyone speaks that way and it can cause confusion.


I picked up these speaking habits in the same place that I picked up the numbers I tossed out and the lingo that I used. It wasn't on Wikipedia, it was in graduate school when I was earning my doctorate in Space Physics.

Space Physics is the field that deals with things like dust in a planetary system. We strongly overlap with planetary scientists, who investigate topics like planetary formation, stable orbits, and orbital variations. (My Bachelor's in Geology makes this a bit easier since I already am familiar with Earth's formation and evolution.) This discussion thread lies fully within the realm of science that I've spent more than a decade studying.

I was trying to be polite and to not assert myself as a definitive authority because of my degrees (because I'm not, even though I know much more than the vast majority of people). But when you essentially call me disingenuous, ignorant, and a liar, I will set aside that inclination.


Astner, I strongly suggest that you walk away and calm yourself.


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## Astner (Sep 4, 2012)

Jared said:


> Astner, I understand that on the internet, there are no faces or intonation. All you have is text. It is very easy to read tone into just words that are not meant.
> 
> But.
> 
> I find no way to read what you wrote to me in any light that does not go from abrasive to insulting to offensive.


I'm not being offensive, I'm being direct. Belief is a non-factor in debate. You present- and explain your evidence and leave it at that.

Furthermore you're presenting numbers with five- or six significant figures which is of absolutely no relevance to the topic — numbers you more than likely attained from sites such as Wikipedia despite your educational background. Which further speaks of your unwillingness to concede on a topic you clearly did not initially grasp as you time after time again requested a specific model as verification for the existence of such a model.



Jared said:


> When I say things like "the way I understand it" or "I don't believe that that's true" or "I think that there might be another explanation for that," I am not hedging because I am uncertain. I phrase things like that because it's more polite than the blunt "this is wrong."
> 
> It is also the way that people in my field speak. I sometimes forget that not everyone speaks that way and it can cause confusion.


Don't. If you find something wrong then you explain why you think it's wrong. You don't focus on the semantics worrying about offending me and then _neglect_ to mention your reasoning for why it's wrong.



Jared said:


> I picked up these speaking habits in the same place that I picked up the numbers I tossed out and the lingo that I used. It wasn't on Wikipedia, it was in graduate school when I was earning my doctorate in Space Physics.


That's funny because I recall when earning my Master's in Fundamental Physics people tended to be very direct. If you misused a Lie group while deducing symmetric relations in Yukawa couplings you'd have the error pointed out — and explained — the moment it was noted by a classmate or a professor, and no one would get offended by this.

I can't confirm or disconfirm your claims to an educational background and while I have my suspicions those are neither here or there.



Jared said:


> Astner, I strongly suggest that you walk away and calm yourself.


And I'll suggest that you stay on topic, as for now you've only managed to derail the thread ignoring every argument of my reply. You'll either address the reply properly or I'll take it as a concession.

Besides, I'm not the one who just spent half a page complaining about how offended I got when someone constructively criticized me for using fallacious arguments and irrelevant numbers. You are.


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## Benjamin Clayborne (Sep 4, 2012)

Astner said:


> Besides, I'm not the one who just spent half a page complaining about how offended I got when someone constructively criticized me for using fallacious arguments and irrelevant numbers. You are.



**puts on moderator hat** This is getting personal and extremely off-topic. Any discussion about personal attitude is going to stop right now.

**takes off moderator hat** I'm still waiting for evidence supporting the assertion that a model can exist that allows for random day-night lengths.


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## Steerpike (Sep 4, 2012)

Benjamin Clayborne said:


> **takes off moderator hat** I'm still waiting for evidence supporting the assertion that a model can exist that allows for random day-night lengths.



All you need in your model is a deity who actively intervenes in the universe and implements the random cycle. So take any model of a solar system you like, draw a box somewhere, write the word "deity" in it, and you're done


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## Jared (Sep 4, 2012)

Astner said:


> And I'll suggest that you stay on topic, as for now you've only managed to derail the thread ignoring every argument of my reply. You'll either address the reply properly or I'll take it as a concession.



All right. Let's start over.

You've stated that something is scientifically plausible. The burden of proof is thus on you. I then respond to your evidence.

To that end, I would greatly appreciate if you could collect and reiterate what arguments exactly I am supposed to respond to.

We are discussing a perfectly random day/night cycle where any day or night can last between (real world Earth) hours and days. You have suggested either complex orbits among multiple stars or cosmic dust. Here are my questions.


*Dust*
_Are the grains orbiting the star?_ Why weren't they swept up in planetary accretion? Why haven't they collapsed in to the star from Poynting-Robertson drag or been pushed out from radiation pressure effects? Both of these effects work on short (compared to planetary lifetimes) time scales.

Any grains would be ionized, and thus vulnerable to pick-up by the stellar breeze/wind. In the solar system, ionization rates at Mars for molecules are something like 10^-6 /s. Given photoionization and stellar wind-driven ionization, ionization of the dust should be (much much) larger than 0.01% of that, but let's use that lower bound. In that case, the lifetime against ionization would be ~300 years. When a dust grain is ionized, it is removed by the stellar wind. So within ~3000 years, assuming a mature star and no other effects, all of the dust would be removed.

Are the grains restricted in star-centered distance? If not, why has keplerian shear not removed any coherent (integrated along the star-planet line) azimuthal structure? If so, how are they kept at one distance given that even small width lead to shearing on the scale of years (as seen by the dust)?

_Is the dust coming off of objects orbiting inside of the planet?_ If so, how could they create a night over any appreciable region of the planet's surface?

_How much dust would you need?_ I would start at a zeroth-order approximation where the minimum amount of dust is the number of micron-sized grains to fill a disk the size of the planet. If we take a planet with a radius of 6000 km (slightly smaller than  Earth), then we'd require a little over 3x10^25 grains for any given occultation.

If we assume that the amounts of day and of night are equal and that the planet orbits at 1 AU, then we'd need [0.5 * 2 * pi * (1 Astronomical Unit) * (3x10^25 grains) * ((10^(-6) m)^3/grain) * (1000 kg/m^3)/ (12000 km) ~=] 10^15 kg of material at any given time (averaged over the lifetime of the random day/night). [The 1000 kg/m^3 is the density of water. A lowball for material and porosity.]

Remembering my estimation that all of the dust will be removed in 3000 years, if the star system is 3 billion years (for roundness) old, then ~10^21 kg of material must have been produced. That's over one percent the mass of Earth's Moon. This is an extremely rough estimate. It's assuming the dust is at the planet's orbit, it's lowballing the removal rate, it's estimating the density, it's a gross estimate of the size of the occulting particles. I would need to sit down and try this calculation for different configurations, but I think that the case only gets worse.

What is destroying any such massive objects near the sun and deploying the dust in such a broad pattern? If the random day/night started recently, what would have been it either occur smoothly over time or completely all at once (and spread out the dust in such a way that previously discussed issues are avoided)?



Notes.1: I have to head out, so I'll stop here for now. I have more questions about the effects of being within a super-star-system dust cloud. And about the planet flipping between stars.

You (Astner) asked before for me to prove that figure-eight orbits around binaries are unstable. Here's a quick link to NASA Goddard's website and a Bad Astronomy comment. If you have access to scientific journals, I can link doi's next time.

Useful things to consider for the two stars are Hill spheres, periodicities, slingshot effects, and linear combinations.



Notes.2: I did a quick check of my arithmetic, but I'm not infallible. If I made an error, please just point it out with what the correct value is.


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## Carl (Sep 4, 2012)

Like I mentioned before and Steerpike mentioned in fantasy writing once the God or gods card is dropped your model is done. If this was a strictly Sci-fi book you would need some form of explanation for the randomness of it. As this original question stands I believe it has b
een answered.


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## shangrila (Sep 5, 2012)

Yeah, honestly, I was never really looking for a scientific reason for it. I appreciate all the work the posters have put in to this thread and it's spawned more than a few ideas, but still, the original point was whether or not this idea was stupid. I'd seen random weather patterns and the like in conworlds before, but never something as radical as what I've suggested here and I was worried that it would come off as contrived, stupid or lame.

It's good to know it's not any of those, judging from the positive comments. So...thread objective achieved. Cheers


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## Astner (Sep 5, 2012)

Benjamin Clayborne said:


> **takes off moderator hat** I'm still waiting for evidence supporting the assertion that a model can exist that allows for random day-night lengths.


I've addressed that earlier.



Jared said:


> All right. Let's start over.
> 
> You've stated that something is scientifically plausible. The burden of proof is thus on you. I then respond to your evidence.


The evidence is that you're able to model the trajectory of the planet arbitrarily due to it being an overdetermined system. It's called the generalized- or weighted n-body problem.



Jared said:


> We are discussing a perfectly random day/night cycle where any day or night can last between (real world Earth) hours and days.


Define random.



Jared said:


> a*Dust*
> _Are the grains orbiting the star?_


Not necessarily, but your arguments are rather easy to address.



Jared said:


> Why weren't they swept up in planetary accretion?


Because the dust doesn't get close enough to the planets.



Jared said:


> Why haven't they collapsed in to the star from Poynting-Robertson drag or been pushed out from radiation pressure effects?


Free-body diagram balance between the two, assuming that the dust doesn't leave the planetary system.



Jared said:


> Any grains would be ionized, and thus vulnerable to pick-up by the stellar breeze/wind. In the solar system, ionization rates at Mars for molecules are something like 10^-6 /s. Given photoionization and stellar wind-driven ionization, ionization of the dust should be (much much) larger than 0.01% of that


Why?



Jared said:


> Are the grains restricted in star-centered distance?


Not necessarily, no.



Jared said:


> If not, why has keplerian shear not removed any coherent (integrated along the star-planet line) azimuthal structure? If so, how are they kept at one distance given that even small width lead to shearing on the scale of years (as seen by the dust)?


Why would the dust have to be in a stable trajectory around one star? The sole purpose of the dust is to bloat out star-light, not to remain in orbit around a single star for years or decades. In fact the planet in question will leave the 



Jared said:


> _Is the dust coming off of objects orbiting inside of the planet?_ If so, how could they create a night over any appreciable region of the planet's surface?


No.



Jared said:


> _How much dust would you need?_ I would start at a zeroth-order approximation where the minimum amount of dust is the number of micron-sized grains to fill a disk the size of the planet. If we take a planet with a radius of 6000 km (slightly smaller than  Earth), then we'd require a little over 3x10^25 grains for any given occultation.
> 
> If we assume that the amounts of day and of night are equal and that the planet orbits at 1 AU, then we'd need [0.5 * 2 * pi * (1 Astronomical Unit) * (3x10^25 grains) * ((10^(-6) m)^3/grain) * (1000 kg/m^3)/ (12000 km) ~=] 10^15 kg of material at any given time (averaged over the lifetime of the random day/night). [The 1000 kg/m^3 is the density of water. A lowball for material and porosity.]
> 
> Remembering my estimation that all of the dust will be removed in 3000 years, if the star system is 3 billion years (for roundness) old, then ~10^21 kg of material must have been produced. That's over one percent the mass of Earth's Moon. This is an extremely rough estimate. It's assuming the dust is at the planet's orbit, it's lowballing the removal rate, it's estimating the density, it's a gross estimate of the size of the occulting particles. I would need to sit down and try this calculation for different configurations, but I think that the case only gets worse.


Three millennia is more longer than the earth would stay in orbit around one star. Furthermore the trajectory of the dust can be modeled too and may well have entered the solar system past with or after the planet in question did.



Jared said:


> Notes.1: I have to head out, so I'll stop here for now. I have more questions about the effects of being within a super-star-system dust cloud. And about the planet flipping between stars.


I hope they are more relevant than your previous ones that build upon a specified 



Jared said:


> You (Astner) asked before for me to prove that figure-eight orbits around binaries are unstable. Here's a quick link to NASA Goddard's website and a Bad Astronomy comment. If you have access to scientific journals, I can link doi's next time.


Look up Kepler-16b.

Other than that, yes, I'd like to see these journals.

Though I wouldn't argue that stability is a necessity like you're implying though, in fact I'd argue against it since a stable orbit would have a periodic behavior thus not emulating the random element desired.


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## Ghost (Sep 6, 2012)

shangrila said:


> My first idea was of a realm, something that wasn't a typical planet and actually had a completely random rising of the sun and moon. The sun and moon would actually be two warring gods; whoever had the upper hand at the time would have their object (the sun or moon) dominate the sky.



I think your idea is great. If you love the idea, it's worth pursuing. I don't see how plausibility matters. Things only have to be plausible within the story. When you set scenes and show how life on this world shapes your characters, it becomes believable. The way you weave it into the narrative determines whether the reader will accept it or not. A plausible idea can sound stupid or an outrageous one can make sense. It depends on how you tell the story.



shangrila said:


> Yeah, honestly, I was never really looking for a scientific reason for it.



LOL


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## Griffin (Sep 6, 2012)

shangrila said:


> This is an idea I had recently, so I thought I'd put it up here and see what people think and, ultimately, if it's worth pursuing.
> 
> Basically, it's as the title says; days and nights are random in length. They could last for a few earth days, a week, or only a few hours (that would be the minimum). A group of people do their best to predict it but it's more of an educated guess than an actual prediction, like weather forecasting in real life.
> 
> So my question would be; is this idea somewhat plausible to you? Or is it just too stupid to bother with?



Ignoring the feud, it sounds like your idea is more mythologically based. Trying to explain it scientifically might put off readers who failed physics like myself. I do like the idea. Maybe not so random, but very similar to Alaska. "Day" can last a few hours to all day depending on the time of year. 

I'd say go for it. Whether or not it's "plausible" is a different (and unnecessary) story. The idea can be plausible and does not sound stupid at all.


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