World set in a Binary Star System - Should I drop the idea?

[mithril]

Hi folks.

I had this vision of a world orbiting one of the stars in a binary star system for a fantasy project. In order to make it real I've searched a number of topics relating to astronomy. However I seem to have hit a snag fairly early into the project.

This has to do with how the skies would look on such a world with more details here.

Now my problem is that I've been unable to make any further progress on this on my own. The world building has thus come to a near standstill. I've sketched in the basics of the magic system of this world and have done some work on the religious beliefs. (I'll be asking your advice on those later )

However I'm wondering if for the rest, I should give up this particular astronomical setting and go with a simpler Sun-Earth-Moon setting, keeping this one for any future projects I might do.

The other option is to continue with sketching in those aspects of the world which have relatively less bearing on how bright the night is and the number of suns during the day. Then if I do get some insights later on, I could do the remaining parts.

I am more inclined towards the first as I find that too many aspects of the society would at least peripherally depend on the kind of skies the world has been exposed to.

Does putting off the 'world with 2 suns' (i've still not settled on a name ) for some future project make sense even though this world was the inspiration for trying to write at all?

 

[HareBrain]

Does putting off the 'world with 2 suns' (i've still not settled on a name ) for some future project make sense even though this world was the inspiration for trying to write at all?

I'm a physics no-know, but I do know you shouldn't be afraid to dump the initial inspiration for a story if it no longer works. Many stories outgrow and leave their parent ideas.

 

[Blackrook]

My father, who has two Phd's, helped me design a world that orbited around a gas giant. It takes scientific knowledge that is probably beyond most writers. But if you need help, contact the astronomy department of a local university. You might find a student or professor willing to help you.

 

[Sapheron]

I can help you to a degree, I've studied planetary geology and physics a reasonable amount, and read about it outside of work also. Chris might pop in and give some advice too, he's usually into this sort of thing from what I remember.

Having looked briefly at your link, as I'm too tired to go in depth this evening (maybe at the weekend) I was struck by one thought initially. Is it really necessary to go into great detail working things out? This is fiction. As long as things are roughly ok (or have an explanation for not being so) then a good story carries past minor impossibilities or inaccuracies.

Anywho, over the weekend, if not tomorrow, I shall answer your questions in as much depth as I can.

 

[Vertigo]

I can't remember which one of them it was but one or two of Peter Hamilton's Nights Dawn books had a world in a binary system with some interesting crop cycles that come of it. Might be worth a look both for ideas and how much depth you might need to make it believable, as he did a pretty good job of it.

 

[Nik]

If you set the binary partners sufficiently apart, you can minimise the second's influence. Think of it as a daylight star or super-full-moon but as a point source.

If there's less than ~20 AU separation, you have complexities. You certainly do not have 'outer planets' as they will not have stable orbits. You may need to set your 'world' as a giant moon of a gas-giant to provide enough moons to give a solar-system to explore easily...

 

[Cayal]

The great thing about fantasy is it doesn't have to be real.

 

[DrMclony]

It's worth remembering that a lot of our theories on planetary physics are not based on observation of reality. Provided you pay attention to what is thoroughly proven, you can make any setting work within reason. Because there is still the larger majority of it that we simply don't know!

You can employ various literary tools to explain, or get away with not explaining. If your scientists don't know something, then why should the reader? make it clear there are mysteries there!

In my third book Dance of Nevermind, I have a gas giant that sweeps close in an erratic orbit to the planet causing all sorts of mayhem. But the actual knowledge we have about that particular situation is still limited and largely based on (educated) guesswork. After a lot of research to ensure the science is right, I have come to the conclusion that the science simply doesn't have all the answers for my particular setup. It may be that in your case its the same. Follow the sciecne that exists, and build your mysteries around it. Then you should be able to get away with a lot of stuff provided its written well.

And if it is a fantasy universe, then you have even more scope as you dont have OUR universal physical laws to contend with.

 

[mithril]

Thanks everyone for your inputs.

Vertigo - I'll check out Peter Hamilton's Nights Dawn books if I can.

Sapheron - A big thank you for saying you'll look it over over the weekend! I'm excited now! As for whether the world needs to be so detailed, I also believe that so long as details are roughly ok it should be fine. Which is why I've simplified most of the data given in that link. The position of the second star at various times of the year might not be important enough. However I feel the brightness at night would definitely be imp.

It would definitely give rise to a whole lot of mythology. Even on Earth there are stories relating to the Sun, the Moon and why eclipses occur. Now imagine if we had a super bright star which gave light as good as streetlights (for ex) for over half a year!

A list of things that I can think of offhand that would be affected would be
1. Religion/mythology - Maybe the Sun and the Moon are brothers and the bright star their mother who lives with each of them alternatively for half a year... quite possible for it to crop up somewhere. Lots of variations over regions possible..

2. Work cycles - since the night won't ever be bright enough to feel like day, it shouldn't affect the circadian rhythms but societies might evolve to take advantage of the bright nights to get more work done... As far as I've understood, in an absence of a widespread and easily available source of light at night, societies tend to sleep early and tend to become highly attuned to the sun. If the nights were also bright enough to work by, the work day might be longer for that time. And if so it'd have to be an important and integral part of society, and consequently something the novel can't ignore.

3. Flora-fauna - Like the many night blooming plants we have there should be corresponding plants that only bloom in bright nights. Dark nights (with just the moon) might be too dark for them and the sunlight too bright...

4. Magical effects relating to the secondary star

Any number of ideas/variations can be introduced as and when required/needed. But for that I need to know the min and max brightness of the secondary star at night at the very least

Cayal - Though it is a fantasy, I still don't want any intelligent reader coming from a science background to go "That's ridiculous! She hasn't bothered to put in any efforts at all. "

Nik - I'm not that concerned with having enough moons/planets to make solar system easy since this will be a fantasy world with limited technology levels. Not precisely low tech but space exploration is definitely not a concern.

Thanks for the giant moon around a gas giant idea. That was actually the second scenario I had in mind. However since I've not really done any research on that one. I had put it lowest on my possible worlds list .

Blackrook - You are seriously lucky to have your father helping you design worlds. How cool is that! I'm sort of jealous

Harebrain - Thank you for saying that. I had started feeling a bit guilty about thinking of ditching my baby You are right. If it doesn't work, it should go.

Thank you all...

 

[mithril]

It's worth remembering that a lot of our theories on planetary physics are not based on observation of reality. Provided you pay attention to what is thoroughly proven, you can make any setting work within reason. Because there is still the larger majority of it that we simply don't know!

You can employ various literary tools to explain, or get away with not explaining. If your scientists don't know something, then why should the reader? make it clear there are mysteries there!

Follow the science that exists, and build your mysteries around it. Then you should be able to get away with a lot of stuff provided its written well.

And if it is a fantasy universe, then you have even more scope as you don't have OUR universal physical laws to contend with.

Thanks for the very practical advice DrMclony. I intend to not actually tell the reader every single detail i've worked out. The reader would be told only what the POV character might know. And your suggestion to have unsolved mysteries makes a lot of sense to me.

Doesn't not having OUR universal physical laws mean I've to know how those laws differ in the two universes? Though now that you point it out, since common people might not even know about their sun having a twin... They might just see it as a freak star... In which case having the explanation for its behaviour is nice but it is not needed to explain it... (if that makes any sense )

Thanks for the thoughts

 

[Vertigo]

Note that you would not have light at night all year round. At some points in your planet's cycle of it's sun it would be in a position where both suns are in roughly the same direction and at these times your planet's night time face would be away from both of them so you would have a normal dark night. How long this would be the case for would depend entirely on the relative orbit times. But on the almost certain assumption that the orbit time of your planet around it's sun is considerably less than the two sun's orbit times around the barycenter (the centre of mass of the whole system) then you are likely to have dark nights for half of the year and light ones for the other half.

Note that in a binary system the two suns would both orbit around a point that is the centre of mass of the two combined bodies (their barycentre), whilst your planet would be orbiting about it's one sun. To see animations of the orbits of various combinations of different or similar sized binary stars take a look at this link and go down about 3/4 of the page.

http://en.wikipedia.org/wiki/Barycentre#Barycenter_in_astronomy

You then have to imagine your planet orbiting one of the suns in the animations and that orbit would almmost certainly be many orders of magnitude faster than the two suns' orbiting. I don't know, but I suspect the period of orbit of binary suns about their barycentre will typically be in the order of centuries, unless they are very close to each other in which case they would almost certainly be too close for any chance of planets having stable orbits. Again, unless they actually orbited outside the orbit of both suns ie. the two suns are extremely close together - not sure if that would be stable or not.

 

[mithril]

Though in my more detailed post about the issues here, I've listed the point up to which I was able to finalise things somewhat.. I forgot to include these points . So a big thanks to Vertigo for pointing out those omissions.

I'll go and make an addition to that thread with the following additional info.

The secondary star would be visible during the day for half a year and during the night time for the other half.

During the times it is visible during the day, it would be outshone by the primary so that there is no real difference to the day's brightness. However it would still be visible except at times when it's position is too close to the sun in the sky.

While the secondary star is visible during the night, it would be seen as the brightest object in the sky (including the full moon), and would be the primary light source for the night during this time of the year. These nights will be termed as 'bright nights', with the night with just the moon as normal nights. The moon of course changes phases normally.

 

[FeedMeTV]

In order for a planet to orbit one star in a binary system, rather than orbiting around both (and the centre of mass) presumably it would have to be quite close so as not to be overly affected by the mass of the second star - would it be able to maintain enough distance to support life? I'm not a scientist so I am probably completely off the mark but it just made me wonder.

I hope it would work though because I'd be interested to hear how your characters dealt with their bright nights, particularly the myths and legends surrounding it that you mentioned Mithril.

 

[Anne Martin]

You might take a look at Brian Aldis' Hellenconia Trilogy to see how he does it. IIRC, the two suns are of quite different magnitudes and the seasons last 400 years, due to the juxtapositions between the suns. It's been a long time since I've read them, though.

 

[MstrTal]

I read one series, long time ago, that used a binary system. Their planet orbited around the primary sun of the two and for the most part the second star ranged little more from a distant orb of light to a growing harbinger of ill fortune. As memory served me when the second sun was at its closest point it caused all sorts of havoc on the planet. Drought, extreme heat, massive shifts in weather and the natives end up going underground.

 

[chrispenycate]

I wrote in my hospital bed a long exposé on the situation, but since I didn't have a computer, it's all longhand, in notebook, and I'm having trouble concentrating on anything now enough to get it typed up.

But note that the "nights of light" would slowly precess round the calendar, from winter through the cycle of seasons until it got back to where it started.

V, I think we can consider the solar system, the existence of Jupiter doesn't prevent the interior planets from having stable orbits, despite its mass and the fact that its period is only in decade, nowhere near centuries. Oh there will be a bit of wobble, but not enough to be life threatening
If you consider a really big gas giant planet at 15 AU mean orbit (for the forty years), halfway between the orbits of Saturn and Uranus, half as far out again as Jupiter so its increased mass will have even less of an effect on the innersystem,give it a system of moons, the result should be reasonably stable, no? Now, if we set fire to it (it's a gas giant, so there's lots of potential fusion fuel) nothing has changed gravitationally, and we now call its moons planets…

 

[FeedMeTV]

Ah! Beautifully explained, chrispenycate, you have made it all much clearer in my head!

 

[Cayal]

Cayal - Though it is a fantasy, I still don't want any intelligent reader coming from a science background to go "That's ridiculous! She hasn't bothered to put in any efforts at all.

If your book is published, what percentage do you think will have the knowledge to know if you are close to being right.

I mean, look at Star Wars, lightsabers are impossible, but Starfighters do not shoot coloured lasers. It sure hasn't driven any real criticism of the movie/books.

 

[Lilmizflashythang]

I have a binary system of a sort. If I remember correctly, there is a binary system where one star revolves around the other and not some central mass.

 

[Sapheron]

I've answered about the astronomy side of things with a few asides I felt like putting in. I'll have a think more about the effects on plants, animals, people and perhaps add to it.

Hope it helps you.