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Looking for help with a Ring World Model

  1. Jun 23, 2014 #1
    Hello everyone.

    I am world-building for a fantasy setting. I've had an idea and I'm not sure if it's feasible or not.

    I'm trying to model a non-standard world type and I wanted to see if I'm on the right track.

    The idea is for a ring world. The outside is habitable. I've already got a magic hand-wave-type explanation for why everyone sticks to the ground and the ring doesn't fall apart under it's own weight. Diameter and weight of the ring shouldn't be limitations.

    The ring itself will rotate very slowly, at a rate of one revolution per year. That's how the annual cycle is measured for this setting.

    Above the ring, I want to have an even number of 'suns'. At least four. They float in orbit above the ring, and move faster. The orbit isn't gravity-based, so we don't have to worry about orbital velocities or anything like that.

    They orbit the ring in the same direction that the ring rotates, but faster. The idea is I want the day/night cycle of a given point on the ring to be determined by whether or not they have line of sight on one of the suns. Day and night should be the same length, so any point on the ring should have line of sight and lack line of sight for the same amount of time each day.

    I'm trying to get a sense of how big my ring world needs to be in order for the suns to still be high enough up that they are unreachable for all practical purposes.

    My idea for a four sun system is to think of it like this:

    1. Draw a circle.
    2. Draw an octagon around that circle such that each side of the octagon touches the circle.
    3. Label every second vertex of the octagon as 'sun'. The unlabeled vertices have no sun.

    To my way of thinking, this would give me a rough idea of the ratio between the radius of the ring and the height of each sun. I should then be able to plug in the desired height for the suns and reverse-calculate my way to get what the radius of the ring needs to be to feasibly have that number of suns around it.

    I could do similar calculations for other numbers of 'suns' - using a 12-sided regular polygon for a world with six suns, or an 16-sided regular polygon for a world with eight suns, and so forth.

    What I want to know is: Does this kind of modelling make sense to get the values right, or have I got a critically false assumption buried in there that would make it all fall over?

    Also, any additional thoughts or criticisms or highlighting of possible problems would be welcome. :)

    Thanks for reading.
  2. jcsd
  3. Jun 24, 2014 #2


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    It works (and you can calculate the numbers in the same way), but why do you need so many suns? A single sun, far away, rotating around once per day, does the same job, and you don't care about orbital mechanics, astrophysics or other laws of physics anyway. Or let the ring rotate once per day, that's easier I guess.
  4. Jul 3, 2014 #3
    Story reasons. :P

    I have an idea that one of the 'suns' was historically destroyed. Which means that there is one 'day' during the week with no light. I want to give that day per week significance in the history of the world and the storyline I have in mind.

    Just an idea I've been kicking around. May or may not go with it... Just wanted to check that I wasn't off base in my back-of-the-envelope level modelling.

    Thanks. ^_^
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