1. JennaPeterson88

    JennaPeterson88 Member

    Nov 7, 2011
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    Newfoundland, Canada

    Creating a Planet

    Discussion in 'Setting Development' started by JennaPeterson88, Apr 12, 2016.

    Alright, so, I need to create a planet to set my sci-fi on. I don't need to nail down all the scientific data, but I need to have a basic understanding of my planet. I want it to be similar to Earth in a lot of way, with a few major differences.

    Similarities with Earth:
    - Similar size. Every so slightly smaller, to allow for slightly ever so slightly less gravity.
    - Similar distance from its host star, such that it would experience the same temperatures if it had the same tilt and rotation.
    - Orbits a red dwarf star pretty much exactly like ours.

    Differences with Earth:
    - Not tilted at all
    - Rotation is slower. A day on this planet lasts approximately 1.8 Earth days (about 43 hours).
    - Orbit around the sun is faster, and slightly closer, resulting in a year that is 317 Earth days (about 203 of its own days)
    - Has 3 moons, all of which do not rotate. All are similar to ours in size. 2 are on opposing tilted orbits at the same distance from the planet, such that their paths across the sky creates a cross with 60/120 angles instead of 90/90 angles. The third moon is further out.
    - Only has one small continent surrounded by a scattering of tiny islands that are mostly uninhabited. The continent is almost 2 separate land masses, but they're joined by a thin land bridge. The larger segment has about the same area as today's Algeria, while the smaller one would have the same area as Spain & France put together. That's it. This continent is positioned so that it crosses over the equator, but lies 70% in the northern hemisphere. The rest of the planet is ocean with polar icecaps. The continent is covered in temperate-to-tropical rainforest.

    What would the weather be like? I've read that if Earth slowed by half (48 hour day), we'd have major storms, because of the greater temperature difference between day and night sides. I don't want to create an extremely stormy place, but frequent, moderate winds are good. Perhaps this effect would be less near the equator, given that area heats the most and would thus loose the least heat at night? The dominant species are tree dwellers who evolved from something similar to a sugar glider, and they retained the gliding ability. They're also primarily nocturnal, though the beginning and end of their waking "day" will be the "evening" and "morning" in terms of sunlight, as they won't be sleeping 15+ hours at a time. I'm thinking 9-10 hours would be a normal sleeping time. They sleep during the hottest & brightest part of the day, and are able to see well in the moonlight, but their eyes are adapted to shield against the powerful sunlight for the "daylight" part of their normal waking days / in the event they need to be awake when they would normally be sleeping.

    Is it reasonable that a tree dwelling species would have stayed smaller (adults standing in the most erect posture they're capable of holding would be around 4'6 or so, with variance for individual genetics and sex differences), or should the fact that this planet has a little less gravity than Earth make them bigger?

    Is there anything I can nail down in regards to the planet's physical make up, or its electric field, etc. that would allow for light storms in the night sky similar to Earth's aurora borealis? I need something like this to happen over the landmass where the inhabitants would see it (close to the equator), as it is a vital part of their belief system.
  2. Lalochezia

    Lalochezia New Member

    Aug 26, 2015
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    Bay Area, CA
    I believe you are correct about the weather.

    One thing to consider is the planet's mass: gravity is what holds the atmosphere to a planet, and less mass is going to mean a thinner atmosphere, which would also definitely affect the weather (potentially making it milder, which is good for you). Though if the planet doesn't have enough gravity to hold oxygen in its atmosphere, everything on your planet is going to die.

    Auroras tend to happen at the magnetic poles of a planet, and it is entirely possible for these to not line up with the physical poles of a planet (Uranus is an example in our own solar system), so it is theoretically possible for auroras to happen over your main continent.

    **I'm no expert. Double check.
  3. IHaveNoName

    IHaveNoName Senior Member Community Volunteer

    Mar 15, 2016
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    Re; the weather... Livescience.com says:

    Re: The primates: Sounds about right. Lower gravity would enable them to be taller while still being light enough to glide. The largest bird, the albatross, has a 12-foot wingspan; the heaviest flying bird weighs around 45 pounds. I don't know how heavy your primates are, but it doesn't sound like they'd exceed 50-60 pounds, right?
  4. terobi

    terobi Senior Member

    May 20, 2015
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    Manchester, UK
    Note: Our sun is a yellow dwarf not a red dwarf. A red dwarf star is going to present some specific issues for you:

    1. Since a red dwarf is smaller and cooler than our sun, your planet will have to be very close to it in order for it to be in the 'goldilocks zone'. This may also result in it being tidally locked (i.e. your planet wouldn't have "days" at all - one side of the world would be in constant daylight, the other would be in constant darkness).
    2. Much of the light thrown off by a red dwarf star is towards the "red" end of the spectrum, and much of it would be infra-red light, rather than in the visible spectrum. Not only would humans perceive the planet to be very dark even in broad "daylight", but the native animals would be much better adapted to it. Their camouflage colouring and vision will both be influenced by this.
    3. Because much of the light emitted by the star is infra-red, and because it's so close, that's going to be a hell of a lot of IR radiation. Your human inhabitants would likely have to wear protective eyewear.
    Unless of course you really meant a yellow dwarf and that part was a typo. Then you're in the clear on these counts.

    Though your three moons (and the vast amount of water on the planet) are going to make for some interesting tidal patterns - you'd likely have incredible floods when the three moons are in alignment.
    tonguetied likes this.
  5. Guttersnipe

    Guttersnipe Member

    Mar 7, 2016
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    Vancouver, BC, Canada
    Some random comments (some of which have already been mentioned)

    • Slower rotation means less coriolis force, which means fewer and weaker cyclonic weather systems.
    • Although a slower rotation means greater heat difference, an almost-completely water-covered world means less separation of weather patterns and greater moderation of heat differences by the water. Overall, I think the weather would be milder.
    • Slower rotation means weaker magnetic field. However, Red dwarf means less harm from that. Unless the red dwarf is a flare star, which they often are.
    • Unless you really need RED, consider just going for a cooler but larger star. Our sun is a G5V, which references color (spectrum), temp, and size. A K4IV would be orange, slightly hotter, and bigger. You could put the planet farther out and still have the same climate.
    • The orbits of the moons are a potential problem. First, unless the orbits are exactly the same period, the moons will eventually collide. If the orbits aren't quite the same radius, the moons will eventually pass close enough to perturb each other. The rings of Saturn and most of the moons in the solar system are in a single plane because those perturbations tend to, over time, flatten out orbits.
  6. Robert Musil

    Robert Musil Comparativist Contributor

    Sep 23, 2015
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    One more thought on the moons: in order to not rotate, I think they'd have to be close enough to the planet to be tidally locked, right? Which means if they're the same size as Earth's moon they'd appear huge.

    Of course with the crazy orbits, more likely they'd be captured asteroids or something a lot smaller than Luna.

    ETA: The auroras occur over the magnetic poles of a planet, so all you'd have to do to have your aliens witness it was put one of the magnetic poles under their continent.

    One twist on this I thought of: Earth's magnetic poles have been known to shift position pretty rapidly, sometimes completely switching places within a few decades. It might be interesting for your mythology if this aurora suddenly disappeared/re-appeared, how would that affect your aliens' belief system? Plenty of drama and upheaval to be had, there.

    ETA (again): Thank goodness no one noticed the glaring error in this post :whistle: of course Earth's moon is itself tidally locked. So I guess you moons could be some distance away. But, if they are at two different altitudes the inner ones will have to be at least somewhat closer, probably.
    Last edited: Apr 18, 2016
    zoupskim and tonguetied like this.
  7. loonypapa

    loonypapa Member

    Apr 2, 2016
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    Man, I love these types of discussions.
  8. tonguetied

    tonguetied Contributor Contributor

    May 23, 2014
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    Central Florida: land of fire and sand
    Next we're going to find out there are mice that are actually pandimensional beings that claim to have commissioned this planet from Magrathea. And I agree with loonypapa, got to love these discussions, always amazed at the latent information hidden away among the forum members.
    terobi likes this.
  9. Inks

    Inks Senior Member

    Aug 24, 2015
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    Plenty of issues in some of the responses... the sun is a G-type main sequence star and it is not a "yellow dwarf" which is a horribly imprecise name because our sun's color is in fact - white. There is also some significant matters of the atmosphere and conditions about tidal-locking which should be looked up if one wants get technical about it, but.... this situation is impossible on a few counts. Just the three moons alone in such a system where the mass of our moon is already highly unusual means that the mathematics of having three such bodies would certainly create "interesting" effects on day/night cycle and tides, but the fact the moons would probably collide or break up is the key issue I have.
  10. Witchymama

    Witchymama Active Member

    Mar 10, 2016
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    Unless the entire system were engineered. Maybe artificial satellites, rather than naturally occurring ones.
  11. ShannonH

    ShannonH Member Supporter

    Nov 28, 2015
    Likes Received:
    Northern Ireland
    I'm thinking this thread is a good place to post my question as I feel it doesn't warrant its own thread.

    Currently I'm working on my attempt at a novel, I'm only four chapters in and have a hell of a long way to go. Today the 4th book in the Expanse series arrived at my doorstep. I opened it up to find on the 2nd page of the Prologue the same name of the planet I had chosen as one of the central locations for my story.

    Should I change it or just keep it?
  12. jannert

    jannert Retired Mod Supporter Contributor

    Mar 7, 2013
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    Can I mention something that bugs the crap out of me, when I read stories set on other 'planets?' So often the lifeforms the writers create are so limited. On a planet roughly the size of earth, with weather conditions that aren't all that dissimilar ...please don't have all the inhabitants be tree dwellers who are all similar to one another. Please don't have three plant species, five different animal species and one humanoid species that speaks the same language across the entire planet.

    The women on my planet are subservient to men.
    All the children on this planet must wear green shoes until they come of age.
    The hairy beasts on this planet will eat you and not ask questions.


    Think of the massive diversity of life that there is on earth. Earth is a huge place for those who inhabit it—despite being a mere speck in the firmament. Millions of creatures and plants evolved in different ways in different terrains, some cut off from major land forms by water, some by deserts, mountain ranges, etc. Think of all the different kinds of rocks. Think of the different ways water manifests itself (salt, fresh, underground, brooks, rivers, ponds, lakes, oceans, hot springs, cold springs, rain, fog, snow, steam.) If you're going to create another planet, please make it as diverse as ours! (Unless there is a very good reason why it's not—a reason that deserves a mention, if not a whole storyline.)

    If there are sentient beings (especially if they are primitive) they won't all speak the same language or behave in the same way, will they? We don't, even today. Even on our modern earth with the technological developments we live with, we still don't all look the same, hold the same views, live under the same political systems ruled by the same laws, or speak the same language. I suppose it's possible for a planet to have evolved to the point where this can happen, but it would take a bazillion years. It's much more realistic for a planet that can support life as we more or less know it, to have evolved in a similarly slow and incredibly diverse fashion.
    Last edited: Apr 18, 2016
    Robert Musil and Shadowfax like this.
  13. newjerseyrunner

    newjerseyrunner Contributor Contributor

    Apr 20, 2016
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    This is not possible, they can't be in the same orbit without the orbit destabilizing. In order to have moons that do not rotate, there must have been enough time for tidal friction to lock them, which means the orbits must be stable. Try putting them in a resonance instead.

    You would have strong winds from the equator up towards the poles and fierce winds on the border of light and dark, but during the night and day, there would not be much. The ocean will absorb most of the heat from the star while the ice reflects it. The ocean will retain heat during those long nights, so it should help the temperature with fluctuations.

    Less gravity would probable make them less dense, but how large creatures get will be determined by how much available energy there is in the ecosystem. More oxygen/sunlight will cause creatures to get bigger.

    Did I see somewhere that your planet is a red dwarf? That makes planet-wide auroras unlikely. There is no way to get an aurora over the equator, it'll line up with the spin of the planet. However, a strong storm on the star would push the aurora's south, so it could be visible to them occasionally. Religions tend to be more influenced by rare events than regular ones anyway (humans were afraid of comets.)[/quote][/QUOTE]

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