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Thread: WIP - HELP? Pretty please?

  1. #21
      Jalyha is offline
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    Quote Originally Posted by Veldehar View Post
    Speaking of projections... if you haven't checked it out yet, a cool little freebie from NASA. Handy little thing.

    http://www.giss.nasa.gov/tools/gprojector/

    It does look handy. I'll try it and see if it helps my horrible little map.


    Quote Originally Posted by Azelor View Post
    Isn't it possible to squeeze an equirectangular projection in a square ? I don't know if it's possible but Hai-Etlik surely knows about this ...
    Huh?

    The easiest way is to make the submoon orbit the larger moon. If it's the smaller moon, well let's just say that the submoon would be more like an asteroid. And it would be hard to see it from the planet (I guess).I know it's possible but I haven't been into the details. I bought a astrophysic simulator called Universe sandbox on Steam and it worked. It's possible to get arround this n body problem but Binary star systems are much more complicated...
    Wouldn't that depend on the exact size of the moons? :s Does your simulator allow you to put in precise measurements? Can I borrow you to test my moon issues?

    Moon T should be stable otherwise it would already have disappear. Either by crashing on moon C or to become the third moon of the planet.
    From what I understood, that will always happen, eventually...


    I already saw your map on another topic... So far, it seems fine to me. I have to admit I have a problem when it comes to world construction. I started with a region with no idea of the surrounding. Yet I find myself ''forced'' to fill the map because things like climates and plates does not make much sense if the world is empty.
    Yeah... I start with more like.. a photograph of the area in my head. :/ I haven't even been successful with mapping a small region yet, lol.

  2. #22
      Azelor is offline
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    Well, equirectangular (or plate carrée) is a rectangular shape projection. But... a software names Fractal terrain display a projection called equirectangular DIN formated where the proportions are 1,41 instead of 2... So I was simply wondering if it's possible to make it a square.


    I can try it in the simulator with precise number, but it's not flawless.

  3. #23
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    Quote Originally Posted by Azelor View Post
    Well, equirectangular (or plate carrée) is a rectangular shape projection. But... a software names Fractal terrain display a projection called equirectangular DIN formated where the proportions are 1,41 instead of 2... So I was simply wondering if it's possible to make it a square.


    I can try it in the simulator with precise number, but it's not flawless.
    I don't know what you need so here's what I have:

    Sun: About the same as our sun, which is:
    Surface temperature: 5,778 K
    Mass: 1.989E30 kg
    Radius: 695,500 km (1 R☉)

    Planet N:
    Radius: 26,187 miles (42,143.9 km)
    Mass: 62.16 Earth mass
    Surface Area: 8.62 billion square miles (13.87 billion km2
    Distance from sun: 316,700,000 miles (509,679,000 km)

    Hill Sphere ~ 5.45 million km

    Moon B:

    Orbits planet N at a distance of: 420,793 km
    Circumference: 8,918 miles

    Moon C:

    Orbits planet N at a distance of: 776,938 km
    Circumference: 7,839 miles

    Moon (subsatellite) T:

    Orbits Moon C? at a distance of: 58,214 km
    Circumference: 2,983 miles


    All of this was just me playing with numbers (which I'm not very good at, so there's probably something wrong) and can be tweaked. I basically just did this up in a bout of insomnia one night to see if it was at least partially plausible.... and for how long



    So... that's for simulation purposes. What I really need is anywhere from 150 - 400 years with 3 visible "moons" or satellites in the sky and after that, I need a lunar train-wreck.

    Cause train wrecks are fun.

    For the map of the planet, I HONESTLY don't care what's on the other side of the globe, but I'd imagined it up until now as all (or mostly) water. And as I said, I don't really care too much about the shape/placement of the continents, except for the "devil's walk" (string of islands near 1 south-eastern continent) and that one continent is called "the devil's hat" because it has "horns".

    I've NO idea what I'm doing with the rest of them

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    Ok so I made some tests:

    Your planet is far from it's star : 3,41 times farther than the Sun-Earth distance.
    1 revolution around the star takes 6,27 years
    the global mean temperature is around -117 C, if the atmosphere is the same than on Earth
    the diametere of the planet is nearly 4 time Earth's
    gravity, I tried to calculate it and I got 1,54 (on Earth it's 9,81) so it's 6,37 time less. I think I made a mistake.
    density would be around 1,17 g/cm3 (on Earth it's 5,52) that could be a problem , maybe a weaker magnetic field. But since water is more dominant than on Earth, it could explain a bit of the difference.

    Moon B:
    mass 2,27 moons (with same density as our Moon)
    takes 4 days to obrit around the planet (not sure if that part make sense since our moon takes 28 days and is more or less at the same distance). but at the same time, since both objects are more massive I think B need to move faster to compensate for the increased gravitational pull. Does it make sense ?

    moon c: 1,54 moons
    take 9,85 days

    Moon t : orbit seems more or less stable at 12 000 km but it's pretty much the limit. The hill sphere of moon c is bigger than that but even at 15 000 km, it take less than a week before it change of orbit.
    mass : around 0,03 moons
    orbit around moon c in 1,11 day


    That was the simulator, I did around 150 days. The bodies rotate so fast that 150 days is long enough to know how stable they are. If I increase speed too much the simulator can't get the orbits right and planets get ejected with no reasons. Like a sling.
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    Crudcicles.


    The moon stuff is exactly what I wanted it to be... and yes, the orbit of moon B makes sense My people mark "weeks" as 4 day periods.

    Even the orbit of moon T being at the absolute limit is perfect.

    And I don't think you made a mistake on the gravity... at least, it's close enough to what I estimated for it not to be worrying...

    The problem is... the temperature is way too low!! (I don't know how to calculate that?) Can't live in those temperatures. I could move it closer to the sun to heat it up, but that would mess with all the gravity crap, which changes the hill spheres of the planet, which might affect my moons, which means... starting over. :/

    How else can you increase a planet's temperature, without killing everything off? >.<

    Starting to think my story won't work

    Thank you for running the simulation either way. The fact that my moons are doing what I want them to do means, at least, that I'm calculating everything properly (or close enough). So it really does help a LOT.

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    Wow. This thread is full of a lot of great information!

  7. #27
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    Oh I forgot to say that the Hill sphere of the planet was about 20 millions km, not 5. If the simulator is right, 5 millions km would be when the planet is about 149 millions km from the star. Same as Earth.

    To answer your question, the albedo is a number that indicate how much of the light if reflected back to space. Light colours reflect light and the dark ones absorb it. It says here that snow can reflect between 40 and 85% while it's around 8 % for water covered areas. Earth's albedo is around 30% but more oceans means a lower albedo.

    We also discussed other ways to create heat on a cold world. This includes the friction generated by the gravitational pull between different bodies that could heat the planet. But I think it’s mostly volcanic activity and would not heat the atmosphere much.

    But low gravity and low planet density seems problematic too. Not that life is not possible but if far different than on Earth. It would be very easy to fly. So easy... I wonder what would happend to the atmosphere.
    Last edited by Azelor; 01-19-2014 at 11:03 PM.
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  8. #28
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    Uh.... Earth's hill sphere is 1.5 million km, not 5 million?

    Yeah, I've been going over the other stuff and coming up with tons more problems. I think I may have to start the math over from scratch

    (IF I can get it to work at all, it won't affect anything I've already written)

    OR I could scrap the danged story and start that over...

    Hmmm... 10 chapters of writing or 60-something pages of calculations... ?

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    The map looks reasonable for a Mercator projection Mercator is infinitely tall and so you have to chop off the poles, where you do so is arbitrary so you can get a square if you want to. The "Google Spherical Mercator" used by most web slippy maps does this for instance.

    The aspect ratio of equidistant cylindrical can be adjusted by changing the standard parallels. The aspect ration for a full globe map in equidistant cylindrical is 2:1 when the standard parallels are 0° (Plate carree/equirectangular), and it can be adjusted to anything lower than that, including 1:1 when the standard parallels are at cos⁻¹ 0.5 = 60°
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    Quote Originally Posted by Hai-Etlik View Post
    The map looks reasonable for a Mercator projection Mercator is infinitely tall and so you have to chop off the poles, where you do so is arbitrary so you can get a square if you want to. The "Google Spherical Mercator" used by most web slippy maps does this for instance.

    The aspect ratio of equidistant cylindrical can be adjusted by changing the standard parallels. The aspect ration for a full globe map in equidistant cylindrical is 2:1 when the standard parallels are 0° (Plate carree/equirectangular), and it can be adjusted to anything lower than that, including 1:1 when the standard parallels are at cos⁻¹ 0.5 = 60°

    Y U give me more math? *cries*


    Actually, that's very helpful. And next time, I'll just do it right in the first place (or claim later "It's a Mercator projection!" )

    I'm glad I was confused on this one. It opened up a lot of learning

    So.... guess I'll get back to the drawing board...

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