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Exoplanet color theory

  1. Jun 14, 2017 #1
    Is there a guide, based on existing evidence, that I could use to infer realistically how color would be affected on alien worlds due to factors like star class, luminosity, atmospheric composition, etc? I'm planning to develop a not-too-too-distant future scenario where all the stars in question are stars we know a lot about, so how do I figure out simple things like what color the sky should be and how a blue/red star would alter skin tone and the like?

    Also, just out of curiosity, would the indigenous photosynthetic plant life of these worlds necessarily still be green?
     
  2. jcsd
  3. Jun 14, 2017 #2
    Here is a Venus image taken by the Soviet Venera 13 lander in 1982:
    surface.jpg
    Some atmospheric conditions can be determined by remote sensing, but we didn't know what the surface lighting would be until we got there.

    Here is a page that discusses star color:
    http://www.atnf.csiro.au/outreach/education/senior/astrophysics/photometry_colour.html

    Depending on the star, it could appear to look quite dark to us, yet still provide a lot on energy to the planets around us. It's main colors may simply not be in out visible spectrum.

    As far as vegetation: Of course we need to presume that there is any vegetation all. Given that, it would certainly be affected by available radiant energy. Even on Earth, underwater vegetation is affected. One key item is that photosynthesis as we know it, requires ionizing radiation - but hopefully not so ionizing that it destroys the foliage. So if color got too far into the IR or UV, there could be adaptation problems that require something more elaborate than simple photosynthesis.
     
  4. Jun 14, 2017 #3

    Drakkith

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    Yes, but it's not easy to account for all the different factors, especially the atmospheric composition. The easiest method would probably be to just assume a "clear" atmosphere except for some minor scattering of shorter wavelength light, like what happens here on Earth. Then you only need to worry about the type of star the planet orbits.

    If you're referring to the color of indigenous lifeforms, then there's no way to realistically know what their skin tone would be. Just look at the huge number of skin colors and tones of the animals here on Earth. They come in pretty much every color and tone imaginable.
     
  5. Jun 14, 2017 #4
    Actually, I was more curious how it would affect things we're familiar with already, to help show the otherness of the new worlds. Would a red dwarf illuminating an Earth-like atmosphere give everything a pinkish tinge? That sort of thing.
     
  6. Jun 14, 2017 #5

    Drakkith

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    Staff: Mentor

    That should be a little easier to figure out, but unfortunately I don't know the details of how to do so. :cry:
     
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