According to Nancy Y. Kiang (biometeorologist at the NASA Goddard Institute for Space Studies) green aliens are so passé. Well, she may have a point. In a fascinating article in Scientific American (April, 2008), Kiang tells us that “light of any color from deep violet through the near-infrared could power photosynthesis.” For instance, the cooler type M stars (red dwarfs) are feeble and planets receive less visible light. Plants might need to be close to black in color to absorb as much light as possible. Young M stars fry planetary surfaces with ultra-violet flares, so many organisms would likely be aquatic to survive. Our sun is type G, and on Earth green generally dominates the color of living plants. Around F-stars, hotter and bluer than our sun, plants might get too much light and would need to reflect much of it, so they would tend to absorb blue light and might look green to yellow to red or violet.
