Confession: I am a huuuge science fiction nerd. That's right, when I am not reading and writing about botany or ecology, I like to unwind with the works of authors such as Arthur C. Clarke, Robert Heinlein, and David Gerrold. By and large my favorite sci fi topics are those dealing with aliens. Pondering alien ecology and culture is one of the best thought experiments. This obsession definitely bleeds into my day to day life. I have to admit that one of my greatest hopes is that we will discover life elsewhere in the universe. I'm not alone in this either. Many have devoted their careers to the search for extraterrestrial life.
As any good scientist knows, we have to temper our expectations to the realm of reality. That being said, we have a very small sample size to base our expectations on. We only know of the carbon based life that we are part of. As such, this colors the way in which we think and search. Our search for habitable planets for instance takes into account all of the parameters that make Earth special. By looking for planets like ours, we are at least narrowing the possibilities to conditions we know can support life (as we know it). However, we can't let Earth be the only lens to color our search. That is where researchers such as Nancy Kiang come in.
Nancy's work finds her modeling the conditions, both solar and atmospheric, of other planets in order to see which of them may be suitable for photosynthetic life. Certainly photosynthetic life isn't the only possibility out there but it sure is a good place to start. As on our planet, photosynthetic organisms are able to harness energy from the giant nuclear fusion reaction we call the Sun and turn that into food. However, not all suns are like ours. Alien "plants" may have to take advantage of stars very different from our own.
This is where Nancy comes in. By modeling the conditions on the surface of hypothetical planets, she is able to identify the various wavelengths of energy that would be available to any organism primed to take advantage. For instance, the radiation given off by red dwarf stars would only provide a mere fraction of the visible light given off by our sun. "Plants" on a planet orbiting a red dwarf would need to absorb as much light as possible in order to photosynthesize properly. As such, these alien "plants" would likely appear black.
Absorption is the key to this concept. The reason plants on Earth appear green is because that is the wavelength they do not absorb. Despite the fact that green light is the most abundant on our planet, it is quite weak in comparison to wavelengths of red and blue. Terrestrial plants absorb reds and blues and reflect green, which gives them their characteristic color. Because of this, Nancy and her team feel that it would be highly unlikely to find blue photosynthetic organisms elsewhere in the universe. Its simply too powerful a wavelength to not be utilized.
Still, until we find evidence of life on other planets, this is all a fun thought experiment. However, before you go writing off the work of researchers like Nancy Kiang as mere entertainment, remember that without such scientific speculation, we are left in the dark on exactly where and how to search for life elsewhere in the universe. By working out the possibilities of life on other planets, researchers like Nancy are helping to focus the search for extraterrestrial life.
Photo Credit: Richard Mosse