Researchers have speculated that Earth-like planets with two suns could host black and grey plants.
Credit: University of St. Andrews
In M star radiation habitats, vegetation may have more photosynthetic pigments in order to make use of a fuller range of wavelengths, giving them a ‘black’ appearance. Pictured are terrestrial examples of a dark plants (and flowers).
Credit: University of St. Andrews
FIFE: A sky with two suns is a favorite image for science fiction films, but how would a binary star system affect the appearance of life evolving on an orbiting planet?
In a new study, researchers have assessed the potential for photosynthetic life in multi-star systems with different combinations of sunlike stars and red dwarfs to figure out what plants might be like. The team has speculated that on an Earth-like planet with two or three suns, the vegetation may appear black or grey.
"If a planet were found in a system with two or more stars, there would potentially be multiple sources of energy available to drive photosynthesis," said PhD student Jack O'Malley-James from the University of St. Andrews in Scotland.
"The temperature of a star determines its colour and, hence, the colour of light used for photosynthesis. Depending on the colours of their star-light, plants would evolve very differently."
Adapting to multiple suns
Photosynthesis - converting sunlight into energy - is the basis for the majority of life on Earth. It is the energy source for plants and, accordingly, animals higher up the food chain.
With multiple light sources, life may have adapted to use all suns, or different forms may develop that choose to use one specific sun.
This may be the more likely option for planets on which parts of the surface are illuminated by only one sun for long periods of time.
Assessing a combination of scenarios
Sun-like stars are known to host exoplanets and red dwarfs are the most common type of star in our Galaxy, often found in multi-star systems, and old and stable enough for life to have evolved.
Over 25% of Sun-like stars and 50% of red dwarfs are found in multi-star systems.
In the team's simulations, the Earth-like planets either orbit two stars close together or orbit one of two widely separated stars. The team has also looked at combinations of these scenarios, with two close stars and one more distant star.
Exotic forms of familiar plants
"Our simulations suggest that planets in multi-star systems may host exotic forms of the more familiar plants we see on Earth. Plants with dim red dwarf suns for example, may appear black to our eyes, absorbing across the entire visible wavelength range in order to use as much of the available light as possible," said O'Malley-James.
"They may also be able to use infrared or ultraviolet radiation to drive photosynthesis. For planets orbiting two stars like our own, harmful radiation from intense stellar flares could lead to plants that develop their own UV-blocking sun-screens, or photosynthesising microorganisms that can move in response to a sudden flare," he continued.
O'Malley-James will be presenting his results at the Royal Astronomical Society (RAS) National Astronomy Meeting in Llandudno this week.
With the University of St. Andrews
Plants in outer space on a planet in a multi-star system?
On the face of it, this seems pretty silly. Planets in solar systems with more than one star would have chaotic orbits that would make it very difficult for the planet to be in a habitable zone. Also the evolution of plant life on Earth took so many fortuitous steps that would make the existence of ET plants very lucky: the eukaryotic cell itself was a product of endosymbiosis of first an archaea and bacteria, then a purple bacteria (mitochondrion); then the unicellular algae was born after symbiotic relationship with cyanobacteria; then for land colonization the multicellular protoplant developed symbiotic relationships with fungi. All these steps were necessary before the existence of terrestrial plants were possible on Earth. I'm of the opinion that life at the level of bacteria may be possible in the universe, but multicellular animals and plants are less likely. The habitable zone shrinks greatly around a star in order for the latter to evolve. This kind of "research" on the surface of it is extremely speculative. You won't catch too many biologists and many fewer evolutionary biologists going on record (esp. in a peer reviewed journal)with such speculation, but the literature is rife with astronomers, astrophysicists, and planetary scientists doing just that.
Well, what if you have a
Well, what if you have a binary system whose suns have a much higher intensity than our own, and a rocky planet further out than the earth. Could that not, hypothetically, result in a planet that has approximately the same surface temperature as the Earth? And if you're far enough away, the gravity you feel from the suns basically only felt from the two stars' centers of mass, right? It's highly improbable to find something like this, but I'm not as skeptical of the idea.
Open up your mind a little...
The process by which life developed on Earth will be by no means the same as that of another world. There are examples of this fact in our own biosphere. The squid and the mouse both have eyes with a retina, cornea, and lens but the two couldn't be further apart.
Life may or may not exist on other worlds. If it doesn't, which I find rather difficult to believe, then the argument is over. However, since a negative can never be proven without all of the facts, I would tend to believe it is both out there and complex.
Unless you are to assume humanity is the center of all things, then there is no reason to assume we are more or less complicated then any extraterrestrial life. Why haven't we heard from any of them? That would be an easy one. On Earth here, we could make as much noise (radio, optical, etc.) as we like and still not drown out the din of our star and its neighbors.
The fact that life exists under a wide range of environmental conditions on Earth should be enough proof that it is possible elsewhere. After all, there is nothing inherently peculiar about Earth. Every generation scientists discover that the boundaries they've placed upon theory have been too narrow and have been forced by evidence to expand the limits to encompass the new model.
Bilateral symmetry, photosynthesis, and intelligence may seem complex, but I bet the game has only started.
As far as biologists not going on record about life on other worlds, maybe it is about time. Maybe the theorists should come out of hiding and participate in the discussion. I am sure their wisdom would only add to the discussion.
I don't believe in the word can't.
@Visitor I'm of the opinion
@Visitor
I'm of the opinion that your view is too narrow. Look at the seemingly infinite number of stars in the sky. Also note that is it reasonable to assume that there are plenty more that we are just unable to see because they are too far away.
I am dismayed by your presumption that there is likely no life beyond bacterial forms. Life is complex and so are the means by which it evolves. "ET" life does not need to comply with our perceived view of the universe from our limited vantage point. We are mere bacteria in the scale of the universe and we must remain humble. The chaotic series of events that led to our existence should be proof enough that it is entirely possible that several other planets evolved complex life.
something to think about
they "could" also grow pineapples....
Human perceptions...
It is unfortunate that humans have generally not advanced in "thought" beyond looking at our Universe in human terms. We probably have found "alien" life but I suspect we are not astitute enough (yet) to realise we have. I sometimes find it amusing that scientific thinking when it comes to 'finding alien life..' is confined to looking and listening for "life". Perhaps we should imagine that we are "ants" looking for NOT other ants but something vastly different. Perhaps when we find and understand the evidence for this 'life' the best we would be able to muster is a feeble grunt as we fall down in submission....SpyRos