Color me black? Alien planets with two suns sprout dark trees.
If Tatooine had trees, would they be black? Scientists say that a planet with two suns might have black or gray plants, not green. Why is that?
Luke Skywalker leaves his home, heading toward the setting twin suns of Tatooine. This still photos is from Star Wars: Episode IV - A New Hope.
Lucasfilm Ltd. & TM
Luke Skywalker's home planet of Tatooine is a vivid desert world under two suns, but it may be missing one key detail: black trees.
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According to a new study, Earth-like alien planets with multiple suns may host trees and shrubs that are black or gray instead of the more familiar green.
It all depends on the particulars of the light available for photosynthesis, the process by which plants convert sunlight into energy. Photosynthesis produces oxygen and ultimately provides the basis for most life on Earth. [The Strangest Alien Planets]
Luke Skywalker's home planet of Tatooine is a vivid desert world under two suns, but it may be missing one key detail: black trees.
According to a new study, Earth-like alien planets with multiple suns may host trees and shrubs that are black or gray instead of the more familiar green.
It all depends on the particulars of the light available for photosynthesis, the process by which plants convert sunlight into energy. Photosynthesis produces oxygen and ultimately provides the basis for most life on Earth. [The Strangest Alien Planets]
"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," study lead author Jack O'Malley-James, of the University of St. Andrews in Scotland, said in a statement. "The temperature of a star determines its color and, hence, the color of light used for photosynthesis. Depending on the colors of their starlight, plants would evolve very differently."
Green not a given
Most plants on Earth are green because they enlist a biomolecule called chlorophyll to drive photosynthesis. Chlorophyll absorbs sunlight in the blue and red wavelengths most strongly, which makes sense; blue light is extremely energetic, and our sun throws off red light in great volumes.
Chlorophyll reflects sunlight around the green part of the electromagnetic spectrum, on the other hand, which is why leaves look green to us.
But there's no guarantee that plants on alien worlds would do things the same way. Alien shrubs might be orange or red, for example, depending on what wavelengths of light are available to them. [A Field Guide to Alien Planets]
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