The Color of Plants on Other Worlds
On other worlds, plants could be red, blue, even black
The Color of Plants on Other Worlds
- EARTH PLANTS Our sun is a type G star. Although the energy spectrum of sunlight at Earth's surface peaks in the blue-green, the photosynthetic pigment chlorophyll preferentially absorbs red and blue light and carotenoid pigments (which produce the vibrant reds and yellows of fall foliage). For our plants, it's easy to be green.
- PHOTOSYNTHESIS Light-harvesting pigments in photosynthetic organisms preferentially absorb photons of particular colors, scattering the rest. Plants on Earth get most of their energy from blue and red photons and scatter or reflect green photons. The photon energy gets transmitted along networks of pigment molecules to a reaction center, which splits water to obtain energetic electrons for biochemical reactions.
- VARIOUS TYPES OF F-STAR FOLIAGE If it isn't easy being green on Earth, where chlorophyll is well tuned to absorb most of the energy in our sun's yellow light, imagine the difficulties elsewhere in the galaxy. Plants growing on worlds around cooler, brighter or more tempestuous stars would need to rely on red, blue or even black pigments to survive. That insight offers astronomers new clues about what to look for in their search for extraterrestrial life.
