Black Plant Life Could Thrive On Other Planets

Most plants capture sunlight. And the results are usually green. Because in photosynthesis, plant chlorophyll uses wavelengths of blue and our sun’s abundant red, and reflects green. But what if—as many sci-fi scenarios suggest—there’s an Earth-like planet with multiple suns? Researchers at England’s University of St. Andrews say that photosynthetic life on such a planet might end up as a drab black or gray. Or even with a high SPF.

A quarter of all stars like our sun actually exist in multi-star systems. Plants on a planet with two sun-like stars could need protection against too much radiation—they might evolve their own UV-blocking sunscreens.

Or a planet with two stars may have one sun-like star, along with a red dwarf star that’s also common in multi-star systems. Any photosynthetic life would be adapted to take advantage of the available light waves.

Plants that relied at times mostly on the dim red dwarf might need light from all across the visible spectrum. They wouldn’t reflect any wavelengths, so they’d appear black. These ideas were presented at the current Royal Astronomical Society meeting. So for healthy eating on some other planets, try the leafy dark salad.

—Cynthia Graber