Sorry, Little Green Men: Alien Life Might Actually Be Purple
Purple may be a likely color for extraterrestrial organisms, research suggests
Nazarii Neshcherenskyi/Getty Images
If we discover alien life, what will it look like?
We have no way of knowing, but the hunt for extraterrestrial life can now include purple bacteria, according to a group of astronomers who are recording the chemical makeup unique to the lavender-hued organisms. These microbes may have dominated Earth early on in our planet’s history and are well-suited to emerge on faraway worlds that circle dim red stars smaller than our sun, a new study suggests.
The latest cataloging effort is in part “to create a database for signs of life to make sure our telescopes don’t miss life if it happens not to look exactly like what we encounter around us every day,” study co-author Lisa Kaltenegger of Cornell University said in a statement. “Purple bacteria can survive and thrive under such a variety of conditions that it is easy to imagine that on many different worlds, purple may just be the new green.”
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On Earth — the only planet we know of where life exists and thus our best guide in the hunt for extraterrestrial life — life sustains itself on oxygen-producing photosynthesis driven by chlorophyll, the familiar green pigment utilized by most organisms to harness sunlight. This wasn’t the case until roughly 2.4 billion years ago, when tiny blue-green algae called cyanobacteria, the first known species to photosynthesize, began using chlorophyll to harness sunlight and carbon dioxide for metabolic energy, and released oxygen as a byproduct.
Prior to that, microorganisms generated metabolic energy by…
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