It is quite possible that extraterrestrial life could be purple, at least according to a new study by postdoctoral researcher Edward Schwieterman at the University of California, Riverside, and microbiologist Shiladitya DasSarma of the University of Maryland School of Medicine.
As Live Science report, the first life here on Earth might have had a purple tinge to it as these lavender organisms slowly discovered that they could create energy by using the sun, long before green plants did the same. Because of this, DasSarma believes that alien life could be doing exactly the same thing elsewhere.
“Astronomers have discovered thousands of new extrasolar planets recently and are developing the capacity to see surface biosignatures in the light reflected from these planets.”
Scientists already have the capability to see green organisms in space, and DasSarma believes that scientists need to start focusing on purple organisms now too. The suggestions that early life on Earth was purple is hardly a new claim, and DasSarma and his team originally suggested this theory back in 2007, leading them to speculate that the same may be true of extraterrestrial life, with it likely to also be purple.
The reason for this claim is really quite straightforward. Photosynthesizing algae and plants create their energy through the sun by using chlorophyll, but green light is not absorbed. Because green light is particularly rich in energy, DasSarma and his colleagues found this strange, reasoning that perhaps when chlorophyll synthesizers first began to evolve, there may have been something else that was able to successfully use that particular area of the visible spectrum.
Single-celled organisms — that are known as Archaea — and bacteria even now still use retinal light-harvesting and these organisms, which are purple, are so common on Earth that they can be found on leaves, oceans and even the Antarctic Dry Valley. These pigments of retinal are also used by even more complex animals, and the discovery that these pigments are so common in so many different organisms suggests that their evolution most likely started very early on Earth.
But moving past the idea that early life may have been purple on Earth, DasSarma and Schwieterman believe that purple organisms perform quite well, which means that extraterrestrial purple life may also be thriving elsewhere. And if this is the case — and these alien organisms are harnessing their energy by using retinal pigments — scientists should be able to locate them if they are hunting for the correct light signatures.
As Schwieterman explained, “If these organisms were present in sufficient densities on an exoplanet, those reflection properties would be imprinted on that planet’s reflected light spectrum.”
The new study which suggests that extraterrestrial life could be purple has been published in the International Journal of Astrobiology.