New Scientists reports on a new planetary model that describes the most probable color signature of worlds thriving with life: purple. We would be able to detect these planets in 2018, once the James Webb Space Telescope is in orbit.
According to the model developed by scientists at the Institute of Astrophysics of the Canary Islands, worlds thriving with alien microbes—a form that is supposed to be more common in the universe than complex, evolved life like ours—will look purple in the telescope.
To arrive to this conclusion they studied Earth during the Archaen eon, when Earth was thriving with purple bacteria. From there, they developed a model of what similar planets may look like in the telescope:
We find that purple bacteria have a reflectance spectrum which has a strong reflectivity increase, similar to the red edge of leafy plants, although shifted redwards. This feature produces a detectable signal in the disk-averaged spectra of our planet, depending on cloud amount and on purple bacteria concentration/distribution. We conclude that by using multi-color photometric observations, it is possible to distinguish between an Archean Earth in which purple bacteria inhabit vast extensions of the planet, and a present-day Earth with continents covered by deserts, vegetation or microbial mats.
Other scientists have created models that use similar models to detect the signature of other kinds of life, like plants and trees, using telescopes.
Purple worlds, people. Purple worlds.