ET watchers may be able to find an alien world through telescopes that may spot artificial lightings "out there."
A new study points to the possibility of finding extraterrestrial civilizations that may have also developed artificial lighting sources which our next generation telescopes can detect.
Researchers Abraham Loeb from Harvard and Edwin L. Turner of Princeton, said it is possible to peer into space and spot artificially illuminated objects, adding that current optical telescopes and surveys have the ability to see this amount of light at the edge of our Solar System and observations with large telescopes can measure a Kuiper Belt Objects spectra to determine if they are illuminated by artificial lighting.
Distinguishing an artificial illumination from solar illumination on KBO with typical albedo may be tricky, but the researchers said the existing telescopes and surveys can spot the difference as it will carry the dead give-away which is the spectral signature.
According to Loeb and Turner, our civilization uses two basic classes of illumination, thermal (incandescent light bulbs) and quantum (light emitting diodes and fluorescent lamps). "Such artificial light sources have different spectral properties than sunlight. The spectra of artificial lights on distant objects would likely distinguish them from natural illumination sources, since such emission would be exceptionally rare in the natural thermodynamic conditions present on the surface of relatively cold objects. Therefore, artificial illumination may serve as a lamppost which signals the existence of extraterrestrial technologies and thus civilizations," the researchers said.
Not all random light source detected where there should be darkness might be considered a sign of life, the study said, as there are many factors which could contribute to illumination, such as viewing angle, backscattering, surface shadowing, outgassing, rotation, surface albedo variations and more.
"City lights would be easier to detect on a planet which was left in the dark of a formerly-habitable zone after its host star turned into a faint white dwarf," Loeb and Turner say. "The related civilization will need to survive the intermediate red giant phase of its star. If it does, separating its artificial light from the natural light of a white dwarf, would be much easier than for the original star, both spectroscopically and in total brightness."
However, the researchers said that while they are not expecting that civilizations are thriving at the edge of our solar system, the study is just a suggestion and a new way of looking at things, as well as possible exercises for future telescopes and studying exoplanets.
"This method opens a new window in the search for extraterrestrial civilizations," Loeb and Turner write in their paper "Detection Technique for Artificially-Illuminated Objects in the Outer Solar System and Beyond."
"The search can be extended beyond the Solar System with next generation telescopes on the ground and in space, which would be capable of detecting phase modulation due to very strong artificial illumination on the night-side of planets as they orbit their parent stars," they concluded.