Scientists looking for life on other planets have got a new strategy now. Instead of sending radio transmissions, low energy pulses, and exploration probes, they would be looking at something else – light from alien cities.
This new direction in the eternal search for extraterrestrials follows from the assumption that aliens, like humans need light to see at night and would gladly illuminate their cities (if there are any) during the hours of darkness. And even at astronomic distances, these lights would be different from natural sources of light. This new way for finding aliens in space is the brainchild of theoretical astrophysicist Abraham Loeb of Harvard University and astronomer Edwin Turner from Princeton University. Interestingly, they hit upon this novel way while attending a conference in Abu Dhabi where a tour guide casually mentioned that the emirate of Dubai is so bright at night that one can see it from space!
This is quite a change from the traditional SETI methods that looked for alien radio transmissions. But the question is how to recognize light from such cities? According to Loeb and Turner, the change in light reflected from such planets can be the distinguishing factor. And assuming that such a planet revolves in an elliptical orbit around its star, the reflected light will change with distance from the star. However, the artificial light will remain constant. This change in light flux can distinguish brightly lit alien cities in the deep unknown expanse of space.
And in order to see whether their theory holds water, Loeb and Turner, calculated that a brightly lit city like Tokyo (50 kms wide) situated in the Kuiper Belt would be easily visible with existing telescopes on Earth. The Kuiper Belt is a region containing more than a trillion comets and is at the edge of our solar system at a distance of 50 astronomical units. And with bigger and better telescopes in the next couple of years, you can surely hope to catch a glimpse of a hereto unknown race of aliens enjoying a night out in some distant planet.