Members of an advanced species from another planet might be looking at the stars and ask themselves, ‘are we alone in the Universe?’. As wild as such a scenario may sound, many scientists believe that judging by how huge the Universe is, alien life should be pretty common out there across the vast ocean of space.
But since it’s hard to believe that humanity ever had an encounter with an alien species, skeptics will always ask, ‘if aliens exist, where are they and why aren’t they here yet?’. At least for the first part of the question, Cornell astronomer Lisa Kaltenegger and Lehigh University’s Joshua Pepper are ready to provide an answer by a different way to approach the problem.
Look how visible Earth is from exoplanets
Oddly enough, this method will provide the answer to the possible locations from which aliens might be looking at our planet.
“Let’s reverse the viewpoint to that of other stars and ask from which vantage point other observers could find Earth as a transiting planet,” Lisa Kaltenegger explained, the lead author of the study. “If observers were out there searching, they would be able to see signs of a biosphere in the atmosphere of our Pale Blue Dot,” she explained, “And we can even see some of the brightest of these stars in our night sky without binoculars or telescopes.”
Researchers discovered 1,000 stars within about 300 light-years away from us that are capable of hosting planets from which Earth could be detected by using the transit method (as the planet passes in front of its host star relative to the observer). Of course, it’s mandatory for some advanced alien life forms to exist on those planets for ours to be detected.
For a planet to have any theoretical chance of hosting life of any kind, having liquid water on its surface is mandatory. The required conditions are a lot more numerous, but the distances to other solar systems are, for the moment, way too large for humans to cover.