The search for signs of intelligent, extraterrestrial life continues but a new study suggests exactly where to start. Researchers, as we know, have identified and characterized many possibly habitable alien planets. They did this by utilizing the "transit method". The transit method analyzes how parent stars' light changes when orbiting across these stars' faces from Earth's perspective. This is accomplished via NASA's Kepler space telescope. link
Logically, intelligent aliens could possibly use this same strategy to discover Earth and learn that it has the ability to support life.
Rene Heller, of the Max Planck Institute for Solar System Research in German says, "It's impossible to predict whether extraterrestrials use the same observational techniques as we do...But, they will have to deal with the same physical principles as we do, and Earth solar transits are an obvious method to detect us."
However, according to the rules of cosmic geometry, Earth's solar transits are visible from a limited swath of the sky. This has been dubbed by Ralph Pruditz, a professor of physics and astronomy at McMaster University in Canada, the "transit" zone.
Through this understanding, SETI (Search for Extraterrestrial Intelligence) should focus on this particular swath of space in order to gain the highest chance for contact.
The transit zone contains roughly 100,000 stars, which means there's no shortage of "potential targets for SETI scientists' radio telescopes."