Do aliens exist and are they advanced enough to create entire civilizations? Scientists are continuing to search for life on other planets, and now, astronomers have discovered the best places to search for aliens.
NASA's Kepler spacecraft has already discovered more than 1,000 worlds since its launch in 2009. But narrowing down which of these planets are most likely to host extraterrestrial life can be a difficult task. That's why researchers are looking at what may make a planet more or less likely to have aliens on its surface.
In this case, researchers argue that those searching for alien intelligence should target exoplanets from which Earth can be seen passing in front of the sun. By studying these transits, civilizations on these planets could see that Earth has an atmosphere that has been chemically altered by life. This, in theory, would give aliens a higher motivation to contact us.
About 10,000 stars that could harbor these planets exist within 3,260 light-years of Earth. Future searches for signals from aliens could target these planets. With that said, the zone of space in which Earth transits would be visible is a relatively narrow strip and gets even narrower if restricted to geometries in which the Earth passes less than half a solar radius from the sun's center, which gives a transit that should be easily visible if aliens have a tool similar to Kepler.
About 82 sun-like stars in this zone are within 3,260 light-years of Earth. Since not all of the stars in this region have been discovered, the number of stars that probably exist is more around 10,000. If these stars have planets and if the planets have intelligent life forms, they could have started beaming signals toward us - which means we should focus on searching for radio signals in these areas. In other words, the best way to discover alien life may be to look at planets that may have extraterrestrials searching for us.
Of course, focusing on these exoplanets doesn't necessarily mean that we'll find life there. However, it's a tool that can be used to help with the search of life on other planets. It also is a way to focus where we should direct satellites that hunt for signals from extraterrestrial life.
