(Before It's News)
If wanting to find an alien planet having advancing technology, thus having major civilization, perhaps the simplest way would be to try detecting anything broadcast from there, such as TV & radio. That should likewise be the easiest way any not too far remote aliens could discover that Earth has technology now advanced into electronics (and thus most likely into many other classes of advanced developments).
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Source:
http://www.prophet666.com/2013/11/how-to-detect-alien-radio-broadcast.html