Past, present and future stars that can see Earth as a transiting exoplanet is a new paper by Dr. Jackie Faherty and Dr. Lisa Kalteneggar.
It reports that "In the search for life in the cosmos, transiting exoplanets are currently our best targets. With thousands already detected, our search is entering a new era of discovery with upcoming large telescopes that will look for signs of ‘life’ in the atmospheres of transiting worlds.
Previous work has explored the zone from which Earth would be visible while transiting the Sun1–4. However, these studies considered only the current position of stars, and did not include their changing vantage point over time.
Here we report that 1,715 stars within 100 parsecs from the Sun are in the right position to have spotted life on a transiting Earth since early human civilization.
With 1715 stars in the right position to have spotted life on a transiting Earth it is not unthinkable that we as a type 1 civilization are being watched by far more advanced alien civilizations Type 2 and Type 3 who maybe use these stars to monitor planet Earth for some reason without the possibility to discover them.
That we have not yet been able to make contact with the aliens may be due to the idea that radio waves are outdated technology, which is probably right. Just think about the idea that we are being watched without being able to interact with the aliens, because we yet discovered the preferred means of communications among the alien civilizations Type 2 and type 3.