Spacecraft such as Voyager, Pioneer, and New Horizons, launched decades ago to explore outer space, are now in interstellar space, and Pioneer 10 will have the earliest chance of encountering a star in 2029.
The old trope about signals from Earth reaching other civilizations receives an interesting twist when you ponder just what those signals might be. In his novel Contact, Carl Sagan has researchers led by Ellie Arroway discover an encrypted TV signal showing images from the Berlin Olympics in 1936. Thus returned, the si