This could serve as a subplot for a sci-fi story: alien are trying for decades to contact by sending out encoded messages. Because the first sentinels are power

This could serve as a subplot for a sci-fi story: alien are trying for decades to contact by sending out encoded messages. Because the first sentinels are powerful AI, and only analyzed the data pattern, humanity was ignorant of the messages for decades. Until one day, a young astronomer played with the data and asked the AI to plot and visualize in many different ways, just for fun and suddenly realized the hidden images encoded in the messages :)