John Shepherd spent 30 years trying to contact extraterrestrials by broadcasting music millions of miles into space. After giving up the search he makes a different connection here on Earth. “You don’t need to translate if something can be felt through the soul, through the mind,” John Shepherd said in an interview with Pitchfork about his “strange, beautiful music” he chose. “There’s always that twilight zone in between reality and music that allows you a certain imaginary landscape—you can go there and figure things out, or just sort of relax and cruise with flow.”

Every night, he would choose a new album to broadcast to the stars, choosing some of our greatest music. His space DJ sets created an awe-inspiring soundtrack for the documentary, including songs by influential but lesser-known artists from around the world.

Check out this Spotify playlist to hear them all…

“I would start out, say, with Kraftwerk and maybe move on to Tangerine Dream and then Harmonia—a lot of progressive, creative groups,” he told Pitchfork. “Or I would be doing jazz, so maybe I’d start with Ornette Coleman and go into Charlie Parker and then Lee Morgan, following along that kind of line.

One Reddit user tapped the power of the 1.3 million strong Tip of My Tongue community, begging for the identification of one song that played during the documentary. It had a powerful space feeling, but they couldn’t identify the origin.

“I already heard that piece in the past, it is always used in space docs … the doc mentions other artists like Tangerine Dream, Kraftwerk, Harmonia, Fripp & Eno. But I didn’t find that piece in a quick search in some of the hits of those artists.”

Alert readers spotted the song as Alpha by Vangelis. Viewers first heard this song on Carl Sagan’s immortal Cosmos Series, episode two, to be exact, “One Voice in the Cosmic Fugue”—an episode focused on DNA as the master molecule of life.

TOR Books has a great essay about this episode of Cosmos, looking at how that single episode framed the question of alien life and the relatively recent discovery of DNA. “Aliens would really, truly really, not be anything like what we could ever think of,” wrote one reader. “The mind boggles at the idea of what alien life would be like. Why would it be anything remotely similar? No matter what our impressive imaginations can come up with, there’s really no way we could be correct. Makes finding alien life something more than just desirable. Wish I could see what it looks like. How it processes energy. Could it even perceive our existence?”