The notion of writing a concept album about the contents of the Milky Way is a go-big-or-go-home kind of proposition for any songwriter. Many would blanch at the idea of even attempting such a monumental task, fearing the inevitable charges of gross pretentiousness or unseemly creative overreach.But for Sufjan Stevens, it seems like a perfectly organic (and celestial) extension of his work. Sure, he may have seemed more like your average winsome American singer/songwriter type at the beginning of the century, toting an acoustic guitar and performing songs that fit into the noble lineage of Cat Stevens, Nick Drake, and others who have a snug home on bastions of mellow playlists like SiriusXM’s The Coffee House. Yet time and again, he’s proven to be a maximalist at heart. He’s continually pursued much grander ambitions than most of his peers could ever consider, whether it means creating impossibly lush album-long tributes to American states (though he won’t be doing all 50, as he once promised in jest) or enlisting a string quartet to remake one of his earlier albums in classical form (on 2009’s Run Rabbit Run). He’s also revamped dozens of hoary old Christmas carols into bold new forms, doubled down on cover versions that may be more sonically extravagant than the originals (just hear his takes on Joni Mitchell’s “Free Man In Paris” and Arthur Russell’s “A Little Lost”) and generally felt free to extend his sound palette and songs’ running times to extremes that may have daunted Emerson, Lake, and possibly even Palmer.All the while, Stevens has been similarly fearless and expansive when it comes to his lyrics, intermingling his references to and explorations of the Christian mysticism of his youth with more idiosyncratic mythologies that he constructs out of personal experiences (like the troubled family history he recounts in Carrie & Lowell, the 2015 masterpiece he named after his parents) or the strangest corners of America’s past (as in so many of his odes to Michigan and Illinois).So a project as cosmic as Planetarium seems right in the man’s wheelhouse. A new collaborative album that simultaneously evokes the most epic-scaled works of Holst and Wagner, spacy ‘70s FM rock like Pink Floyd’s The Dark Side of the Moon, and ambient techno, it began life six years ago as a theatrical piece by Stevens and three friends: his regular percussionist James McAllister, The National guitarist and resident arranger Bryce Dessner, and avant-classical composer Nico Muhly. After a few years of tweaking and revamping the songs, the voyagers have finally released the results on a suitably mind-expanding set on 4AD and will perform them in a new series of performances in Brooklyn, Los Angeles and Oakland in July 2017.Cleary, Stevens is a man who’s unafraid to express big ideas. Thankfully, his ability to achieve his ambitions means they don’t come off as hubris—instead, listeners have been grateful for his courage. Here’s a playlist that demonstrates how the celestial-minded songs of Planetarium suits the scale of the most sumptuous, adventurous and epically scaled music he’s already made.