In the spring of 2012, at the Barbican Hall in London, Sufjan Stevens, Nico Muhly and Bryce Dessner performed a new collaborative work they named Planetarium. A song cycle loosely in homage to the solar system, it wanted for little in ambition, featuring seven trombones, a string quartet, guitar, voices, piano, celeste, and an elaborate lighting display that cast a succession of colours against a giant suspended orb.



Some way into the evening, however, the giant orb slowly began to deflate. “That was our Spinal Tap moment,” recalls Muhly now, mock-sorrow barely suppressing the glee of a good story. “One of my friends came up to me afterwards and said, ‘It was rather like a saggy testicle, wasn’t it?’”

Five years later, on a hot day in Manhattan, Muhly, Stevens and Dessner are assembled in the offices of their record label, 4AD, recalling the fate of the orb (retired upstate), their long-standing collaborative relationship, and the prodigious task of recording the whole fandango for an album version of Planetarium.

They are three of the most distinctive musical minds of their generation. Today, though, they are in playful mood, lined up before me, a curious amalgamation of the three wise monkeys and a well-synchronised boyband. Muhly, a composer who has worked with Philip Glass, Björk and the ENO, and scored the Oscar-winning film The Reader, speaks at a whip-smart canter; Stevens, one of America’s most revered songwriters, sits in the middle, buried beneath a baseball cap; Dessner, best known for his work as guitarist for the National, though also a classical composer working with the likes of Steve Reich, Jonny Greenwood and the Los Angeles Philharmonic, keeps a quiet, watchful eye over proceedings.

The three met 15 years ago, when sharing the same Brooklyn neighbourhood, and what began as mutual musical admiration soon grew into collaboration. “Both have made very significant contributions to National albums over the years,” explains Dessner. “Nico’s commissioned me; I’ve commissioned him several times. And he often looks at my scores before I submit them to other people, and saves me embarrassment.” Muhly can be brutal. “He’s friendly-brutal,” Dessner smiles. “In fact I can often request the level of brutality.”

Planetarium began when Muhly, then composer in residence at Muziekgebouw Eindhoven in the Netherlands, was approached by the venue’s musical director about making a large collaborative piece. “He said ‘Who would you want to work with if you had carte blanche?’ and I said ‘these two’.”

The three discussed the idea at length. “And it got bigger and bigger and bigger until it turned into this ‘Let’s make this giant, evening-long thing!’” he recalls. Why exactly did they choose space as their subject matter? “Because that is the whole world,” jabbers Muhly. “We covered it all!”

“Sufjan was the one who wanted to do space,” Dessner interjects patiently, and then Stevens suddenly speaks, adopting a continuity announcer’s booming gravitas: “Since the dawn of time, mankind has looked towards the heavens in search of meaning …” Then he collapses into giggles.

‘We covered it all!’ … Muhly, Stevens and Dessner. Photograph: Tim Knox/The Guardian

“But then what made the thing make sense was you researched, you got down to the bottom of the space hole,” Muhly says to Stevens. “Plus,” adds Dessner, “he had stacks of books about space on his bedside table for months.” Stevens looks faintly embarrassed. “It’s actually not that scholastic at all,” he says. “I just take every fourth word from Wikipedia and hope that it rhymes.”

The result is a striking collision of their three musical personalities. On some tracks,such as Pluto, a song Stevens began on guitar 20 years ago and never used, their styles converge and meld. On others, such as Mars, the parts feel quite distinct; the synth and vocal beginnings are Stevens, the combustive trombone section belongs to Muhly, and the intricate guitar ending is pure Dessner.

The recording was finished last November, in upstate New York, in the days around the US election, and though the lyrics remained the same as they had been five years earlier, the themes of chaos, uncertainty and the threat of war had acquired a new weight and timeliness.

“I was borrowing from Greek and Roman mythology and astrology, and there’s one Easter myth in there,” says Stevens. “These are stories that have these universal themes: what does it mean to be human? What is our relationship towards the environment, and towards society? What are your human rights? And in the polytheistic world of the ancient Greeks and Romans it’s just a total mess, there isn’t a clear and coherent organisation of what is good and what is bad, what is truth and what is fiction. It’s very ambiguous.”

Stevens claims he is “not entirely proud of the album’s lyrics. I’m obsessed with sound and melody and texture and all these things distract me and excite me more than the words do. Sometimes I’ll find a word or a phrase that I love – like ‘messenger-dwarfism’ – and I don’t know what it means, but it sort of relates to Pluto being a dwarf planet. Or I’ll think about the mythological vernacular, something can grow out of a word like ‘callipygian’. It’s one of my favourite words on the record.” Why? “Well, because it means finely shaped buttocks!” He laughs broadly.

Each saw one another’s contributions as fair game, all working in service to the music. “It wasn’t about censoring anyone,” says Dessner, “it was about encouraging them to do better.” The others laugh. “There was a lot of abuse,” Muhly admits. “I can be very, very mean and critical and disparaging.” The worst moment came before the premiere in Eindhoven. “We were coming home to the hotel and Sufjan decided he didn’t like the middle section of Mars and asked Nico to rewrite it,” Dessner recalls. “It was very specific. He said: ‘Can you redo the middle section of this and make it sound really Ligeti-y?’”

‘A document of friendship’ … Dessner, Muhly and Stevens. Photograph: Tim Knox/The Guardian

They also had to address Stevens’ penchant for abrasive synths. “We would have this elaborate, beautiful thing …” begins Dessner, wistfully.

“Like interlocking patterns …” Muhly continues. “And then you would come in like FFFFFFSCHHHHKWAAAGHHH,” he makes an aggressive squelching sound in Stevens’ direction.

“I would say: ‘You are the least subtle musician ever!’” Dessner says. “People think he’s this beautiful folk musician, he’s actually just this aggressive avant-garde Tempest player. But there are frequencies in there that please you, which is similar to Nico’s love of the bass trombone …”

The three can regale you with tales of their musical friendship, which might carry a more bawdy, lads-on-tour quality, were they not to include memories of “Brucknerian harmony”, attending evensong together and the night that began with Stevens turning pages for Muhly’s performance at Westminster Abbey and ended when Muhly “went on the treadmill drunk” in Stevens’ hotel room.

It’s an insight into how they interlace themselves, musically and as friends. For Dessner, who now lives in Paris, recording this record was a way to strike up that long-running conversation with his friends in New York once more. “For me, these songs have taken on a new meaning,” he says, “which is less about how I want to sell records, and more about having an important document of our friendship.”

• Planetarium is out now on 4AD.