“Music is a character in this film because a good portion of it is silent,” says director George Clooney about his movie “The Midnight Sky.” “Not just highlighting moments of sadness or terror, but also to carry the emotion all the way through.”

Composer Alexandre Desplat wrote more than 90 minutes of music for the sci-fi film, which stars Clooney as a scientist in the Arctic trying to contact a ship returning from Jupiter to convey the bad news: Radiation is enveloping Earth, and most of its inhabitants are dead or dying.

“It’s like a ballet or a concert on-screen,” notes Desplat. “The characters don’t talk much; the visuals are leading the story. Music conveys the emotions of all the characters: Augustine [Clooney], who is very ill; the little girl [Caoilinn Springall], who doesn’t speak; the crew in the spaceship.”

That girl, who turns up on the Arctic base when Augustine thought all his colleagues had departed, is the subject of one of Desplat’s two main themes. A delicate piano figure links her with the scientist. Another, more prominent, theme represents “survival and hope and heroism,” the composer says.

“My intent was for the film to be a meditation,” Clooney tells Variety. “Music had to be our language. Music was always going to be as big a character as any of the actors.”

While the story shifts between Clooney on Earth and the five-person crew on the ship millions of miles away, Desplat decided against musically differentiating the characters there. “Whether on Earth or in space, the music has the same tone, the same energy,” explains the two-time Oscar winner (“The Grand Budapest Hotel,” “The Shape of Water”).

The heart of the score was performed by a 50-piece string section from the London Symphony Orchestra, recorded at Abbey Road in early September. Desplat likens it to “the center of the solar system. In orbit around them we have a piano, some brass, some woodwinds and a ring of electronics, which blends with those sounds.”

Exactly how to treat the space scenes changed during the writing process, Desplat says. Clooney initially called for no music in space, “but when we tried, it seemed so bare it didn’t work.” For the astronauts’ first spacewalk, “very quiet, very slow strings play, as if suspended, motionless,” he says, “so it creates a kind of silence without being silent.”

The biggest challenge, Desplat reports, was in balancing the human aspects with the constant sense of danger, both on Earth and in space. “There’s a warmth between the characters, solidarity and friendship and benevolence. At the same time, you feel that nothing is safe. That balance was tricky to find.”

He and Clooney met via Zoom or Skype “every day or every other day” during the writing process in July and August. COVID-19 restrictions meant Desplat could not attend the London recording, but he watched from his Paris studio and was able to give notes to conductor Gavin Greenaway and the musicians during the sessions.

“The Midnight Sky” is Clooney’s sixth film as either director or producer with Desplat. Says Clooney: “He is my favorite composer in the world … not just a great composer but a great technician as well — as wonderful a collaborator as they come.”