Gregory Peck's grandson plays a young George Clooney in The Midnight Sky

George Clooney cast Ethan Peck, Gregory Peck's grandson, as a younger version of his character in The Midnight Sky, after passing up a high-tech de-ageing tool to play the role himself.

Speaking to Deadline, Clooney, who both directed and stars in the Netflix sci-fi film, shared that although he considered using the special technology that made Robert De Niro appear younger in The Irishman, he decided doing so would cause too much fuss.

"The Irishman used it and had not come out yet," Clooney recounted.

"(Producers) showed it to me and I thought, 'That'll just become a topic then that people will talk about'. I didn't know how people would react to it at the time," he rationalised, admitting: "It's tricky because people know basically what I looked like when I was 35 years old."

Clooney then said he cast Peck in the part because both men "have good eyebrows".

"He's better looking than me and if I'm going to cast somebody why not f**king cast somebody who's better looking than me," Clooney mused.

Matching the pitch of both actor's voices to give the impression they were the same person also proved to be a challenge, Clooney shared.

"I said to (Peck), 'Look, my voice is pretty recognisable, so we're going to have to work together, you and I, and we're going to... work with everybody on blending your voice with mine'."

Clooney praised Peck's performance in The Midnight Sky, extolling: "He gives such a beautiful performance because he's playing my character at an unlikeable time. The reason that he needs redemption is because of that. So it's a really brave thing he did, which is he came onboard and said, 'Yeah, let's do it. I'm up for it'."
The Midnight Sky hits Netflix on December 23.