Learn how to pronounce Saoirse Ronan’s name now (“sir-sha,” rhymes with “inertia”), because you’ll be seeing it plenty in the coming months. Born April 12, 1994, in rural Ireland, Ronan landed the three major roles every young actress her age was coveting, the leads in “Atonement,” “City of Ember” and “The Lovely Bones.”

“She’s a natural,” says director Joe Wright. “She seems to have some freakish acting gene that means she can just do it.”

Based on a taped audition, Ronan landed the key role in “Atonement,” 13-year-old Briony Tallis. The film studies her character at three points in her life — 13, 18 and 77 — and Wright was adamant about using separate actresses for each of the stages.

“I felt it was incredibly important that Briony was pubescent, if not pre-pubescent, that she was going through that horrific chemical change,” Wright says. “So unlike a lot of films in which they cast the older version with someone who’s a star, say, what we did was cast Saoirse first, and then we looked at older actors that could look like Saoirse.”

Among the role’s many challenges (though audiences would never guess it), Saoirse had to disguise her thick Irish brogue. “I’ve always had a good ear for accents,” says the young thesp, daughter of actor Paul Ronan. Trying to convey Briony’s inner thoughts was far trickier: “There are so many things going on in Briony’s head. I just thought of how frightened and confused she felt when she saw these things.”

“The amazing thing about Saoirse is that she acts from her imagination,” says Wright. “She’s never heard of Lee Strasberg. She isn’t involved in emotional recall. I like actors who work with their imagination rather than their own crap.”

“When I did ‘Atonement,’ I knew I want to do this for the rest of my life,” says Ronan, who’s now shooting “City of Ember” with Bill Murray in Belfast. “It’s kind of like a drug: Once you start, you can’t stop.”

Recent breakthrough: Major roles opposite Keira Knightley in “Atonement,” Catherine Zeta-Jones in “Death Defying Acts” and Michelle Pfeiffer in “I Could Never Be Your Woman.”

Role model: “I admire Keira. She gets a very hard time in the press because of her size and her shape, and she deals with it so well.”

What’s next: The lead in Peter Jackson’s “The Lovely Bones.”

“I really like Susie and I can’t wait to play her.”