Los Angeles, California (CNN) -- There's an innocence to Jessica Biel, she says.



The actress, who has starred in "The Illusionist" and "I Now Pronounce You Chuck and Larry," wanted to tap into her childlike side for "Planet 51," a new animated film about an Earth astronaut who lands on a faraway planet that has much in common with 1950s America -- except for the aliens.



"I love that kind of throwback to a more of innocent time and a simpler time and more conservative," she told CNN. "There's something just kind of attractive about that, those kinds of qualities to me, and I just thought it would be fun."



"Planet 51," which also features the voice work of Dwayne "The Rock" Johnson, Justin Long and Gary Oldman, opens Friday. Biel sat down with CNN to talk about the film, the challenges of voice work and the difficulty of finding good roles for actresses. The following is an edited version of the interview.



CNN: Why did you choose to do something animated?



Jessica Biel: I think I chose this part because I'm kind of a kid at heart and I really thought the story was so sweet and fun. ... I wasn't doing anything. I was able to work in town, at home in L.A., which is so rare.



CNN: You could probably wear your pajamas to work.



Biel: Pretty much. Roll in, no hair and makeup. I just always wanted to be a voice in some great movie where some little girl loves my character.



CNN: Did you get to meet [your co-stars] when you were doing the voices?



Biel: I never saw them, never met them. I mean, I know Dwayne, I've known Dwayne for a long time. I met Justin before, but I never saw them once. It was such an interesting experience to be there by yourself kind of going through it. But ... it goes fast. You're there, it's fast, it's fun.



CNN: Who's your character?



Biel: I play Neera, who is this lovely 16-year-old girl. ... She's insecure about boys but also has a sense of confidence for herself, very independent, and is not listening to what the government is saying about this alien [the Earthling] who's landed on her planet.



She is standing up on her own two feet, thinking for herself. ... So she's, you know, she's trying to find out who she is as a woman.



CNN: You do have a strong female character and it's such a good role model for young girls. Is it hard to find that in films today?



Biel: It is. It's very hard. I mean, honestly, it's just rare to find a story about a woman's experience, about a young girl's experience. For some reason nobody wants to make those movies.



And it's really hard because there are so many talented women and there are not enough projects for everybody to really blossom and explore. So it's quite competitive because there's a small amount of material.



CNN: Is it hard for Hollywood to write those kinds of roles?



Biel: I don't know what it is. I'm still trying to decipher that.
What film is Biel voicing? What did she want to reflect? What says Biel?
"Planet 51," childlike side "I love that kind of throwback to a more of innocent time and a simpler time and more conservative,"
question: What film is Biel voicing?, answer: "Planet 51," | question: What did she want to reflect?, answer: childlike side | question: What says Biel?, answer: "I love that kind of throwback to a more of innocent time and a simpler time and more conservative,"