AP file photo Miley Cyrus and her father, Billy Ray Cyrus, sing a duet, "Ready, Set, Go" during the CMT Music Awards last month in Nashville, Tenn.

NEW YORK — "You get the best of both worlds," Miley Cyrus sings in the theme song of her hugely popular Disney Channel show, "Hannah Montana." It's a reference to her character's secret double life as both a rock star and a normal schoolgirl.

Off-screen, though, this 15-year-old phenom is starting to learn how hard it really is to have the best of both worlds: as a G-rated Disney superstar and a real-life, growing teenager with an eye on a long career.

Cyrus, whose fresh, easy charm and down-home Southern appeal have catapulted her to an astonishing level of celebrity, especially in the past year, found herself having to apologize April 27 for some entirely un-Miley photos in Vanity Fair magazine.

At a moment when she otherwise would have been relishing an amazing week — a deal for her memoirs (reportedly seven figures), the cover of People magazine and a feature in Vanity Fair — she issued a statement saying how embarrassed she was. This came almost certainly at the behest of worried executives at The Walt Disney Co., for whom she will reap a reported $1 billion this year.

For the record, only Cyrus' back and shoulders are bare in the most controversial shot by Annie Leibovitz, the renowned celebrity photographer. Many an Oscar-night gown would show as much skin.

But Cyrus is 15, with a fan base that begins in preschool. And it's what the photo suggests rather than shows — the idea that she might be nude, perhaps even in bed — that bothered some parents who poured their feelings onto blogs. She wasn't nude during the shoot, nor in bed, but she does have a subtle come-hither expression.

Leibovitz said Monday that she and Cyrus had discussed the photos beforehand, and Vanity Fair said "Miley's parents and/or minders were on the set all day ... everyone thought it was a beautiful and natural portrait." As for Disney, it accused editors of creating a situation "to deliberately manipulate a 15-year-old."

Coincidental bad timing

Unfortunately for Cyrus, the photos, taken in February, might not have made nearly such a splash but for a bit of awkward timing: They emerged just days after a handful of borderline racy snapshots of a girl who appeared to be Cyrus appeared on the Internet.

So the timing was terrible. But some celebrity watchers saw the developments as an attempt by Cyrus and her handlers — while not necessarily calculated — to look ahead a few years, beyond the tween audience.

"She has to find a way to gain a new following," said Peter Castro, deputy managing editor of People magazine.

Cyrus' predicament evoked plenty of references to the cautionary tale of Britney Spears, who started on the Disney Channel about the same age as Cyrus and had her first huge hit, "Baby One More Time," at age 17.

"Britney was in a Miley place," said Castro. Then she decided to break out, making her persona in "Baby One More Time" a sexy schoolgirl, and doing a provocative photo shoot for Rolling Stone. "She alienated parents, but gained a whole following of older kids," he said.

But, he added, "I don't know that Miley could get away with that. I think her dad and management team are closely following Britney's career, saying, Don't let this ever happen to you.'"

Unlike the 26-year-old Britney of today, the self-possessed and upbeat Cyrus has worn the title of "role model" easily. She has been utterly scandal-free until now, unless you count her failure to wear a seat belt during a car ride in her concert movie (her dad apologized for that, too).

"Miley's at the very top of our celebrity list," said Joanna Saltz, executive editor of Seventeen magazine, whose average reader is about 16. While Spears never appears in Seventeen, readers love Cyrus, Saltz said, because she seems genuine, unproduced, comfortable in her own skin.

"And she's just exploded," said Saltz. "A year ago she was the queen of tweens, and now she's a favorite of our readers. She's crossed all age groups."

An economic juggernaut

Just how big is this young lady, whose 70-date concert tour in 2007 sold out within minutes, who had desperate parents filing lawsuits and entering wacky endurance contests (like hanging onto a pole for six days) to get tickets, who herself took home $1 million a week and something close to $20 million from the tour?

"Honestly, it's astounding," said Rolling Stone editor Andy Greene. "She was selling 20,000-seat houses. She could have sold 80,000 a night. I spoke to one dad who said the atmosphere in there was like nothing since the early Beatles concerts. It's hard to think of anything quite like this."

"Hannah Montana" is the No. 1 cable series for kids aged 6-14, and if you include the networks, second only to "American Idol." And even Cyrus' consolation prize to fans who couldn't get concert tickets, the "Best of Both Worlds Concert" 3-D movie, grossed more than $60 million, a rare hit for a concert film.

Her two soundtrack albums have sold 3.5 million and 3 million copies respectively in this country, according to Nielsen SoundScan. And according to People, "Hannah Montana" merchandise — from bedding to handbags to toys to shoes — is expected to rake in $1 billion this fiscal year.

Ultimately, whether Cyrus' career will be hurt by these photos will come down to parents — after all, many tweens won't even see them.

Certainly Seventeen magazine will be staying on her side.

"What happened this weekend is part of what makes her such a great role model," said Saltz, the editor. "When she thinks she's made a mistake, she immediately owns up to it. She doesn't run from it or deny it. That's very rare to see in young celebrities today."