About to Kickoff Her Tour, Madonna Turns 57 and Pines for Penn

It's hard to believe, but Queen of Pop Madonna is turning 57 today. Is a romantic reunion with ex-husband Sean Penn what she will be wishing for when she blows out the candles?

Rumored to be celebrating today in the Hamptons, Madonna raised eyebrows by posting an image of herself with Penn on her Instagram in honor of their birthdays. The couple married in 1985 and divorced in 1989, but have been friendly in recent years, including traveling to Haiti on a mission of mercy together with Madonna's son by Guy Ritchie, Rocco.

In late July, a tabloid reported that Madonna and Penn were "back on" following his breakup with Charlize Theron.

Ironically, though Madonna has railed against leaks of her music and photo shoots, the image she used in her Instagram post is an unauthorized outtake from a 1986 session by famed photographer Herb Ritts, done for Interview magazine.

Madonna may want to wish for more discreet dancers if Penn proves out of reach; Yahoo! News published a piece yesterday claiming that her "Rebel Heart Tour" dancers were going "on strike" over low pay and her demanding ways. The tour kicks off September 9 in Montreal.

At least some of Madonna's classic hits will receive fresh airings on the tour. In honor of her birthday, check out her 10 biggest hits according to Billboard:

(10) "Open Your Heart" (1987)

(9) "Music" (2000)

(8) "Live to Tell" (1986)

(7) "Papa Don't Preach" (1986)

(6) "Like a Prayer" (1989)

(5) "Justify My Love" (1990)

(4) "Take a Bow" (1995)

(3) "Crazy for You" (1985)

(2) "Vogue" (1990)

(1) "Like a Virgin" (1984)