(Reuters) - Some of music's most notable names including Billy Joel, Rihanna and Missy Elliott have signed an open letter to Pandora Media Inc opposing the online music company's push to change how artists are compensated. Pandora is currently lobbying lawmakers in U.S. Congress to pass the "Internet Radio Fairness Act," which would change regulation of how royalties are paid to artists. A group of 125 musicians who say they are fans of Pandora argue the bill would cut by 85 percent the amount of money an artist receives when his or her songs are played over the Internet. ...