SIRIUS, a satellite radio provider that delivers commercial-free music and sports programming to cars and homes across the country, announced on July 14 that it passed the 500,000-subscriber mark. The company expects to have 1 million subscribers by the end of the year. At the close of business on July 13, SIRIUS had 500,749 subscribers to its nationwide service of 65 music channels and more than 50 channels of news, weather, traffic, entertainment and sports.