The sun will set on the Oprah Winfrey Show – on of America’s most popular TV shows – in September 2011 after two decades on the airwaves. “Billionaire Ms Winfrey, 55, one of the most influential women in the US, has hosted the show since 1986. A spokesman for the star's Harpo production company would not say why Winfrey had decided to quit, but said she would discuss it on Friday's show. Winfrey is expected to focus instead on the launch of her own TV channel. She already runs a satellite radio station, Oprah Radio, with presenters including Dr Maya Angelou and sex therapist Dr Laura Berman. The Oprah Winfrey Show, currently syndicated in 145 countries, has transformed the star into a cultural phenomenon. The show's open atmosphere and frank conversation redefined the talk show genre and made Winfrey the wealthiest black woman in the world.”