Just a few days after unveiling the world premiere of the new trailer for Torchwood: Children of the Earth , the third season of the Doctor Who spin-off series, the digital cabler has announced an official launch date for the Russell T. Davies-scripted event series. BBC America will premiere Torchwood: Children of Earth on July 20th at 9 pm ET/PT. The third series, comprised of five serialized episodes, will air across five consecutive nights that week. The timing of Torchwood 's return to the schedule is linked to the launch of BBC America HD, a high-definition simulcast of the BBC America channel, which will also bow on July 20th to digital cabler subscribers. "BBC AMERICA is a truly unique channel in the cable landscape," said Garth Ancier, President of BBC Worldwide America in a statement. "We bring viewers some of the best programs on television and now with the option to experience them in HD, they’re going to be even better. The launch of BBC AMERICA HD coup