Matt Smith’s replacement as the Tardis travelling Time Lord will be announced on August 4 in a live Doctor Who special on BBC America, the broadcaster said today. Hosted by Zoe Ball, the half hour Doctor Who Live: The Next Doctor will air at 11 AM PT and will be shown on BBC One in the UK simultaneously. The BBC says the actor taking over the role of the Twelfth Dr. Who will be interviewed on the show as will Smith, the show’s EP Steven Moffat, past Doctors and other guests. It was announced in early June that Smith would be leaving the role of the Eleventh Doctor after nearly four years. The actor will exit the show in the Dr. Who 50th anniversary special, set to air on November 23. The new Doctor will make his or her debut in the annual Christmas Special.