However, there is no way to return home, and they inadvertently awake a hostile alien race known as the Wraith, whose primary goal is to gather a fleet to invade Atlantis and find their new 'feeding ground', Earth. The first season is about a military-science expedition team discovering Atlantis and exploring the Pegasus Galaxy. The show also included new characters such as Teyla Emmagan and John Sheppard. Stargate Atlantis re-introduced supporting characters from the SG-1 universe, such as Elizabeth Weir and Rodney McKay among others. The show was a spin off of sister show, Stargate SG-1. The first season of the television series Stargate Atlantis commenced airing on the Sci Fi Channel in the United States on July 16, 2004, concluded on The Movie Network in Canada on January 31, 2005, and contained 20 episodes.
