events of the film, Dr. Daniel Jackson deciphers the workings of the Stargate and a team is sent through to the planet on the other side. Stargate SG-1 resumes the story of the film, but establishes that Ra was one of many parasitic Goa'uld, aliens who identify as Earth deities to various primitive human communities on planets throughout the Milky Way. In its pilot episode "Children of the Gods", which takes place a year after the film, Stargate Command is established in response to an attack by the Goa'uld Apophis, and given the mandate to explore other worlds and obtain technologies that can be used to defend Earth. They encounter other races, such as the Asgard, who masquerade as Norse gods. Stargate SG-1 further extended the backstory of Earth humans by introducing the Ancients, an advanced race of humans from another galaxy who lived on Earth until approximately 10,000 years ago. Stargate device A Stargate is a device that allows practical, rapid travel between two distant locations. The first Stargate appears in the 1994 film Stargate, and subsequently carries over to Stargate SG-1 and its spin-offs. In these productions the Stargate functions as a plot generator, allowing the main characters to visit alien planets without the need for spaceships or any other fictional technology. Within the Stargate fictional universe, Stargates are large metal rings with nine "chevrons" spaced equally around their circumference. Pairs of Stargates function by generating an artificial stable wormhole between them, allowing one-way travel through. The symbols on the inner ring of the Stargate correspond to constellations and serve to map out coordinates for various destination planets and other locations in space. A typical Stargate measures in diameter, weighs , and is made of the fictional heavy mineral "naqahdah". The Stargates were created millions of years ago by an alien race known as the Ancients; their modern history begins when Egyptologist Daniel Jackson deciphers their workings in the Stargate film. The Stargate device sets apart SG-1 from other science fiction shows by allowing modern-day people to travel to other planets in an instant, although scholar Dave Hipple argued that SG-1 "also deploys [science fiction] stereotypes both to acknowledge forebears and to position itself as a deserving heir". With the help of the central Stargate device, the premise of Stargate SG-1 combines ancient cultures, present-day political and social concerns, aliens and advanced technologies. Near-instantaneous interplanetary travel allows a