Upon exploring a planet Dr. Rodney McKay discovers that the Stargate draws its energy from the atmosphere , and believes that this would be enough energy to power up a wormhole to Earth .
Upon exploring a planet Dr. Rodney McKay discovers that the Stargate draws its energy from the atmosphere ( the mist surrounding the planet ) . 
 He explains to the rest of his team that this would be enough energy to power up a wormhole to earth .