| 2003 | Timeline | 2005 |
Events
- Henry Hayes is elected President of the United States. He appoints Elizabeth Weir to head the SGC, while George Hammond becomes one of Hayes advisors. (SG1: "Inauguration")
- Battle of Antarctica: The Lost City of the Ancients is revealed to be Atlantis. The Antarctic outpost is crucial for Earth's salvation from the attack of the Goa'uld Anubis's fleet. (SG1: "Lost City")
- In an alternate reality, the battle results in the general public learning of the existence of the Goa'uld. In America, large numbers of people riot in panic or protest, and in response the government imposes martial law on the country. (SG1: "The Road Not Taken")
- Ba'al becomes the dominant System Lord. (SG1: "New Order")
- The Office of Homeworld Security is formed, under Hammond's authority. Jack O'Neill is promoted to Brigadier General and placed in charge of the SGC. Samantha Carter becomes CO of SG-1. (SG1: "New Order")
- The Atlantis Expedition is launched, under Dr. Weir's authority. (SGA: "Rising")
- The Wraith awaken from their hibernation cycle fifty years prematurely. (SGA: "Rising")
Production
Broadcasted episodes
- 9 January: SG1 "Evolution, Part 2"
- 16 January: SG1 "Grace"
- 23 January: SG1 "Fallout"
- 30 January: SG1 "Chimera"
- 6 February: SG1 "Death Knell"
- 13 February: SG1 "Heroes, Part 1"
- 20 February: SG1 "Heroes, Part 2"
- 27 February: SG1 "Resurrection"
- 5 March: SG1 "Inauguration"
- 12 March: SG1 "Lost City, Part 1"
- 19 March: SG1 "Lost City, Part 2"
- 9 July: SG1 "New Order"
- 16 July: ATL "Rising"
- 23 July: SG1 "Lockdown" and ATL "Hide and Seek"
- 30 July: SG1 "Zero Hour" and ATL "Thirty-Eight Minutes"
- 6 August: SG1 "Icon" and ATL "Suspicion"
- 13 August: SG1 "Avatar" and ATL "Childhood's End"
- 20 August: SG1 "Affinity" and ATL "Poisoning the Well"
- 27 August: SG1 "Covenant" and ATL "Underground"
- 10 September: SG1 "Sacrifices" and ATL "Home"
- 17 September: SG1 "Endgame" and ATL "The Storm"
- 8 November: ATL "The Eye"
- 15 November: ATL "The Defiant One"
- 22 November: ATL "Hot Zone"
- 29 November: ATL "Sanctuary"
- 6 December: ATL "Before I Sleep"
- 14 December: SG1 "Gemini"
- 21 December: SG1 "Prometheus Unbound"