P3X-474 is an uninhabited planet in the Milky Way Galaxy, but it does have a stargate. As SG-1 returned from Orilla aboard the Odyssey, they were pursued by Ori warships capable of tracking them through hyperspace. Unable to evade the warships, the Odyssey dropped out of hyperspace near P3X-474 and beamed the crew to the planet's surface so that they could safely return home by stargate. SG-1 and Landry intended to proceed in the Odyssey to preserve its new Asgard technology, but they came under attack once again and Carter was forced to activate a time dilation bubble to shield the ship from the Ori weapons. For 50 years, SG-1 remained trapped in time above P3X-474 until a way was found to reverse time and save the ship.
Episode Reference: Unending