P3X-972 is currently uninhabited. A crumbling castle on a cliff contained the meeting place and stored knowledge of the four advanced races of the Ancient Alliance: the Ancients, Asgard, Nox, and Furlings. Although P3X-972 is not on the Abydos cartouche, its coordinates are similar to those of Abydos, which allowed it to be dialed without compensating for planetary shift. It was the first destination of the stargate in 1945, when Ernest Littlefield was lost for over 50 years until SG-1's mission to search for him. Within the castle ruins, Ernest had discovered an alien device, intended as an archive of ancient knowledge, which he referred to as "Heliopolis." The planet also came to be called "Ernest's Planet," and was later designated PB2-908. During a violent storm, the castle, the ancient device, and the stargate were lost in the ocean, and the planet is no longer accessible.
Cross Reference: Ancient Alliance, Heliopolis, Catherine Langford, Ernest Littlefield
Episode Reference: The Torment of Tantalus