World dangerously near the event horizon of a black hole, explored on a tragic mission by SG-10. Earth was nearly destroyed when the Stargate was connected to the planet and could not be shut down. But SG-1 later able to make use of their knowledge of the black hole to destroy much of Apophis's powerful fleet.
From the perspective of a normal space-time, it will be several years before the world is entirely enveloped by the anomaly.
HOME TO - Destroyed
FIRST APPEARED - A Matter of Time
A Matter of Time - Earth gates to P3W-451 to attempt to recover SG-10, but ends up shutting down Cheyenne Mountain in an attempt to avoid destruction from the gravitational pull of a black hole near the planet. SG-10 is lost in the line of duty.
Exodus - Hoping to annihilate Apophis's fleet of motherships with a supernova, SG-1 dials Vorash's Stargate to P3W-451 and sends the gate spiraling into the star system's sun.
2001 - P3W-451 is the first set of Stargate coordinates given to the Aschen when the S.G.C. perceives them to be an enemy threat.