P2A-870 was a planet in the Milky Way galaxy, which held a Stargate and was in close proximity to P3W-451, relatively speaking. When Colonel Jack O'Neill and Colonel Frank Cromwell detonated a shaped charge into Earth's Stargate, in order to force the connection away from a black hole, the wormhole jumped from its connection at P3W-451 to P2A-870. With the wormhole no longer connected to a black hole, Captain Samantha Carter was able to finally shut it down. (SG1: "A Matter of Time")