The Erebus Supernova was a huge supernova that destroyed the original Valkyrie colony decades ago in the Polaris Galaxy. However, some Valkyries managed to survive and took residence on planet Vapedia. During the events of Ratchet & Clank Future: A Crack in Time, Nefarious agreed to help the Valkyries by using the Great Clock to prevent this if they helped him reach it. The Valkyries soon agreed, but the three Valkyrie leaders, Cassiopeia, Carina, and Libra were later destroyed; thus Nefarious betrayed the Valkyries. Without Cassiopeia, he no longer had any reason to help them, so nothing in the past was changed. According to Galactic Trivia, the Erebus supernova was the largest supernova in Polaris history.