We have a ship. One that runs on the Light that we were tryin' to find. It's this whole thing, where the Light landed on our world and with it, we built the ship. We meant to go out and just explore some neighboring planets, but when our world got destroyed, we just kinda got stuck in this cycle of planet hopping.

They're all part of the same planar-universe, but lotsa different realities and such. Not really defined by time. The ship takes us wherever it wants to go.