Star Memory (星の記憶 Hoshi no Kioku) is a dimension where the memories of all Celestial Spirits are stored.
Star Memory is a dimension that greatly resembles outer space, appearing to have an infinite expanse, complete with many stars and asteroids; it exists separate from the Celestial Spirit World, and it is where the memories of all Celestial Spirits for generations are recorded and stored. The memories stored do not necessarily account for events that the Spirits physically saw, but also for events that took place within the proximity of their keys.
To enter Star Memory, a person must be invited by a Celestial Spirit, who engulfs them in a circle of light; upon being transported, it appears that the human being adopts a form similar to the Celestial Spirit that took them there, as Lucy Heartfilia and Brandish μ, upon being transported to Star Memory by Aquarius, adopted the form of a mermaid. To view the memories, someone must fly through Star Memory, where they will then enter a sort of tear in the fabric of the dimension that allows them to have an aerial view of the desired event. Aquarius equated the process of viewing memories from Star Memory as dreaming, however, every happening that is stored in Star Memory is the unequivocal truth. The existence of Star Memory allows for a Celestial Spirit to settle disputes over potential unrest involving their owner and someone else, and the memories they choose to show do not necessarily have to be their own.