Meridian
A compound on Meridian in 2371
Meridian is a planet in the Gamma Quadrant's Trialus system that exists between dimensions and periodically shifts in and out of those dimensions. The planet is the homeworld of the Meridians.
The Trialus sun's core periodically builds to a cascade effect at the quantum level, causing Meridian to shift from one quantum reality to another. The planet appears in regular space every sixty years. When in the other dimension the planet's thirty inhabitants exist as pure consciousness and the planet and everything on it disappear from normal space. This has been the case for thousands of years.
By 2371, however, the planet had been undergoing changes for several centuries and its time in normal space had been growing shorter with each visit. At that time Meridian would manifest in normal space for only twelve days, and it was predicted that within a few centuries their stay would last only minutes.
That year, the USS Defiant, on a mission of exploration in the Gamma Quadrant, was present when Meridian returned to normal space for the first time since 2311. The crew of the starship studied the Trialus sun along with the scientists of Meridian and discovered an instability that was causing the shortened stay of the planet in normal space. With the help of the Defiant the Meridians were able to stabilize the star and expected their next manifestation to last 30 years, long enough to begin having families again. Jadzia Dax attempted to remain on Meridian as it shifted realities, but was unable to as her presence would have destroyed the planet. (DS9: "Meridian")