Center halos are areas of stellar mist where all dimensions converge, and time ceases to exist. They were theorized to exist by the Ancient called Delik, he believed that they were scattered throughout the universe. Though center halos were later proven to exist when encountered by the crew of Moya, they remain deeply mysterious.
Initially, upon the formation of a halo, time passes slowly. Eventually, however, the halo begins to harden. Once this process has completed, time stops altogether within it and anything inside of it remains trapped timelessly, until the halo opens into mist again. Navigation inside the mists of a center halo is difficult, with only 300 metras visible in any given direction. Escaping the mists without being stuck in a time loop or other time anomaly is difficult, and involves reversing out of the mist in exactly the spot a vessel has entered it. In one instance, this was accomplished through the nearly impossible reverse-starburst maneuver.
In at least one example, planets existed within a center halo. In these cases, the planets were unaffected by the halo although they could only be accessed when the halo softened into mist.
A center halo is featured in an episode of Farscape.