Palnak's planet was a class M planet in a star system located within the Omega galaxy, in the galaxy's Alpha or Beta Quadrant.
Background
The planet was uninhabited in the 23rd century, only populated by a variety of birds and animal life, including an armadillo-like animal. Beginning in the 28th century, it featured a mammoth museum complex run by Palnak.
History
In 2265, the Federation starship USS Enterprise deployed a questing missile probe to explore the surface of Palnak's planet. Palnak became interested and used time travel to bring the probe, James T. Kirk and Spock into the future. When they vanished, Montgomery Scott brought rescue teams to the surface in
and a second shuttlecraft. Palnak also brought those people forward in time.
In the 28th century, Palnak's museum was built on the surface.
Over the next five centuries, Palnak brought various animal lifeforms to the planet, stored as exhibits in his museum.
In the 33rd century, Palnak attempted to preserve Kirk and Spock as exhibits, hoping also to preserve Scott's rescue teams. The crew were able to escape, with Spock operating the time-slip mechanism to transport them back to 2265. (TOS comic: "The Ageless One")