What is the size of a planet, and has a small white hole as a moon ?
The Intergalactic Voyager One galaxy ship (IV-0001).
IV1 supports multiple life-form environments. The idea behind IV1 is that it is a representative of life in the Milky-Way galaxy. It’s purpose is to explore galaxies. It is an extension of the basic Star-Fleet philosophies to boldy go where no-one has gone before. Onboard the IV1 is a collection of species both intelligent and non-intelligent from all over the Milky-Way. The spacecraft, which is basically spherical in shape, is made up of a number of habitation zones. The surface varies from arctic and tropical desert to great forests of greenery. A substantial portion of the surface is liquid water for aquatic based life-forms. The IV1 was manufactured at planetary size specifically so that it could hold an atmosphere surrounding the vehicle. A planetary model was deemed the simplest, surest way to explore new galaxies. A spacecraft the size of a planet requires a substantial power-plant.
A miniature white hole nearby is used to power the galaxy craft. The galaxy craft represents the latest in technology from Star-Fleet. The white hole has several purposes, for one it acts a source of light during intergalactic travel. In theory the white-hole should never run out of power.
The galaxy ship is populated by explorers willing to travel to a new world. The galaxy ship appears on Star-Fleet star charts with no explanation as to what it is, it is simply labelled "IV1". If one wants to find out about it, one has to travel there. The consequence of that policy is that the IV0001 is populated primarily by explorers.