The planet was built to be hollow, so an artificial center of gravity exists in the middle of the planet, a high density and very rare substance harvested from supernovas directly after they occur.
It has a hollow inside with a mechanical underworld run by machines which process and distribute packages across the galaxy. The interior of planet Callnowia is filled with a large, automated processing and distribution system for all kinds of shipping containers. The surface of Callnowia is covered in cannons and targeting arrays which are used to fire the goods to their destinations. When fired out into space the packages are concealed in asteroid-like heat shielding, and aside from a few operators and mechanics, the planet is completely mechanical.