"Twinsun is a relatively new planet on the outskirts of a remote galaxy. Its rotational plane has stabilized between two suns. There is a huge mountain range running along its equator, that divides the planet in half: each hemisphere is warmed by a single sun. The Northern hemisphere, with its orange sky, is warmer than the Southern hemisphere. Except for a polar region, the planet's climate is clement. The formation of life forms on the planet was thus favourable."
Twinsun is rotating in the langrangian point between two different suns, hence the name, one over each pole. As a result, its equator is the coldest part of the planet, and its poles are the hottest. It is unknown if there is night on the planet. It is orbited by a moon.
It is revealed that the planet is hollow under its thick crust, and inhabited by the creature(s) collectively known as the "goddess Sendell". The planet's core serves for the gestation of a new entity.
It is suggested that Twinsun, as well as Zeelich, is much smaller than Earth and that the twinsunians are tiny creatures. In the Twinsunian Souvenir Shop there are captured gigantic artifacts such as paper clips and cotton buds found in space, obviously from Earth, and they are larger than a person.
As explained above, the planet is divided in two habitable hemispheres with the Well of Sendell being at the desert of the northern pole. When Dr. FunFrock ruled the planet, he ordered the Northen Hemisphere depopulated, and spread rumors of monsters and disasters to scare the people, in order to work around the Well and concentrate the building of his installations and forces there. The Southern Hemisphere therefore is the most populated, but some rogue groups persisted living in the Northern underground.
The dominant species of Twinsun are collectivelly known as "Twinsunians".
Twinsun has a variety of animals and other sentient or semi-sentient creatures. One wielding the Book of Bù can talk to many animals.