In the center of the Materium is the sun, also sometimes referred to as the Brightflame or Lightgiver.

the planets, in order from inner to outer, are:

• Attiamel, a planet said to be in large part made of skymetals, as such a popular target for experimental exploration.
  
• Elud, the main inhabited planet and “centerpiece” of the Materium
• Iabanor, a slightly smaller planet that rotates around the sun at the same speed as Eludan and is always in its shadow.
  It is known to be inhabited. Though not confirmed the inhabitants are suspected to be Duergar and Drow, related to the Dwarves and Elves respectively.
  It is visible by eye in the sky of Eludan, though it is hard to spot as it is always in Eludan's shadow. {about half as big in the sky as the moon is to earth}
• Oweod, relatively little is know of this giant planet.
• Unor, relatively little is known of this about earth-sized wasteland.