The belt geometry is criss-crossing itself (exaggerated here for demonstration purposes):
To fix, delete and one side and re-extrude, this time being sure that it does not self-intersect.
- ↹ Tab into edit mode, ⌦ Delete
- E to extrude, then drag the mouse around. If the extrusion does not already appear to be locked along the object's local Z axis (there should be a line indicating this), press Z twice. Then press
1 to extrude exactly one blender unit (or whatever value you desire), precisely along the blue line.
Another alternative is to use the solidify modifier.
Also note that your clipping settings are causing lots of artifacts in the viewport. Generally you want to keep the clipping range as small as you can. I found
.1 . . .
1000 to work fairly well in this scene.