The big ring is a Banks Orbital, a smaller cousin of a Ringworld. It has a diameter of 3.6 million kilometers, at a distance of 12.5 million kilometers from earth. It fills the sky. The smaller ring, between the Moon and the big ring, is the same Banks Orbital at a distance of 150 million kilometers.

The width of the Orbital’s ring is 50000 kilometers in both cases.

Photo “Full Moon” by Gibsongolfer, cc-by-sa licensed. (The above graphic is therefore under the same license.)