Many are familiar with the "planet" versus "spheret" point being made by flat earthers.
What hasn't been mentioned is the suffix "et" which means small, diminutive in Latin, Greek, Roman, etc. (Think "cigar" and "cigarette").
So planet is flat, but small. This supports the theory that our domain is just a small portion of a much larger plain.
Other "planets" are on the same plane we are. Their sun's (luminaries) are visible to us as reflections on our firmament, much like your neighbor's front porch light shines a reflection on your window.