How does the Day/Night cycle work on the Elemental Plane of Fire?

So I found out, that there is a curfew every night in the City of Brass on the Elemental Plane of Fire. This makes me wonder: How does a day/night cycle work on the Elemental Plane of Fire? Is there a sun and if so, does it rise and set like a normal sun?

I’m looking for informations in any sourcebook of whatever edition of Dungeons & Dragons.