>Is there a ring around Sedna?
Too little is known about this far-off asteroids - err, "dwarf planets". But the answer is probably "no", there is probably no ring around Pluto, Sedna, or Xena.
The 8 "remaining" planets are in two general categories.
First, there are the "giant planets" - Jupiter, Saturn, Uranus, Neptune (mentioned in order of size - which also happens to be the order in the Solar System). These have diamaters between 5 (?) and 11 times the diameter of the Earth.
All of them have rings. They also have many moons. These two facts are probably related - in fact, the rings can be considered a collection of an inmense amount of mini-moons of all sizes, from a few meters down to specks of dust.
Then, there are the terrestrial planets - Earth, Venus, Mars, Mercury (again, mentioned in order of size). These do not have rings, and only few moons (Earth 1, Mars 2, Venus and Mercury none).
I guess the large gravitational attraction of the giants are related to the presence of rings.
Difference in opinions hath cost many millions of lives: for instance, whether flesh be bread, or bread be flesh; whether whistling be a vice or a virtue; whether it be better to kiss a post, or throw it into the fire... (from Gulliver's Travels)
