A planetary ring is a collection of small particles, ice, and dust that orbits a planet. These rings can vary in size and thickness, and they are often found around gas giants like Saturn, Jupiter, Uranus, and Neptune. The particles in the rings can range from tiny grains to large boulders. The formation of planetary rings is believed to occur when moons or comets get too close to a planet and are torn apart by its gravitational forces. This process creates a disk of debris that can remain in orbit for millions of years, contributing to the unique beauty of these celestial bodies.