Who first described Saturn's rings as a flat disk around the planet?

Who first described Saturn's rings as a flat disk around the planet? Christiaan Huygens first described Saturn's rings as a flat disk around the planet.

Huygens used improved telescopes to study Saturn after Galileo's confusing observations of apparent side companions. In 1655, he proposed that Saturn was surrounded by a thin, solid-looking ring that was detached from the planet and inclined relative to Earth's line of sight. His explanation accounted for the ring's changing appearance as Saturn and Earth moved in their orbits.

Huygens published his discovery in Systema Saturnium in 1659, although he had announced the basic interpretation earlier. He also discovered Titan, Saturn's largest moon, in 1655. The ring was not literally a single solid disk: later observations showed a complex system of countless particles, mostly water ice, spread across many bands and gaps.

Galileo was the first to notice Saturn's unusual appearance in 1610, but his telescope could not reveal the ring's true form. Giovanni Domenico Cassini later found a prominent division within the rings, adding another major step to their scientific history.