A doomed giant moon losing its outer crust likely led to the creation of Saturn's rings, a planetary scientist proposed Monday.

At the ongoing Division for Planetary Science of the American Astronomical Society meeting in Pasadena, Calif., Robin Canup of the Southwest Research Institute looked at the mysterious origins of Saturn's rings. The rings are more than 90% water-ice, but smash-ups between moons -- the conventional explanation for the glittering arcs surrounding Saturn -- would have created a mixture of ice and rock, instead of their current composition, he notes.

Instead Canup suggests that a moon the size of Titan, Saturn's only large satellite at about 3,200 miles in diameter, may have shattered and swirled into the ringed planet, leaving the ring behind. Before breaking up, gravitational tides would have stripped the icy outer core of the moon from its surface, "leading to the production of a massive, pure ice ring," Canup says in the meeting's program.

The rocky inner core of the moon ended up cannon-balling straight into Saturn, leaving behind a thick ring of ice, Canup proposes. "Over time the ring viscously spreads, its mass decreases, and icy moons are spawned from its outer edge."

"Awesome," said Caltech astronomer Mike Brown, by Twitter, anointing the presentation his favorite meeting talk of the day.

By Dan Vergano