Saturn’s Rings are Made of a Broken-Up Moon

Scientists have used computer modeling to determine that Saturn’s rings were created by the interactions of a now-destroyed moon with Titan.

IMAGE: The full set of rings, imaged as Saturn eclipsed the Sun from the vantage of the Cassini orbiter, 1.2 million km distant, on 19 July 2013 (brightness is exaggerated). Earth appears as a dot at 4 o’clock, between the G and E rings. CREDIT: NASA / JPL-Caltech / Space Science Institute

Ask almost any astronomer, professional or amateur, what got them interested in space and almost every one of them will have a story about the first time they looked through a telescope and saw Saturn. I still remember my first time, using a cheap, department store telescope my foster brother gave me. My father set it up in the backyard and pointed it at Saturn, and there were those rings. I was in awe, and it stuck with me. There is something about seeing Saturn’s rings with your own eyes through a tiny lens that brings out the astronomer in everyone. No matter the age of the audience, pointing a scope at Saturn is a surefire way to bring out the oohs and aahs at any star party.

Those rings are gorgeous. And while Saturn isn’t unique for having rings — Jupiter, Uranus, and Neptune all have ring systems — those rings are unique in that they can be seen with a basic telescope from Earth. To see the rings of the other giant planets, you need massive telescopes or spacecraft. Uranus’s rings were discovered in 1977, and since then, Voyager 2 and Hubble observations have led to the identification of thirteen distinct rings. Jupiter’s rings were first seen with Voyager back in 1979 and most recently imaged in the infrared with JWST. And while there were hints that Neptune had rings, they weren’t conclusively found until Voyager 2 swung by the ice giant back in 1989.

Obviously, ring systems are easy to acquire for giant planets, but the question still remains of how Saturn’s system is so much bigger and brighter than the other three systems. Saturn’s rings extend out from the planet’s equator starting 7,000 kilometers from the cloud layers and going all the way out to 80,000 kilometers. They are almost entirely made of water ice, which is another huge difference between the giant planets — Jupiter and Neptune’s rings are mostly dust.

IMAGE: This pair of Voyager 2 images (FDS 11446.21 and 11448.10), two 591-s exposures obtained through the clear filter of the wide angle camera, show the full ring system with the highest sensitivity. Visible in this figure are the bright, narrow N53 and N63 rings, the diffuse N42 ring, and (faintly) the plateau outside of the N53 ring (with its slight brightening near 57,500 km). The original NASA image has been cropped. CREDIT: NASA/Jet Propulsion Lab