The moon will one day either break up into a planetary ring or hit Uranus.
Saturn is probably best known for the system of planetary rings that makes it visually unique.
Over the next weeks, she performed that operation eight more times, casting each of the planetary rings.
Saturn is best known for its planetary rings which are easy to see with a telescope.
The long arc of a planetary ring curved away into the stars.
They were, he supposed, like planetary rings that had been unwound.
Most planetary rings were only a kilometer or two thick, but I didn't want to take chances here.
There's still a lot we don't know about planetary rings.
"I'm afraid it's the price one must pay to learn about things such as moons and planetary rings."
This one was off-white, like a miniature planetary ring seen from a distance.
Wörterbuch für Astronomie