Saturn was a gas giant, several million times larger than Earth. There were permanent depressions and lightning storms at both poles. Saturn had rings made of fragments of ice, which ranged in size from pebbles to ice the size of houses. The rings were made of a moon that was destroyed by the Arkive roughly around 50 million B.C. (PROSE: The Wheel of Ice)
Diamonds rained in Saturn's atmosphere, making the planet a popular site for mining. (PROSE: Diamond Dogs)
The Fifth Doctor and Nyssa visited Saturn in the future when there was a human colony on the planet; however, there was no explanation of how the atmosphere and surface were stabilised or how the gravity was regulated. The Doctor had heard of a utopian society on Saturn in the 47th century, but had never gotten round to visiting it before.
The utopian society had several interesting aspects. When citizens reached the age of one hundred years, they were forced to retire to Titan, where they ended up doing menial jobs and remotely operating all the public services and amenities on Saturn. Every automated system on Saturn, right down to the doors, was operated by thumbprint: these thumbprints automatically cut out when the owner reached one hundred. Robot servants were used on Saturn for jobs such as waiting on tables. Babies were created in vitro and delivered to their parents on Saturn when they reached the age of twenty years (therefore, there were no children nor teenagers on Saturn). Only people with satisfactory genetic stock were allowed to reproduce. (PROSE: Saturn)