Ribos

Ribos was a planet located in the Skytha constellation. Ribos has an elliptical orbit around its sun, which means it has two seasons, each lasting around 32 years (Ice Time and Sun Time). There are traces of cadmium, bismuth, and iron in Ribos' crust. It has a native humanoid species called the Ribosians and a large predator known as the Shrivenzale.

Garron and Unstoffe attempted to sell the entire planet to Graff Vynda-K by leading him to believe that Jethrik was common on the planet. It was later visited by the Doctor, K-9 Mark II, and Romana I while in search of the Key to Time. (DW: The Ribos Operation)