Thedion Four

Thedion Four was a planet with constant acid rain. The Doctor once had a picnic there while wearing a gas mask. The Twelfth Doctor mentioned this to Clara Oswald and was accused of lying by Maisie Pitt as, by that time, the planet had been destroyed for thousands of years. (TV: Mummy on the Orient Express)
Category:Planets
Category:Planets visited by the Doctor
Category:Fourth planets