The Suns of Caresh
Dagusa was a planet in Mutter’s Spiral. It was within a few dozen light-years of Earth.
The planet was the only one in Mutter’s Spiral that had a cinnamon-scented ocean. It had a nine-hour long day. Dagusa’s axis was tilted so far that its arctic circle was only two thousand miles from the equator.
The Third Doctor visited the planet to help calibrate the TARDIS navigational computer. Lady Solenti met him there to enlist his aid to save Caresh and the Realm of the Curia of Nineteen. (The Suns of Caresh)