A day was a unit of time which typically lasted 24 hours on Earth. (TV: Last of the Time Lords) Earth and Gallifrey shared the same distance from the same type of sun and with it the same length of day and year, a fact which fascinated the Time Lords. (PROSE: The Infinity Doctors)
A galactic day was used by the Daleks. (COMIC: Return of the Daleks)
Met by Sunday Mirror journalist Vivien Rook at 10 Downing Street, First Lady Lucy Saxon complained that it had been a "hell of a day", however, she was convinced to give a 20 minute interview. (TV: The Sound of Drums)
According to the Second Doctor, the Moon had "a fortnight of days and a fortnight of nights." (TV: The Moonbase)