It was the first day of the first month of the first year of the new millennium, January 1, 1801. Giuseppe Piazzi, Sicilian astronomer, discovered a new planet which he named Ceres Ferdinandea, which most everybody else shortened to Ceres. Ceres was a Roman agricultural goddess, equivalent to the Greek Demeter. But she was also the patron goddess of Sicily. Ferdinand was the king of Sicily.
You can read a simple account of
how planet Ceres was discovered and later lost planet status.