Ceres was discovered by the Italian priest Giuseppe Piazzi (1746–1826) on January 1, 1801. Piazzi observed a starlike body that was not listed in the star catalogues of the time. He observed the object over several nights and noted that it moved relative to the fixed stellar background, faster than Jupiter but slower than Mars. Piazzi deduced that this object was a new planet, orbiting between Mars and Jupiter. He named the planet Ceres, after the Roman goddess of agriculture. The German mathematician Karl Friedrich Gauss (1777–1855) confirmed Ceres’s orbit later that year.

Ceres was considered a planet for several decades, until so many small planets were found orbiting between Mars and Jupiter that astronomers felt that further classification was necessary. Hence, Ceres went from being the smallest planet to the first asteroid ever discovered. Ceres is still the largest asteroid known. Recently, at the same time Pluto’s status was adjusted, Ceres’s was also adjusted; now, Ceres is considered a dwarf planet as well as the largest asteroid.