Giuseppe Piazzi discovers Ceres, the first asteroid

Background. In 1772, Johann Elert Bode, citing Johann Daniel Titius, published a formula later known as the Titius-Bode law that appeared to predict the orbits of the known planets but left an unexplained gap between Mars and Jupiter. In 1800, Franz Xaver von Zach, editor of the Monatliche Correspondenz, sent requests to twenty-four experienced astronomers he dubbed the "celestial police", asking them to search methodically for the expected planet. Piazzi discovered the object before receiving his invitation to join this group.

Observation and Announcement. Piazzi observed the moving object twenty-four times, with the final sighting on 11 February 1801, when illness interrupted his work. He announced the discovery on 24 January 1801 in letters to fellow astronomers Barnaba Oriani and Johann Elert Bode. The information was published in the September 1801 issue of the Monthly Correspondence.

Classification and Naming. Piazzi named the object Cerere Ferdinandea, honoring the myth of Ceres in Sicily and King Ferdinand. It was initially announced as a new planet. Later, it was classified as an asteroid, and more recently as a dwarf planet. The term 'asteroid' was introduced by Herschel in 1802 after the discovery of Pallas.