Giuseppe Piazzi (US: /ˈpjɑːtsi/ PYAHT-see, Italian: [dʒuˈzɛppe ˈpjattsi]; 16 July 1746 – 22 July 1826) was an Italian Catholic priest of the Theatine order, mathematician, and astronomer. He established an observatory at Palermo, now the Osservatorio Astronomico di Palermo – Giuseppe S. Vaiana. Perhaps his most famous discovery was the first dwarf planet, Ceres.