On January 1, 1801, a Sicilian astronomer named Giuseppe Piazzi discovered the dwarf planet Ceres orbiting the sun between Mars and Jupiter.
At the time, Ceres was considered to be a planet. But after astronomers found more things orbiting in the same region over the next few decades, they demoted Ceres and all those other objects to asteroid status. However, in 2006, the big debate about Pluto's planetary status led astronomers to redefine what it means to be a planet, and Ceres was reclassified as a dwarf planet along with. While it is the smallest of the known dwarf planets, it is the largest object in the asteroid belt.
