1801: The first asteroid is discovered by Italian astronomer Giuseppe Piazzi.

Piazzi, who christened it Ceres Ferdinandea (later shortened to Ceres when King Ferdinand IV fell out of favor, as monarchs have a tendency to do), at first thought he’d discovered a fixed star, but then detected it moving among the background of stars and decided it was a planet.

Playing it conservatively, the astronomer officially announced his discovery as a comet but confided his suspicions to another astronomer (no tail was visible, for one thing). Other observers eventually concluded that Piazzi’s discovery was indeed a planet, albeit a small one.

What he actually discovered was the largest asteroid in the belt between Mars and Jupiter. In fact, Ceres alone accounts for roughly one-third of the entire mass of the main asteroid belt. It has a diameter of approximately 600 miles and completes one revolution of the sun every 4.6 years.

In 2006, the International Astronomical Union voted to restore the planet designation to Ceres, decreeing that it qualifies as a dwarf planet. It does have some planet-like characteristics, including an interior that is separated into crust, mantle and core.

(Source: Various)