It was on this date in 1845 that H.L. Hencke discovered Astraea, the 5th known asteroid. The first asteroid, Ceres (now classified as a dwarf planet), was discovered in 1801. In the intervening years, 3 more discoveries followed: Pallas, Juno, and Vesta. Interestingly, at the time of its discovery, Astraea was classified as a planet, along with the other 4 objects now known to reside in the asteroid belt. However, with the advances in lens making that made the construction of far larger telescopes possible, the discovery of objects in the asteroid belt accelerated to the point where it became too cumbersome to classify these objects as planets. Result: by the end of the 1850s, these objects were known as asteroids (from the Greek for 'star-like') and, as more were discovered, the term 'asteroid belt' eventually came into use.