2008 will mark the 60th anniversary of the dedication of the Hale Telescope (1948 - 2008). Over the course of the year I'll be presenting some historical highlights from the observatory's past.
January 1, 1801 —Long before the birth of the Palomar Observatory Ceres, the first asteroid, was discovered by Guiseppe Piazzi. For a time Ceres was thought to be a planet. With the discovery of other asteroids, and the asteroid belt, it was eventually realized that Ceres is better described as the largest member of the asteroid belt.
This same sort of sequence was repeated with Pluto. It was discovered in 1930 and classified as a planet. In the 1990s came the eventual discovery of the Kuiper Belt, a collection of icy bodies in the outer solar system. 2005 brought the discovery of distant Eris, a world larger than Pluto. Eris was discovered using the Palomar Observatory's Samuel Oschin Telescope. Its discovery called into question the planetary status of Pluto.
In 2006 Ceres, Pluto and Eris were re-classified and given a new status —dwarf planet. The International Astronomical Union (IAU) dropped down to just 8 planets.
Some people are still upset by the IAU's decision to demote Pluto. Others see it as just another step in our understanding of our back yard, the solar system.