Unsung Little Worlds

Abstract

On the night of January 1, 1801, astronomer Giuseppe Piazzi was conducting a stellar survey for what would become the great Palermo Star Catalogue of some 7600 stars, when he noted the presence of something unusual. One of the apparent stars was moving! His initial thought was that he had found a new comet, however if this was a comet, it was a strange one as it appeared consistently starlike and, during the following days and weeks, revealed no tendency toward developing a fuzzy coma and tail. Moreover, the orbit that was eventually calculated for this body was unlike anything ever computed for a comet. The orbit was that of a planet, lying neatly within the broad and apparently empty region between Mars and Jupiter.