Worlds of Creation: Asteroids

On January 1, 1801, the Italian astronomer Giuseppe Piazzi discovered a new ‘planet’ in between the orbits of Mars and Jupiter. What a great way to bring in the new year! Named Ceres, this new world was far smaller than the other seven planets (Neptune had not yet been discovered). Even the most powerful telescopes of the time could not discern any sizeable disk; the object resembled a star. Piazzi initially thought that Ceres might be a comet. The central nucleus of a comet indeed looks point-like in a telescope. But Ceres was not surrounded by a coma – a cloud that typically surrounds the nucleus of a comet. Nor did it have a tail. Further observations revealed a fairly circular orbit, typical of a planet but unlike any comet.