 A total of 1,000 asteroids had been found by 1921, 10,000 by 1981, and 100,000 by 2000.Modern asteroid survey systems now use automated means to locate new minor planets in ever-increasing quantities.In 1802, shortly after discovering Pallas, Olbers suggested to Herschel that Ceres and Pallas were fragments of a much larger planet that once occupied the Mars–Jupiter region, this planet having suffered an internal explosion or a cometary impact many million years before (Odessan astronomer K. N. Savchenko suggested that Ceres, Pallas, Juno, and Vesta were escaped moons rather than fragments of the exploded planet).