PROGRESS OF MODERN ASTRONOMY 



The existence of the supernumerary was a puzzle, but 

 Olbers solved it for the moment by suggesting that 

 Ceres and Pallas, as he called his captive, might be 

 fragments of a quondam planet, shattered by internal 

 explosion or by the impact of a comet. Other sim- 

 ilar fragments, he ventured to predict, would be 

 found when searched for. William Herschel sanc- 

 tioned this theory, and suggested the name asteroids 

 for the tiny planets. The explosion theory was sup- 

 ported by the discovery of another asteroid, by Hard- 

 ing, of Lilienthal, in 1804, and it seemed clinched 

 when Olbers himself found a fourth in 1807. The 

 new-comers were named Juno and Vesta respec- 

 tively. 



There the case rested till 1845, when a Prussian 

 amateur astronomer named Hencke found another 

 asteroid, after long searching, and opened a new epoch 

 of discovery. From then on the finding of asteroids 

 became a commonplace. Latterly, with the aid of 

 photography, the list has been extended to above four 

 hundred, and as yet there seems no dearth in the sup- 

 ply, though doubtless all the larger members have been 

 revealed. Even these are but a few hundreds of miles 

 in diameter, while the smaller ones are too tiny for 

 measurement. The combined bulk of these minor 

 planets is believed to be but a fraction of that of the 

 h. 



Olbers's explosion theory, long accepted by astrono- 

 mers, has been proven open to fatal objections. The 

 minor planets are now believed to represent a ring of 

 cosmical matter, cast off from the solar nebula like the 

 rings that went to form the major planets, but prevent- 



