292 POPULAR SCIENCE MONTHLY. 



eartli also in this furtlier respect that all tlie liglit it enjoys has 

 been derived from the sun. 



Though there is this immense difference between a star and a 

 planet, yet the observer must not expect to notice any such differ- 

 ence by merely taking a peep through the telescope. It was only 

 the long exposure in the photograph that revealed the little body. 

 Such is the manner in which an asteroid is generally discovered 

 in these latter days. A discovery like this comes as the well-earned 

 reward of the skill and patience of the astronomical photographer. 

 There are, indeed, a large number of known asteroids; our cata- 

 logues contained four hundred and thirty-two of them up to the 

 time when Witt exposed his now famous plate. Had the asteroid 

 Witt then found been merely as other asteroids, it would never have 

 received the prominent position that has now to be assigned to it in 

 any account of the astronomy of the century. That object foimd 

 by Witt on this night which is to be henceforth memorable in astron- 

 omy is of a wholly exceptional kind. Had Eros been merely an or- 

 dinary asteroid, Witt might no doubt have received the credit to 

 which his labors and success would have entitled him. Another as- 

 teroid would have been added to the long list of such objects already 

 known, but the newspapers would never have troubled their readers 

 about the matter, and the only persons who would have been 

 affected would have been the astronomers, and perhaps even among 

 them no particular sympathy would have been felt in certain quar- 

 ters. Those particular astronomers to whom has been intrusted 

 the special work of looking after the asteroids and of calculating 

 the tables of their movements might even have received with no 

 very great enthusiasm the announcement of this further addition to 

 the burden on their heavily laden shoulders. 



I have said that Eros is quite a small globe ; it may be well for 

 us fully to realize how small that asteroid actually is. If the moon 

 were to be crushed into two million equal fragments, each of those 

 parts would be as big as Eros. H the whole of Eros were to be 

 covered with houses, the city thus formed would not be so large 

 as greater London. So far as mere size is concerned, Eros is quite 

 unimportant. We can further illustrate this if we compare Eros 

 with some of the other planets. The well-known evening star, 

 Venus, the goddess of love, is a hundred million times as big as 

 that tiny orb we now call Eros, the god of love. After all this 

 it may seem strange to have to maintain what is, however, undoubt- 

 edly the fact, that the discovery of Eros is one of the most remark- 

 able discoveries of this century. 



Until Eros was discovered, our nearest neighbors among the 

 planets were considered to be Yenus on one side and Mars on the 



