306 



THE GUIDE TO NATURE 



rather that Mich stars as happen to be 

 travelling" most rapidly are most af- 

 fected by passing near to other bodies, 

 and are therefore must often converted 

 into nebulae. Apparently, from these 

 measures stars are changed into ne- 

 bulae rather than nebulae into stars. 

 But this view when confronted with 

 numerous other considerations ap- 

 pears to be less probable than the 

 other, and in fact there still remain 

 many difficulties and uncertainties in 

 either theory. 



Photographs of important nebulae 

 now being made at the Lick Obser- 

 vatory, when compared with those 

 taken some fifteen years ago, show 

 almost no appreciable change in these 

 mysterious bodies. Evidently, there- 

 fore, the nebulae must be very distant 

 — and if distant, of a size inconceiv- 

 ably vast. 



dred twenty-four miles away. If, then, 

 we let the point of a pencil represent 

 the earth, and the watch of some man 

 halfway across the room represents the 

 sun. Alpha Centauri, which is the near- 

 est star, will be another watch in De- 

 troit. 



ihe rest are still farther off — Chi- 

 cago, Galveston, San Francisco. Only 

 a few score of these star-watches would 

 be on the earth at all, while some 

 would be as far away as the moon. 

 Thick-strown, therefore, as are the 

 stars in the sky, they are by no means 

 exactly crowded. 



New Stars in Recent Years. 



It has been shown that the new stars 

 appearing in recent years, that is, stars 

 which suddenly shone out where pre- 

 viously no stars had been known to ex- 

 ist, have been converted into nebulae, 

 and later, in many cases into extremely 

 faint stars of apparently normal condi- 

 tion. As a consequence, the most prob- 

 able theory of new stars is that they 

 were originally so faint as not to have 

 been included in star catalogues ; that 

 they later passed through extensive 

 clouds of resisting materials, such that 

 the collisions on the star surfaces caused 

 sudden increase in brilliancy ; and, after 

 passing through tire resisting media, that 

 they reverted slowly to their original 

 state. — The Lick Observatory. 



Advantages of Reflecting Telescopes. 



The Crossley reflecting telescope es- 

 tablished for the first time the tremen- 

 dous advantage of this form of tele- 

 scope in the photography of certain 

 classes of celestial objects, such as neb- 

 ulae, star clusters, etc. To possess 

 reflecting telecopes became at once the 

 ambition of many observatories and 

 astronomers. Reflecting telescopes 

 more powerful than the Crossley are 

 now in use by, or under construction 

 for several of the leading observato- 

 ries. It is through the use of these in- 

 struments that some of the most strik- 

 ing advances of present day astronomy 

 are made. — The Lick Observatory. 



How Far Away are the Stars? 



When one looks up at the stars and 

 wonders how far away they are, let 

 him think of this : 



If the whole visible universe should 

 shrink down until the earth became 

 the size of one of the periods of this 

 page, one-seventieth of an inch across, 

 the moon would become a still smaller 

 dot, two-fifths of an inch away. The 

 sun, on the same scale, would be 

 twelve feet off and as large as the face 

 of a fair-sized watch, say an inch and 

 a half across. 



But the nearest fixed star, another 

 watch face for size, would be six hun- 



Astronomical Interest. 



James Lick's gift of a great telescope 

 and observatory announced in 1874, and 

 the frequent reports of progress made 

 by the builders, created widespread in- 

 terest in astronomy, especially in Cali- 

 fornia. The many observatories, pub- 

 lic and private, established in California 

 in following years, owed their inception 

 chiefly to this interest. — The Lick Ob- 

 servatory. 



The familiar theory that sun spots 

 are vast tornadoes in the solar atmos- 

 phere is farther corroborated by a re- 

 cent discovery of G. E. Hale's that 

 similar sun-storms on opposite sides 

 of the equator rotate in opposite di- 

 rections, precisely like the cyclones, 

 tornadoes and hurricanes of the earth. 



The Lick Observatory reports the 

 discovery of a new, and ninth, satel- 

 lite of Jupiter. The motion is retro- 

 grade and the period about three 

 vears. 



