2o8 



THE GUIDE TO NATURE 



Figure 3. The ol)server will at the pre- 

 sent time see several spots upon its 

 surface, and if he will look at these at 

 intervals of a few days he will plainly 

 see that our great luminary is steadily 

 turning around upon it axis, just as the 

 earth is doing. But our great sun, a 

 million times larger than our earth, in- 

 stead of turning about once each day. 



Fig. 3. The a|iptavancc ut tlu Mm a^ viewed in a 

 small telescope. 



occupies twenty-five and one-third days 

 in making one single rotation. If, there- 

 fore, the observer sees a large spot just 

 coming around the advancing edge — 

 that is, just rising to his view — nearly 

 two weeks will elapse before its steady 

 onward motion will have carried it en- 

 tirely across the disc of the sun and 

 caused it to withdraw from view to 

 the side of the sun which is ever hid- 

 den from us. 



Our svm is an inconceivably large 

 body, no less than 866,500 miles in di- 

 ameter, and it is so excessively hot that 

 the temperature, even of its cooler out- 

 er layer, is no less than 12,000 degrees 

 above zero. This is sufficient not only 

 to melt but to instantly vaporize any 

 known substance which occurs upon 

 the earth. Consequently we believe 

 that the sun is nothing but a great ball 

 of intensely heated, gaseous matter. 

 How inconceivably hot its interior may 

 be we have no means of ascertaining, 

 but doubtless great currents o'f super- 

 heated matter are forever rushing from 

 the interior to the surface and, becom- 

 ing cooled there, are sinking to the in- 

 terior again — currents of vaporized 

 metals and other substances on which 

 whole earths like ours would be carried 

 as easily as small chips are carried up- 

 on the surface of a swiftly flowing mill 

 stream. 



The whole enormous ball is in a 

 state of inconceivably violent agitation. 

 It is no wonder that great disturbances 

 appear upon its surface, known to us 

 as sun spots, and that these are some- 

 times of forty or even fifty thousand 

 miles in diameter. We do not know 

 their exact nature, nor do we know 

 why, every 11 years, they reappear in 

 very unusual numbers. But long-con- 

 tinued observations have shown that 

 the inconceivably violent agitations to 

 which this great ball is subjected at- 

 tain their maximum regularly at times 

 separated by this constant interval. It 

 is certain that these disturbances will 

 thus be the greatest from toward the 

 end of the present year until nearly the 

 middle of 1916. It is during these 

 months that our sun will be an object 

 of the highest interest for study to 

 those who are so fortunate as to have 

 access to a small telescope. 



The Planets in November. 



Mercury, which passed to the west of 

 the sun and became a morning star on 

 October 22, will reach its greatest wes- 

 tern elongation on November 7, and at 

 this time may be seen in the early dawn 

 for nearly two hours before sunrise. 

 It must be looked for very near the 

 ground, a little south of the east point, 

 where it will be seen shining with three 

 times the brightness of a standard first- 

 magnitude star. In the telescope dur- 

 ing the last days of October it will ap- 

 i:)ear as a beautiful, thin, silvery cres- 

 cent, becoming half full on November 

 7, and from then on rapidly increasing 

 its phase. 



Venus is destined soon to be the 

 most conspicuous object of the evening 

 skies, but it is still too near the sun to 

 be easily observed. On November i it 

 sets but 50 minutes after svmset, and 

 this time is increased to only i hour 

 and 10 minutes by November 30. The 

 planet is now moving very rapidly 

 southward over the sky and by the lat- 

 ter date is almost 25 degrees below the 

 equator. Soon after the end of the 

 month, however, it will begin to move 

 rapidly northward and will thus soon 

 be seen high in the evening sky. At 

 present it must be looked for far south 

 of the west point of the horizon, shin- 

 ing in the twilight for about an hour 

 after the sun has set. 



