26o 



THE GUIDE TO NATURE 



times as bright as the Pole Star. As to 

 the cause of this wonderful periodic dis- 

 turbance in this distant sun, we are as 

 yet in complete ignorance. 



The Partial Eclipse of the Moon. 



The interesting- eclipse of January 20 

 unfortunately occurs at so late an hour 

 of the night that it will probably only be 

 seen by those of us who are so interested 

 in astronomy that they will make a spe- 



Figure 3. The partial eclipse of the moon on the 

 morning of January 20th. 



cial effort to observe it. The eclipse is 

 also a very partial one, only about one- 

 seventh of the moon's diameter being cov- 

 ered by the shadow. 



The great shadow of the earth, \vhich 

 always stretches out into space in a direc- 

 tion exactly away from the sun, has the 

 form of a great cone whose base is the 

 earth and whose length is no less than 

 857,000 miles in diameter. 



Figure 3 shows this portion of the 

 shadow, and also the motion of the full 

 moon as we will view it on the morning 

 of January 20. Our satellite will reach 

 the position A' and the eclipse begin at 2 

 hrs. 55 min. A.M., (Eastern Standard 

 Time) ; it will reach B and the eclipse will 

 be the greatest, at 3 hrs. 39 min. A.M., 

 and it will finally reach C and the eclipse 

 terminate at 4 hrs. 24 min. A.M. 



The entire phenomenon will thus last 

 I hr. 29 min. ; but it will be noticed that 

 even when the eclipse is greatest it will 

 only be a small portion of the lower edge 

 of our satellite which is hidden from us. 

 Throughout the eclipse the moon will be 

 seen high in the sky, in the beginning it 



will be about three hours past the merid- 

 ian, and at the end it will be about one- 

 third the way up from the northwestern 

 horizon to the zenith. 



The Planets in January. 



Alercury will attain its greatest distance 

 east of the sun on January 20 and for a 

 few evenings before and after this date 

 it may be seen shining brightly in the twi- 

 light glow, low in the southwest for a 

 short time after sunset. It will pass to 

 the west of the sun and become a morn- 

 ing star on February 5. 



The observer may have noticed how 

 very brilliantly the beautiful planet Venus 

 has been shining in the southwest, just 

 after sunset. For many weeks past, and 

 also throughout the present month, it con- 

 tinually moves northward among the 

 stars, and is therefore seen continually 

 creeping from the south to the west point 

 of the horizon. On January I, it sets in 

 the southwest about two hours after stui- 

 set ; by January 31, this time is increased 

 to two and one-half hours, and the planet 

 sets almost due west, having by this time 

 become a conspicuous object in the early 

 evening sky. Venus will remain with us 

 throughout the winter and spring, in- 

 creasing in brightness and mounting 

 higher in the sky on each successive eve- 

 ning. It will reach its greatest distance 

 east of the sun on April 23, (when it will 

 remain in the western sky until nearly 

 midnight) and it will attain its greatest 

 brilliance on ]\Iay 27. 



Mars will be a most interesting object 

 for observation during the present month. 

 Its very rapid, direct motion' which for 

 so long a time has kept it beyond the 

 borders of our evening star map, will 

 cease on January i, at 9 P.M., and from 

 this time until Alarch 22 it will move west- 

 ward among the stars. During January 

 it will be seen in the constellation Leo, 

 just within the blade of the Sickle. This 

 most interesting- planet is now in almost 

 the best position for observation of the 

 entire year. It reaches its least distance 

 from the earth on February 9, and 

 throughoutthe month of January the earth 

 and Mars are so unusually near together 

 that the planet can be studied to the great- 

 est advantage. The reader may remem- 

 ber how faint the Red Planet looked only 

 a few months ago. It has now approached 



