TO KNOW THE STARRY HEAVENS 



21 



1 1 will be noticed that even when 

 the center of the moon is at B the moon 

 is so far from the center of the shadow- 

 that this eclipse barely misses being 

 only a partial one. The moon will, in 

 fact, remain wholly immersed in the 

 shadow for only sixteen minutes and 

 thirty seconds. As much sunlight is 

 usually bent within the shadow by re- 

 fraction as it passes through the rim o1 

 air surrounding the earth, the upper 

 portion of the moon will at this time 



fortunate that this planet has been for 

 many months so very far below the 

 equator that it could only be seen low 

 in the southwestern sky. It moves up- 

 ward quite rapidly during December, 

 but as it also draws nearer the sun its 

 time of setting will remain nearly con- 

 stant. 



Mars moves rapidly eastward dur- 

 ing the month, passing from the east- 

 ern borders of Leo into the constella- 

 tion \ 'irgo. It rises a little to the north 



Figure 3. Passage of the moon through the earth's shadow on December 28. The lower figure shows 

 the appearance of the partly eclipsed moon at various hours. 



doubtless be far more darkened than 

 the lower portion and the latter will 

 very probably present an ever-chang- 

 ing reddish and greenish combination. 



The Planets in December. 



The planet Mercury will reach its 

 greatest distance to the east of the 

 sun's rays on the morning of December 

 17. For a few evenings before and af- 

 ter this date it may be seen shining in 

 the twilight glow, very far toward the 

 southwest, for somewhat more than 

 one hour after sunset. 



Venus, which reached its greatest 

 eastern elongation on November 30, re- 

 mains our very conspicuous evening 

 star throughout the month. It is un- 



of the east point of the horizon at about 

 11.30 P. M., but is not sufficiently high 

 in the sky for satisfactory observation 

 until well after midnight. 



Jupiter remains the most brilliant ob- 

 ject in the eastern heavens, riding high 

 in the sky, in excellent position for ob- 

 servation. An interesting phenomenon 

 of its satellites may be seen during the 

 nights of December 1, 6, 8, 15, 17, 22, 24 

 and 31. 



This month witnesses the entrance 

 of the beautiful Saturn into our even- 

 ing heavens. This planet, which, like 

 Jupiter, is slowly retrograding, will be 

 seen to rise at about 9 P. M. on Decem- 

 ber t and so earlv as 7 P. M. on Decem- 

 ber 31. Throughout the winter it will 



