THE HEAVENS FOR DECEMBER 



209 



tune is too faint to be seen with the 

 naked eye. In the telescope it appears 

 as a small, greenish disc on which no 

 markings can be seen, attended by a 

 single satellite which is of almost ex- 

 actly the same size as our own moon 

 and at almost the same distance away 

 from its planet. But the planet itseli 

 is a ball of heated vapor no less than 

 35,000 miles in diameter and is there- 

 fore a very different world from our. 

 THE NEW COMETS. 

 The first comet of the year was dis- 

 covered toward the close of Septem- 

 ber, at which time it was far below the 



was discovered in the constellation 

 Sextans, a little west of the brightest 

 star of the Lion, which is now a con- 

 stellation of the morning sky. This 

 object is moving rapidly southward and 

 is not now visible in northern latitudes. 

 Computations indicate that it is iden- 

 tical with a comet first seen in 1790 and 

 again discovered in 1858, and whose 

 return was looked for toward the close 

 of the present year. These are the only 

 new comets of the present year. It is 

 quite unusual for so many months to 

 pass without our being favored with at 

 least a few of these celestial visitors. 



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Figure 2. The square of Figure 1 enlarged to show the motion and present position of the planet Neptune. 



equator in the southern sky. Since this 

 time it has been moving almost exactly 

 northward among the stars, and 

 throughout December will be visible 

 low in the northwest. The comet is a 

 faint, telescopic object and it will con- 

 tinually grow fainter because it is re- 

 ceding both from the sun and from 

 the earth. When brightest it was seen 

 to have a diffuse head, of an apparent 

 diameter about one-sixth that of the 

 moon, and a faint, slender tail. 



On October 18 a second faint comet 



THE PEANETS IN DECEMBER. 



Mercury enters the morning sky on 

 December 8 and reaches its greatest 

 distance west of the sun on December 

 28. At the latter date an unusually fav- 

 orable oppoitunity will be afforded for 

 viewing it, for it will then rise in the 

 east more than one hour and a half be- 

 fore sunrise. 



Venus will be seen shining most con- 

 spicuously in the southwestern sky in 

 the early evenings throughout the 

 month. 



