Astronomy. 



[Lecture 19, 



TABL E of the solidity of the sun and of the pri- 

 mary planets compared with that of the earth. 



The proper motion of each of the primary 

 planets is from west to east in an elliptical orbit, 

 (PL XXVI. fig. 112.) AEPG, the sun forming 

 one of the foci. The plane of the orbit of the 

 earth is called the ecliptic, as I have before ex- 

 plained. The orbits of all the other planets are 

 differently inclined to it, but there is not any of 

 tlie old planets which departs more than eight 

 degrees from the ecliptic ; so that they are all 

 contained within the zodiac. It is this departure 

 from the ecliptic, which is called the latitude of 

 the planets, in like manner as the latitude of the 

 stars denotes their distance from the ecliptic. 



