Astronomy. [Lecture 19, 



but seldom viable. No spots bare as jet been 

 discovered on his surface, and therefore bis ro- 

 tation on bis axis is not known. Mercury and 

 Venus, being inferior planets, can never appear 

 quite at the full to us, but must show phases 

 analogous to those of the moon, according to 

 their relative positions as to the sun and the 

 earth. 



Yews is the most brilliant in appearance of 

 all the planets; and she is called the morning or 

 evening star, according as she precedes or fol- 

 lows the sun; m the first case she appears^ to the 

 right, in the second to the left of that luminary. 

 Some spots bare been discovered on her surface, 

 yet her rotation on her axis has not been posi- 

 tively ascertained. She is said to be surrounded 

 by an atmosphere of about fifty mile* in height, 



MA*S, the first of the superior planets, is dis- 

 tinguishable from the rest by the red appearance 

 of his disc, which all agree in attributing to the 

 density of his atmosphere. His figure is an ob- 

 late spheroid, like that of the earth, which in- 

 deed be resembles most in all circumstances. 

 Spots have been observed on bis surface, from 

 which bis diurnal rotation has been ascertained, 

 as well as the inclination of his axis to the eclip- 

 tic, which is 59* 4. Two large white circular 

 spots are observed at bis poles, whence it is con- 

 jectured that they are continually covered with 

 snow. 



PALLAS, Jrao, and VESTA, are too 



