ASTRONOMY. 



rise some minutes before the Sun, is found to be 

 progressive, that is, his right ascension, if obser- 

 ved from day to day, continually increases. The 

 right ascension of the Sun, however, increases fas- 

 ter, so that Mars recedes from the Sun toward the 

 west, though his real motion, with respect to the 

 fixed stars, is toward the east. The motion, how- 

 ever, is continually growing slower, and at the end 

 of a year nearly, the angular distance from the Sun 

 being then between 136 and 137, the planet 

 becomes stationary, and is without any sensible 

 motion for a few 4ays. 



The motion then becomes retrograde, or toward the 

 west, and continues so till Mars be 180 distant 

 from the Sun, or in opposition, so as to be on the 

 meridian at midnight. The retrograde motion is 

 then swiftest ; it afterwards becomes gradually 

 slower, and ceases altogether when the planet has 

 again come to be between 136 and 137 dis- 

 tant from the sun on the other side. The motion 

 becomes then progressive, and continues so till the 

 conjunction, and beyond it, in the manner just 

 described. 



I . The same is true, with certain variations, of all the 

 other planets. The longer the period, and the 

 znoredistant the planet from the Sun, the longer the 

 time, and the smaller the arc of retrogradation. 



For 



