frequently observed on the sun, other evidence of which we have in 

 the auroral displays, and other magnetic influences which the sun 

 produces upon the earth. 



The planet Mars is a very interesting object to observe in a good 

 telescope. The general surface is of a strong yellowish color, but 

 there are large dark markings which are sometimes of a greenish 

 color, and some parts of which are subject to probably a seasonal 

 variation. There are also white polar caps; in the winter of the 

 planet these extend down to middle latitudes, and in the summer 

 melt to small size, which suggests that they are probably due to snow. 



POLAR CAPS 



In the south polar regions of Mars there seem to be mountain 

 ranges. Their presence is revealed by the melting polar cap, which 

 always leaves behind it at these places white strips that more slowly 

 melt away. These white strips seem to be due to snow on consider- 

 able elevations. 



The rotation of the planet can be seen readily, even in telescopes 

 of four or five inches aperture, by watching it for a short time. This 

 rotation is also clearly shown on photographs of Mars. The length 

 of its day, from such observations, is about thirty-seven minutes 

 longer than our day. Mars rises in the east at about sunset now. 

 It can be readily recognized by its red color, and by being the bright- 

 est object in that part of the sky. 



41 



