THE MINOR PLANETS. 



parts to them that peculiar color. The greenish portions he inferred to be 

 seas. 



Among the features apparent on this planet, what attracted most attention 

 are certain white spots seen around the polar regions. These were among the 

 very first permanent marks discovered on the planet, and are represented even 

 in the first rude drawing given of its telescopic appearances in the proceedings 

 of the Royal Society. In the observations of Herschel both father and son 

 they have, however, been more rigorously examined and described ; and still 

 more so in the investigations of Beer and Madler. 



It has been ascertained from the changes they undergo that they must be 

 produced by deposites of snow in the polar regions. Herschel observed that 

 when the pole had been turned from the sun during the winter, and first re- 

 appeared in the spring of the planet, the whiteness was most extensive and 

 vivid ; and that when the same pole was exposed to the influence of the sun 

 during the summer, which is double the length of the summer upon the earth, 

 this whiteness gradually diminished, and always disappeared. Such indica- 

 tions cannot be mistaken, and admit of no other explanations save what I have 

 now adverted to. 



The elaborate observations of Beer and Madler have supplied various tele- 

 scopic views of this planet. In their work upon this subject they have pub- 

 lished forty views of hemispheres made by planes passing nearly through the 

 poles, which is the only view presented to the observer by the planet. Hav- 

 ing, by combining together many observations, made as it were a survey of 

 the entire surface of the globe of Mars, they have given two views, one of its 

 northern and the other pf its southern hemisphere. 



We have obtained copies of these views, and have affixed them here. 

 Two of the views of this planet, bounded by a circle passing nearly through 

 its poles, are annexed. The views of the hemispheres are given on page 12. 



HAS MARS A SATELLITE ? 



Analogy naturally suggests the probability that the planet Mars might have 

 a moon. These attendants appear to be supplied to the planets in augmented 

 numbers as they recede from the sun ; and if this analogy were complete, it 

 would justify the inference that Mars must at least have one, being more re- i 

 mote from the sun than the earth, which is supplied with a satellite. No \ 

 < moon has ever been discovered in connexion with Mars. It has, however, * 

 been contended that we are not therefore to conclude that the planet is desti- < 

 tute of such an appendage ; for as all secondary planets are much less than ) 

 their primaries, and as Mars is by far the smallest of the superioi planets, its < 

 satellite, if such existed, must be extremely small. The second satellite of | 

 Jupiter is only the forty-third part of the diameter of the planet ; and a satellite ^ 

 which would only be the forty-third part of the diameter of Mars, would be S 

 under one hundred miles in diameter. Such an object could scarcely be dis- ( 



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