CHAPTEK Xll. 



MARS AS A WORLD. 



IT is rather curious that the planets should so closely 

 simulate the guise of the fixed stars. Saturn and Mars, 

 two of the most celebrated planets, have often a superficial 

 resemblance to Aldebaran or Betelgeuse. Yet it is diffi- 

 cult to emphasize sufficiently how wide is the actual 

 difference between them. The planets are not self-lumi- 

 nous bodies like the stars ; they are merely orbs revolving 

 around the sun, and indebted, like our earth, to the sun 

 for the benefit of his light and heat. These planets are 

 bodies which must be generally, if not always, smaller 

 than the fixed stars ; and their apparent brilliancy, not- 

 withstanding their small size and the fact that they 

 exhibit only reflected light, is simply a consequence of 

 their comparative nearness. 



The apparent resemblance between planets and stars is 

 quickly dispelled when a telescope is directed towards 

 them. The star, as we have stated, shows merely a 

 bright point of light. It is far otherwise when we look 

 at the planets. Each of them exhibits in any instrument, 

 even of moderate power, a characteristic appearance by 

 which the planet is at once distinguished from the stars, 



