*24 SCIENTIFIC RECREATIONS. 



Mars moves upon his axis in about twenty-four hours and a half, and takes 

 rather more than 686 days to revolve round the sun. (See page 489.) Thus 



its days are a little longer than, and its 

 years twice as long as our days and 

 years. When in " opposition," or on 

 the opposite side of us from the sun, 

 Mars is at his brightest. This happened 

 in September 1877. He will come close 

 again to us in 1892. 



All planets are wanderers, but of 

 all the wanderers Mars has the most 

 eccentric orbit. He curls about, so to 

 speak, in loops and curves in a very 

 irregular manner, and therefore his dis- 

 tance from the earth varies very con- 

 siderably ; and this eccentric behaviour 



of the warlike planet must have, as we believe it did, puzzled the ancients 

 very much. But and here reason came to human aid this very fact, this 

 great eccentricity of the planetary motions, caused Copernicus to investigate 

 the subject with great attention, and he at length explained the true reason 

 of these irregular orbits from the hypothesis that it was around the sun, and 

 not around the earth that the planets moved in regular orbits. 



It is quite ascertained that Mars is very like our earth in miniature. 

 We annex a diagram of the plan et, and when it is examined with a good 

 telescope the seas and continents can be quite distinctly perceived. At the 

 poles there appears to be a white or snowy region at varying periods, which 

 would lead us to the conclusion that the atmospheric changes and the seasons 

 are similar to our own ; and as the inclination of the planet is nea'rly the 

 same as the earth, this supposition may be accepted as a fact. 



Thus we see that Mars is the most like 

 earth of all the planets, and its inhabitants 

 if, indeed, it is now inhabited must have a 

 beautiful view of us when the weather is fine, 

 for we are so much larger. Mars is also at- 

 tended by two satellites, or moons, as Pro- 

 fessor Hall reported from Washington in 

 1877. These moons have been named 

 Dcimos and PJiobos^ and are both very small, 

 their diameter being only about six miles ; 

 but late astronomers have reasoned that they 

 must be three times this diameter. 



There have been numerous theories 



, . i i , i t r Fig. 582. Earth seen from Mars. 



concerning Mars being inhabited, and of 



course these suggestions made respecting life on one planet may, with 



varying circumstances, be applied to another. Each planet may have had, 



