A GIANT PLANET. IOI 



effect whatever on the condition of Jupiter's atmo- 

 sphere ! 



Now, as respects the alternation of summer and 

 winter, we can form no satisfactory opinion in Jupiter's 

 case, because he has no seasons worth mentioning. For 

 instance, in latitudes on Jupiter corresponding to our 

 own, the difference between extreme winter and extreme 

 summer corresponds to the difference between the 

 warmth on March 12 and March 28, or between the 

 warmth on September 15 and on September 31. Yet 

 we are not without evidence as to seasonal meteoro- 

 logical effects in the case of the sun's outer family of 

 planets. Saturn, a belted planet like Jupiter, and in 

 all other respects resembling him so far as telescopic 

 study can be trusted, has seasons even more markedly 

 contrasted than those on our own earth. We see now 

 one pole now another bowed towards us, and his equa- 

 torial zone is curved now downwards now upwards, so 

 as to form two half ovals (at these opposite seasons), 

 which, taken together, would make an ellipse about 

 half as broad as it is long. As no less than fourteen 

 years and a, half separate the Saturnian summer and 

 winter, we might fairly expect that the sun's action 

 would have time to exert itself. In particular, we 

 might fairly expect the great equatorial zone to be 

 displaced ; for our terrestrial zone of calms or ' dol- 

 drums ' travels north and south of the equator as the 

 sun shifts northwards and southwards of the celestial 

 equator, accomplishing in this way a range of no less 

 than 3,000 miles. But the Saturnian equatorial zone 



