NEWS FROM JUPITER. 
355 
ture of Jupiter, in his interesting and valuable work called 
“ The Fuel of the Sun.” I fully agree with him in regarding 
it as a reasonable assumption, though I cannot go so far as to 
regard it as certain, that every planet has an atmosphere whose 
mass corresponds with, or is even perhaps actually proportional 
to, the mass of the planet it surrounds. If we make such an 
assumption in the case of Jupiter, we arrive at conclusions 
closely resembling those to which I have been led by the above 
process of reasoning. 
Thus many lines of evidence, and some of them absolutely 
demonstrative, in my opinion, point to the conclusion that 
Jupiter is an orb instinct with fiery energy, aglow it may well 
be with an intense light which is only prevented from mani- 
festing itself by the cloudy envelope which enshrouds the 
planet. 
But so soon as we regard the actual phenomena presented by 
Jupiter in the light of this hypothesis, we find the means of 
readily interpreting what otherwise would appear most per- 
plexing. Chief among the phenomena thus accounted for, I 
would place the recent colour-changes in the equatorial zone of 
Jupiter. 
What, at a first view, could appear more surprising than a 
change affecting the colour of a zone-shaped region whose sur- 
face is many times greater than the whole surface of our earth. 
It is true that a brief change might be readily explained as 
due to such changes as occur in our own air. Large regions of 
the earth are at one time cloud-covered and at another free 
from clouds. Such regions, seen from Venus or Mercury, would 
at one time appear white, and at the other would show whatever 
colour the actual surface of the ground might possess when 
viewed as a whole. But it seems altogether impossible to ex- 
plain in this way a change or series of changes occupying many 
years, as in the case of the recent colour-changes of Jupiter’s 
belt. Let me not be misunderstood. I am not urging that 
the changes in Jupiter are not due to the formation and dis- 
sipation of clouds in his atmosphere. On the contrary, I 
believe that they are. What seems to me incredible, is the 
supposition that we have here to deal with such changes as 
occur in our own air in consequence of solar action. 
I do not lose sight of the fact that the Jovian year is of 
long duration, and that whatever changes take place in the 
atmosphere of Jupiter through solar action might be expected 
to be exceedingly slow. Nay, it is one of the strongest argu- 
ments against the theory that solar action is chiefly in 
question, that any solar changes would be so slight as to be in 
effect scarcely perceptible- It is not commonly insisted upon 
in our text-books of astronomy — in fact, I have never seen the 
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