EXCURSIONS ON THE PLANETS—RUDAUX 191 
ous celestial arch would cease to be visible so that the polar inhabi- 
tants of Saturn must be completely ignorant of its existence. 
We are now very far away from the sun which will appear in 
the sky of Saturn only as a small disk ten times smaller in diameter 
and shining with one hundred times less light. For us earth 
dwellers that would be a melancholy illumination. But what would 
we say if there were possibilities of going yet farther off toward the 
planets Uranus and Neptune, where our sun would be reduced in 
grandeur to the appearance of a bright star shining with respectively 
four hundred and nine hundred times less ight than we receive on 
the earth. 
