380 



Professor H. H. Turner 



[June 5, 



receive light for 80 minutes, so that we should still see Saturn 

 shining with reflected sunlight for more than an hour after the Sun 

 had gone out. If the Sun were suddenly set ablaze again, we should 

 be illuminated eight minutes afterwards, but it would be more than 

 an hour before we saw Saturn. 



Now suppose that we were at a great distance from the solar 

 system, in a direction perpendicular to the planes of the planetary 

 orbits, and that the Sun, originally dark, were to flame up suddenly 

 to great brightness for one minute only, as Nova Persei did. Then 

 after eight minutes we should see a speck of light appear where the 

 Earth happened to be, or if there were, instead of a single Earth, a 



number of small earths scattered round its orbit, we should see a ring 

 of light instead of a speck ; and the illuminated ring would last just 

 one minute and then disappear. After 80 minutes we should see 

 Saturn as a speck of light, or again if we suppose him spread round 

 his orbit, we should see this wider ring. If there were enough 

 intermediate planets the appearance would be that of a continually 

 expanding ring of light, similar to the expanding ripple when a stone 

 is thrown into water. It is not the water which expands, but the 

 wave motion, and so it is not, in the case of Nova Persei, actual 

 matter which is exploded outwards, but illumination which lights up 

 successively matter which was already there. The supposition is 



