1 3 4 Science Religion and Reality 



of the known planets, Saturn, was investigated. Peculiar appear- 

 ances in him were noted by Galileo, though their interpretation as 

 rings was the work of Christian Huygens (i 629-1 695) at a later 

 date. 



Among the most important of all the observations of the year 

 1 610 were those on the inner planets and notably on Venus. It 

 had been a real objection to the Copernican hypothesis that if the 

 planets resemble the earth in revolving round a central sun, they 

 might be expected to be luminous only when exposed to the sun's 

 rays. In other words, they should exhibit phases like the moon. 

 Such phases in Venus were now actually observed and described 

 by Galileo. 



At this time, though Galileo had earned the enmity of the 

 Aristotelians, he was not yet in bad grace with the heads of the 

 Church. In the year 161 1 he repaired to Rome to exhibit his 

 " celestial novelties " and was well received by Pope Paul V. It 

 was about this time that he first observed dark spots on the surface 

 of the sun. These, he noted, narrowed continuously as they 

 approached the edges of the sun's disc. He rightly regarded this 

 process as foreshortening and as indicating that they were on the 

 surface of the sun's orb. The date and circumstance of the 

 announcement were unfortunate, since they involved him in a con- 

 troversy with a powerful Jesuit rival who not only claimed priority 

 of observation but also put another interpretation on the spots. 

 The controversy spread far beyond its original focus. We shall 

 not follow it. An aspect of the dispute, however, was the question 

 of the habitability of the moon and planets. His critics believed 

 that this was a natural corollary of Galileo's development of the 

 Copernican hypothesis which he had now openly espoused. The 

 habitability of the moon was contrary to what vras regarded as 

 Aristotelian and Christian doctrine. 



Thus became united against Galileo a variety of interests. 

 The band of Academic Aristotelians had long been fuming against 

 him, the Jesuits and some political churchmen now joined them, 

 and with them were united many of that intellectually timid and 

 novelty-hating class that forms the mass of every population in 

 every age. From at least 161 4 onward sermons were preached 

 against him. The opposition was gaining force. The matter 

 came before the Inquisition early in 161 6 and Cardinal Bellarmine 

 was directed " to admonish Galileo to abandon these opinions and. 



