This is a fascinating collection of Gailileo's writings on his discovery of Jupiter's moons and his observation and speculations on the nature of sunspots, as well as his defense of the veracity of his observations in the face of heavy censure from the Church. Any amateur astronomer who remembers seeing Jupiter's moons for the first time through a telescope and witnessing the change in their configuration from night to night will get a thrill out of reading this first account and Galileo's extraordinary reasoning as to why they must be satellites of the planet Jupiter and why this confirms the heliocentric model. Galileo was an excellent rhetorician who also surprisingly had a sense of humor when dealing with the absurdity of his critics' claims. I thoroughly loved this book and recommend it to anyone even mildly interested in the history of astronomy. ( )