Bruno was brilliant, contentious, and ultimately self-destructive. There is nothing in his writings that contributed to our knowledge of astronomy in any substantial way, indeed his astronomical writings reveal a poor grasp of the subject on several important points. Copernicanism, an idea which was to become the key insight that led to our view of the world. In addition, his On the Infinite Universe and Worlds appeals to many today because of its apparent resonance with the deeply held conviction that life exists elsewhere in the Universe, despite the fact that proponents of extraterrestrial life would find little of interest within its difficult pages. It also does not hurt his mystique that he came to a rather spectacular and violent ending, ostensibly in punishment for these beliefs by the reigning authorities of his day.
History is funny that way.
The SETI League, Inc.