In this book, the renowned astrophysicist and writer Mario Livio turns to the figure of Galileo Galilei, arguing that today his life path, scientific search, and desire to understand the world are more relevant than ever. The scientist’s discoveries, based on tireless observations and brilliant experiments, contradicted the prevailing ideas and the position of the Catholic Church of that time. In the end, Galileo was put on trial, and his life was placed in danger. In the face of global challenges such as climate change on the planet, modern scientists—just as Galileo did 400 years ago—are confronted with distrust of research, denial of its results, and ignoring conclusions. Therefore, to this day, Galileo remains a hero and a source of inspiration for scientists and everyone who values and is ready to defend scientific truth.