In this book, the famous astrophysicist and writer Mario Livio turns to the figure of Galileo Galilei, arguing that today his life path, scientific research and desire to understand the world are more relevant than ever. The scientist's discoveries, based on tireless observations and ingenious experiments, contradicted generally accepted ideas and the position of the Catholic Church of that time. As a result, Galileo was put on trial and his life was in danger. In the face of global challenges, such as climate change on the planet, modern scientists, like Galileo 400 years ago, are faced with distrust of research, denial of its results, and ignoring of conclusions. Therefore, to this day, Galileo remains a hero and a source of inspiration for scientists and all those who honor and are ready to defend scientific truth.