The end of humanity has been a topic of great concern across ages and civilizations. Over the last several decades, studies have allowed us to better understand the most likely threats to life on Earth, both in the past and the future. IAU Symposium 374 covers potential hazards caused by astronomical phenomena. These proceedings present a comparative analysis of these possible astronomical catastrophes that could lead to a new extinction. Throughout the volume, the authors analyse different aspects of the main risk identified: the impact of near-Earth asteroids and the meteor phenomena. The discovery, monitoring and dynamical evolution of near-Earth asteroids are discussed. This symposium represents one of the first attempts to address the transdisciplinary topic of life-threatening hazards originating from beyond our planet, including current and future mitigation strategies.