This podcast episode explores the field of planetary defense and the threat of asteroids. Edgar Rivera Valentin, an expert in planetary defense, discusses the importance of learning from past asteroid impacts to predict and prevent future ones. The episode highlights Edgar's connection to the Arecibo telescope in Puerto Rico, the world's largest radio telescope used to study potentially dangerous asteroids. The work of planetary defenders in measuring the distance and movement of asteroids towards Earth is also discussed. The episode concludes with the mention of the asteroid Apophis and the damage suffered by the Arecibo telescope in 2020.