From day to day, most of us live in blissful ignorance about the dangers surrounding us. We get up, go to work, come home, spend time with family and friends, and repeat it all over again. Rarely do we think the world could end at any moment. Of course, thankfully, the apocalypse hasn’t happened yet. However, in years past, the world has come incredibly close to ending or at least significantly changing. From interstellar projectiles to microscopic menaces, these are 25 scary world events that could have ended life as we know it.