On this day in 1908, the Tunguska impact forever changed the earths surface. An asteroid collided with the earths surface in Siberia, causing a giant explosion. And, approximately 770 square miles of land was flattened. But, there are no known human casualties. So, in 2014, Dr. Brian May, Danica Remy, Rusty Schweickart and Grig Richters created the day to inspire the world about asteroids.