During breakfast on June 30, 1908, a man named S.B. Semenov was sitting on a porch at a northern Russian trading post when the sky burst into flames. He looked up and saw the heavens appear to split apart, and he felt as though his shirt was on fire; after a moment, a heavy blow knocked him off his feet and he passed out. The inferno, afterward known as the Tunguska Event, was a high-altitude explosion of a meteor or a comet--but nobody ever found the remains.
Most independent inventors don’t have bottomless bank accounts. To fund their dreams, many innovators are appealing to strangers on the Web for help. Kickstarter co-founder Yancey Strickler weighs in on this growing source of grassroots venture capital.
Five amazing, clean technologies that will set us free, in this month's energy-focused issue. Also: how to build a better bomb detector, the robotic toys that are raising your children, a human catapult, the world's smallest arcade, and much more.