A “violent encounter with Jupiter” may have hurled a fifth gas giant out of our solar system billions of years ago. A simulation done by the Southwest Research Institute in Boulder, Colorado suggests that our solar system may have included another gaseous giant, placed between Saturn and Uranus. The computer models may prove how the planets of our solar system settled in their current position, a long-standing source of mystery to astronomers.
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.