There was once a civilization on Mars, but their atmosphere was destroyed when a nearby planet called Maldek—positioned between Mars and Jupiter—blew up after its own inhabitants messed with immense power they couldn’t control. That explosion created today’s asteroid belt. Earth, luckily, was on the far side of the solar system at the time, but fragments still made it here—one of them likely slammed into what’s now Mexico and wiped out the dinosaurs.