Venus Mysteries Blamed on Colossal Collision: Venus is made of the same stuff of Earth, but is bone-dry, hot enough to melt lead and has a chokingly thick atmosphere. It even spins backwards. Astronomers have spent decades trying to explain Venus' mysterious properties. Now one scientist thinks the planet's formation may explain all: Two huge, protoplanetary bodies collided head-on and merged to form our planetary neighbor, but obliterated nearly all water in the process. "The probability that two protoplanets collided to form Venus is not at all implausible," said John Huw Davies, a geodynamicist at Cardiff University in the U.K. who developed the idea. A majority of scientists think Earth's moon formed when a protoplanet about the size of Mars smacked into the planet at an angle. Davies thinks Venus was born of a far worse cosmic train wreck. "What if the moon-Earth collision isn't that big in planetary terms?" Davies told SPACE.com . "A he...