http://www.newsweek.com/moon-earth-distance-orbit-958404 > More than a billion years ago, a day on Earth lasted just 18 hours, a new study reports. The distance from our planet to the moon, scientists say, is one major reason for the extra six hours we have today. > Our faithful rocky companion used to lie far closer to our planet—close enough to alter the way it moves, researchers reported Monday in Proceedings of the National Academy of Sciences.