Has the moon always been so close?
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Published in Daily Trivia
It used to be much closer! A billion years ago, the moon was in a tighter orbit, taking just 20 days to go around us and make a month. A day on Earth back then was only 18 hours long. The moon is still moving away - about 1.6 inches (4 centimeters) a year. Meanwhile, Earth's rotation is slowing down, lengthening our days. In the distant future, a day will be 960 hours long!