The Moon may have formed intact just hours after a giant collision

Scientists have discovered that the Moon-forming collision may have depended heavily on how hot and physically strong early Earth and Theia were. New simulations found that some impacts create the familiar disk of debris that later becomes the Moon, while others can produce an intact Moon in only about five hours. The results challenge the long-standing assumption that the enormous collision could be modeled as if both worlds behaved mostly like fluids.