This simulation shows that the lunar cycle has changed significantly since the moon formed roughly 4.5 billion years ago. On the left, a 24,000-year-old moon moves in a short, highly elliptical orbit. This oblong orbit results in a fast lunar cycle and a moon that bobs toward and away from Earth as the yellow outlines of constellations whip by. On the right, the present-day moon orbits in a relatively circular pattern about once every 27 days. Read more: http://ow.ly/KBkKy Credit: E. Noordeh and