Moon moves eastward, rising later each day and passing through phases monthly. Chinese, Chaldean, and Mayan calendars attempted to reconcile Moon's movements. Newton used lunar observations to develop gravity theory in late 17th century. Modern observations improved accuracy through numerical integration and telescopes
Moon phases occur every 29.5 days due to Sun's illumination. Moon has day and night sides that change with rotation. Moon orbits Earth in elliptical path, completing revolution in 27.3 days
Based on sun's movement, one day equals one year in life. Other planets move proportionally according to ephemeris positions. Commonly used predictive method for long-term inner developments