The Earth moves in an elliptical orbit, with the Sun as one of its foci. The plane of this ellipse is called the ecliptic.The Moon also moves around an elliptical orbit, with the Earth as a focus. The plane of this ellipse is at an angle of 5º 9’ to the ecliptic. As it moves around the Earth, the Moon
therefore crosses the ecliptic twice: once when descending – this is the descending node (), and once when ascending – which is the ascending node ().