Astronomy 104: Lecture 3 (Slide 6)

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The Moon's Orbital Plane:

Orbital Inclination: the Moon's orbit is inclined by 5° relative to the Ecliptic.

Because of this inclination, the orbit of the Moon crosses the ecliptic in only two places that are analogous to the Vernal and Autumnal Equinoxes.

For the Moon, these points are called the

Ascending Node: The point in its orbit where the Moon crosses the plane of the Ecliptic moving Northward.
Descending Node: The point in its orbit where the Moon crosses the plane of the Ecliptic moving Southward.

Connecting these two points is the Line of Nodes:

Furthermore, since the Moon stays close to the Ecliptic, it will be higher in the sky in the Summer and lower in the sky in the Winter, just like the Sun.

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