Lunar Cycles • A visual guide

Lunar Nodes

Where the Moon’s orbit crosses the ecliptic

The Moon’s path is tilted relative to Earth’s orbital plane. Its crossings of that plane are called nodes.

Scroll the diagram sideways to explore its labels.

An unfolded schematic of the Moon’s passage north and south of the ecliptic. Read left to right. This is a conceptual sequence, not the shape of its orbit or a graph of calculated positions. Original LuNAC illustration; conceptual basis: Fred Espenak, NASA GSFC — Eclipses and the Moon’s Orbit.

The reference plane

The ecliptic is the plane of Earth’s orbit around the Sun. The Moon’s orbital plane is tilted relative to it. A node is a crossing location defined by this geometry, rather than a physical object in space.

Source: Fred Espenak, NASA GSFC — Eclipses and the Moon’s Orbit

Ascending and descending

At the ascending node, the Moon crosses from south of the ecliptic to north. At the descending node, it crosses from north to south. These directions refer to the ecliptic, rather than movement up or down in your local sky.

Source: Astronomy Engine — Lunar node definitions

Why nodes matter for eclipses

An eclipse requires a new or full moon near a node, with the Sun, Earth, and Moon aligned closely enough for a shadow to fall on Earth or the Moon. A node crossing alone does not produce an eclipse, and the Moon need not be exactly at the node.

Source: Fred Espenak, NASA GSFC — Eclipses and the Moon’s Orbit