What do the nodes of the lunar orbit have to do with eclipses?
There are two orbit locations where eclipses can occur. These are the points in the lunar orbit that intersect the ecliptic plane where the Sun moves in the sky. Called the ascending node and the descending node, eclipses can occur at either node. The Moon must be in the full moon phase as it passes the node in order for a lunar eclipse to occur. Similarly, solar eclipses only occur during new moon when this phase occurs at either node.