Any help please? Explain the term "Line of Nodes" and how it relates to lunar and solar eclipses.?

Answer 1

The "line of nodes" is the intersection between the plane of the Moon's orbit around the earth and the plane of the Earth's orbit around the Sun.

The orbit of the moon around the earth is inclined (tilted) a small amount (about 5 degrees) relative to the Earth's path around the sun. Eclipses only occur when all three lie in about a straight line, so not only does the moon have to be full (for a solar) or new (for a lunar), it also has to be in the right position in its tilted orbit to be passing through the plane of the Earth's orbit (in the line of nodes).

You can imagine this tilted plane of the moon's orbit being attached to the Earth as the Earth circles the sun during a year. While the moon will pass through the nodes twice each orbit, it is easy to see that only about twice a year will the moon pass through those nodes ***while it is full or new***. The cycle actually ends up being ~14 months...dunno why. Maybe the tilt of the moon's orbit precesses quickly. Maybe that wiki article that other answer linked to explains that.

Answer 2

Its an intersetion of two orbital planes this link explains it best