An eclipse is simply the shadow cast by one body upon another, when it passes in front of a source of light. There are two categories of eclipse of interest to observers on the Earth, both of which owe their existence to the fact that the Moon orbits around the Earth: Lunar and Solar eclipses.

The following pages provide more detail on the workings of eclipses:

For those who are interested in delving a little deeper into the science, here is some more detailed information: