What

An eclipse is simply the shadow cast by one body upon another, when it passes in front of a source of light. That might sound pretty boring, but there are two types of eclipse that are very interesting indeed:

• A Solar eclipse occurs in daytime when the New Moon -- normally not visible during daytime -- passes directly in front of the Sun, and casts its shadow on the Earth. In the middle of the day, you see the Moon move over the Sun, and in a total solar eclipse, the Sun is completely blacked out for a few seconds, or even minutes.

• In a Lunar eclipse, the Moon passes through the Earth's shadow. In the night of a Full Moon, when a lunar eclipse occurs, you can see the Earth's shadow move over the moon; in a total lunar eclipse, the Moon is tinted a deep copper-red by the Earth's atmosphere.

What effect does an eclipse have on the Earth? In terms of large-scale effects, none! Any of the usual disaster stories you might hear, about how the alignment of the Sun and Moon is going to cause earthquakes, volcanoes, etc., are pure baloney. Total solar eclipses, planetary alignments, etc., have been happening since the solar system was created 5 billion years ago, with no ill effects. Actually, the Sun and Moon come into alignment with the Earth twice every month; this causes Spring and Neap tides, but nothing else. An eclipse is no different in that regard.

However, the visual effects of an eclipse are, of course, totally spectacular! A total solar eclipse, in particular, is the most amazing astronomical spectacle that can be seen from the Earth, and something that everyone should try to see in their lifetime at least once.

The following pages provide more information on what an eclipse is all about:

	A Solar Eclipse What happens during a solar eclipse.
	A Lunar Eclipse What happens during a lunar eclipse.
	Observing Some hints on the best ways to observe an eclipse, including pointers to information on safely photographing an eclipse.
	Eye Safety Looking at the Sun without precautions -- at any time -- can damage your eyes; since people tend to look at the Sun more during a solar eclipse, this page has some advice on eye safety during a solar eclipse.
	When Having read about what an eclipse is, I'm sure you're going to want to know when you can see one; so here are timetables and maps for past and future eclipses, and even a searchable eclipse database.
	Why For the curious-minded, here's a collection of pages explaining why and how eclipses happen.