Tuesday, February 21, 2006 05:53 AM
An eclipse (Greek verb: ecleipo, "to cease existing" or calypse, "to cover" ) is an astronomical event that occurs when one celestial object moves into the shadow of another.
The term is most often used to describe either a solar eclipse, when the Moon's shadow crosses Earth's surface, or a lunar eclipse, when the Moon moves into the shadow of Earth. However, it can also refer to such events beyond the Earth-Moon system: for example, a planet moving into the shadow cast by one of its moons, a moon passing into the shadow cast by its parent planet, or a moon passing into the shadow of another moon. A solar eclipse is actually a misnomer; the phenomenon is actually an occultation.
Or read here: http://www.eclipse.org/org/#about