In astronomy, an eclipse is where various planetary bodies align and block the light from the sun. In a lunar eclipse, the Earth comes between the sun and the moon. In a solar eclipse, the moon comes between the Earth and the sun. The picture is of a solar eclipse.
In general language, you eclipse someone if you do something so much better or more obviously than they do that everyone notices you and not them, for example "her beauty eclipsed all others at the dance".
