In our solar system, the light from the sun falls on all the planets
and their moons. Each of these casts its shadow in the direction
opposite to the source of light - the sun. Where does this shadow
fall ? Usually into space. Sometimes the shadow of one of these
planets or moons falls on an other planet or moon. If we view the
sun at this time from this location, the sun is partially or fully
covered. This we call as an eclipse. We have many eclipses in our
solar system- that of the sun, the moon and the satellites of jupitor.
For example, when
the moon passes in front of the sun, the shadow sometimes falls
on the earth's surface. And if we view the sun from this shadowed
location, the moon covers the sun's disc. This is what a solar eclipse
is - and in fact it is nothing but a shadow.