As the Moon is at a very moderate distance from us (astronomically
speaking), and is in fact our nearest neighbour, while the sun and
stars are in comparison immensely beyond it, it must of necessity
happen that at one time or other it must _pass over_, and _occult_ or
_eclipse_, every star or planet within its zone, and, as seen from
the _surface_ of the earth, even somewhat beyond it. Nor is the sun
itself exempt from being thus hidden whenever any part of the moon’s
disc, in this her tortuous course, comes to _overlap_ any part of the
space occupied in the heavens by that luminary. On these occasions
is exhibited the most striking and impressive of all the occasional
phenomena of astronomy, an _Eclipse of the Sun_, in which a greater or
less portion, or even in some conjunctures the whole of its disc, is
obscured, and, as it were, obliterated, by the superposition of that
of the moon, which appears upon it as a circularly-terminated black
spot, producing a temporary diminution of daylight, or even nocturnal
darkness, so that the stars appear as if at midnight.--_Sir John
Herschel’s Outlines._