That part of the Moon’s shadow that extends beyond the A complete shadow (as of the Moon or the Earth) within which the source of light (the Sun) is totally hidden from view. Also, the dark inner area of a sunspot. More. An A solar eclipse that occurs when the apparent size of the Moon is not large enough to completely cover the Sun. A thin ring of very bright sunlight remains around the black disk of the Moon. More is seen by an observer in the antumbra.