Of or relating to a → penumbra.
penumbral lunar eclipse
Fr.: éclipse de lune pénombrale
A lunar eclipse that occurs when the Moon passes through the Earth's → penumbra, but misses the darker umbral shadow. Because the Moon is only partially dimmed, a penumbral eclipse is not impressive. Total penumbral eclipses are rare, and when these occur, that portion of the Moon which is closest to the umbra can appear somewhat darker than the rest of the Moon.