This post has been corrected. Please see note at bottom for details.
Sky watchers, it is time to look up once again, and watch the moon very, very carefully. A penumbral lunar eclipse will occur early Wednesday morning, but it will be subtle.
Unlike a total lunar eclipse, when the moon passes behind the dark center of the earth's shadow, a penumbral lunar eclipse occurs when the moon passes through the hazy outer edge of the earth's shadow, called the penumbra.
During a penumbral eclipse, the moon doesn't so much black out completely as darken subtly, but noticeably, if you are paying attention.