According to folklore, this Friday's full moon is the Harvest Moon--a bright orb that shines down on the ripening fields of the northern hemisphere, allowing farmers to harvest their crops late into the night. The Harvest Moon of Sept. 16th won't be as bright as usual, though. It's going to pass through Earth's shadow, producing a penumbral lunar eclipse.

Penumbral eclipse of the Moon
© Shadow and SubstanceThis is a penumbral eclipse of the Moon that is centered south of India. For us in the United States, we will not see it. This eclipse is interesting, because it appears like a cloud is shading the northern portion of the Moon. If you were on the Moon, looking back towards Earth, the Sun would appear partially eclipsed. If you are in the eastern hemisphere, try looking for it. (Information derived from USNO.)
A penumbral eclipse happens when the Moon passes through the pale outskirts of Earth's shadow. It is much less dramatic than a total lunar eclipse. In fact, when observers are not alerted beforehand, they often do not realize an eclipse is underway. Nevertheless, the subtle shadow of Earth is visible to the naked eye if you know it's there.

Larry Koehn of ShadowandSubstance.com has created an excellent animation of the event (see video below).

The eclipse will not be visible in the Americas. Observers there can enjoy the Harvest moonlight, undimmed, while watching the eclipse unfold elsewhere in the realtime photo gallery.