A28: A total penumbral eclipse is a lunar eclipse occurs when the moon becomes completely immersed in the penumbral cone of the Earth without touching the umbra.
It is a narrow path for the moon to pass within the peumbral and outside the umbra. It can happen on the Earth's northern or southern penumbral edges. In addition size of the penumbral is sometimes too small to contain the moon. Its width is equal to the angular diameter of the sun at the time of the eclipse, and the moon's angular diameter is larger than the sun over part of its elliptical orbit, depending on whether the eclipse occurs at its nearest (perigee) or farthest point (apogee) in its orbit around the earth.