Late Sunday night, or more precisely in wee hours of Monday the brilliant full moon, the Mud Moon, is going to dim. The moon will drop in brightness beginning after midnight. The dimmest moment will be at 3:13 a.m. and the eclipse will end at 5:30 a.m.

This is not a big deal, because the moon's brightness will only drop slightly, not significantly. This is a penumbral eclipse. The Earth casts two shadows. The central part of the shadow is called the umbra. The outer shadow is called the penumbra. The penumbral eclipse, in the earliest hours of Monday morning is interesting to those who are used to seeing a brilliant shining moon. The moon will still be up there, easy to find, but dimmer.

If you were standing on the moon during an umbra eclipse, the Sun would disappear from your view, blocked completely by the Earth . If you were standing on the moon during a penumbral eclipse, you'd notice that the earth was only blocking a small portion of your view of the blazing sun. We'll all get a similar taste of that view on the Vineyard when we see only a piece of a daytime solar eclipse on April 8.

The most visual aspect of the show is the moon's brilliance. This is not the umbra lunar eclipse when the moon darkens to the color of an orange pumpkin and is hard to spot in the sky. With this eclipse, the moon looks like someone turned down the light.