The spectacle of the Moon passing through the Earth’s shadow is not as simple as you might expect, however.  Rather than simply passing into the darkness to vanish for a while, before re-emerging into the light, we see quite a complex sequence of events.  This is because the Earth’s shadow is composed of two regions:  The penumbra and the umbra.  The umbra is the fully dark part of the shadow, and is shown in the diagram above as the dark … Continue reading →