STAGE 3

Moon enters umbra

The Moon now begins to cross into the Earth's dark central shadow, called the umbra. A small dark scallop begins to appear on the Moon’s left-hand (eastern) limb. The partial phases of the eclipse begin; the pace quickens and the change is dramatic.

The umbra is much darker than the penumbra and fairly sharp-edged. As the minutes pass the dark shadow appears to slowly creep across the Moon's face. At first the Moon's limb may seem to vanish completely inside of the umbra, but much later, as it moves in deeper you'll probably notice it glowing dimly orange, red or brown.

Notice also that the edge of the Earth's shadow projected on the Moon is curved. Here is visible evidence that the Earth is a sphere, as deduced by Aristotle from Iunar eclipses he observed in the 4th Century BC. Almost as if a dimmer switch was slowly being turned down, the surrounding landscape and deep shadows of a brilliant moonlit night begin to fade away.

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