Umbra and Penumbra

The shadow that the Moon casts upon the Earth has two regions.



Umbra

The main part of the shadow, which is directly in line with the Sun, is called the Umbra. This is the point where all light from the Sun is blocked out. Viewed from the Earth a person in the umbra would observe a Total Eclipse .

Penumbra

The other region of shadow is called the Penumbra and viewed from the Earth a person here would observe a Partial Eclipse . The shadow this casts is not as dark as the Umbra and so it only blocks out some of the sunlight.


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