Caption: Earth's umbra and penumbra as caused by the Sun.

Features:

1. Umbra: This is a cone of shadow narrowing away from the Earth. In the umbra, NO part of the Sun can be seen by straight line light ray transmission.

   To be a bit more precise, NO part of the solar photosphere (which is the layer from which most light escapes from the Sun) can be seen by straight line light ray transmission.

   We discuss the solar photosphere in IAL 8: The Sun.

   As we discuss IAL 3: The Moon: Orbit, Phases, Eclipses, and More: The Coppery Colored Moon, there is some curved-line light ray transmission due to atmospheric refraction, and so the umbra will NOT be totally dark.

2. Penumbra: This is a cone of shadow widening away from the Earth. In the penumbra, a crescent of the Sun can be seen.

3. Both umbra and penumbra stretch away from the Earth in the anti-solar direction.

4. See Eclipse keywords below (local link / general link: eclipse_keywords.html):

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