Everything about Antumbra totally explained
For other uses of the word "umbra", see Umbra (disambiguation).
For other uses of the word "penumbra", see Penumbra (disambiguation).
The
umbra,
penumbra and
antumbra are the names given to the three distinct parts of a
shadow which are created when the source of light isn't a
point source. These names are usually used when referring to the shadows cast by
celestial bodies.
In reality there's no such thing as a point source
radiator, though in theory such a light source would cast an umbra, but not an antumbra or penumbra.
Umbra
The
umbra (Latin:
shadow) is the darkest part of a
shadow. From within the umbra, the source of
light is completely concealed by the
occulting body. In
astronomy, an observer in the umbra is said to be experiencing a
total eclipse.
Penumbra
The
penumbra (Latin:
paenes "almost, nearly" +
umbra "shadow") the region in which only a portion of the occulting body is obscuring the light source. An observer in the penumbra experiences a
partial eclipse.
Antumbra
The
antumbra is the region from which the occulting body appears entirely contained within the disc of the light source. If an observer in the antumbra moves closer to the light source, the apparent size of the occulting body increases until it causes a full umbra. An observer in this region experiences an
annular eclipse.
Further Information
Get more info on 'Antumbra'.
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