umbra(redirected from Umbra and Penumbra)
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n. pl. um·bras or um·brae (-brē)
1. A dark area, especially the blackest part of a shadow from which all light is cut off.
a. The completely dark central portion of the shadow cast by the earth, moon, or other body during an eclipse.
b. The darkest region of a sunspot.
n, pl -brae (-briː) or -bras
1. (Astronomy) a region of complete shadow resulting from the total obstruction of light by an opaque object, esp the shadow cast by the moon onto the earth during a solar eclipse
2. (Astronomy) the darker inner region of a sunspot
[C16: from Latin: shade, shadow]
n., pl. -bras, -brae (-brē).
1. shade; shadow.
2. the usual accompaniment or companion of a person or thing.
a. the complete or perfect shadow of an opaque body, as a planet, where the direct light from the source of illumination is completely cut off.
b. the dark central portion of a sunspot.
4. a phantom or ghost.
[1590–1600; < Latin: shade, shadow]
1. The darkest part of a shadow, especially the completely dark portion of the shadow cast by Earth, the moon, or another body during an eclipse.
2. The darkest region of a sunspot. Compare penumbra.