umbra

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umbra

um·bra

 (ŭm′brə)
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.
2. Astronomy
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.

[Latin, shadow.]

um′bral adj.

umbra

(ˈʌmbrə)
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]
ˈumbral adj

um•bra

(ˈʌm brə)

n., pl. -bras, -brae (-brē).
1. shade; shadow.
2. the usual accompaniment or companion of a person or thing.
3. Astron.
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]
um′bral, adj.

um·bra

(ŭm′brə)
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.
ThesaurusAntonymsRelated WordsSynonymsLegend:
Noun1.umbra - a region of complete shadow resulting from total obstruction of lightumbra - a region of complete shadow resulting from total obstruction of light
shadow - shade within clear boundaries

umbra

noun
Comparative darkness that results from the blocking of light rays:
Translations

umbra

n pl <-s or -e> (Astron: = shadow) → Kernschatten m; (in sunspot) → Umbra f
References in periodicals archive ?
Observers have been asked on some occasions to use the steepest brightness gradient in the umbra's edge for making their timings (our preferred method), and at other times to use the mid-brightness between the umbra and penumbra on either side of the edge.
These proceed from the z-coordinate of the vertices of the lunar umbra and penumbra.
The researchers conclude that there is a unified physical explanation for the structure of sunspots in umbra and penumbra that's the consequence of convection in a magnetic field with varying properties.