Image:Gibbous-Crescent-half-ellipse-in-circle.svg - Simple English Wikipedia, the free encyclopedia

# Image:Gibbous-Crescent-half-ellipse-in-circle.svg

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Gibbous-Crescent-half-ellipse-in-circle.svg‎ (612 × 612 pixel, file size: 672 B, MIME type: image/svg+xml)

This is a file from the Wikimedia Commons, a repository of free content hosted by the Wikimedia Foundation. The description on its description page there and licensing information is visible below.

## [edit] Summary

A circle divided into a gibbous shape (red) and an astronomical crescent shape (blue) by a half-ellipse, where the major axis of the ellipse coincides with a diameter of the circle. According to geometry, an illuminated hemisphere of a sphere will appear to take on such gibbous or crescent shapes when viewed from an angle. In this case, the length of the major axis of the ellipse is twice the length of the minor axis (i.e. the eccentricity is half the square root of 3), so that the red gibbous area shows the theoretical shape of the visible lit area of the moon (for example) when the separation between the viewing angle and the angle of illumination (i.e. between Earth and Sun) is 60 degrees, while the blue crescent area shows the theoretical shape of the visible lit area of a sphere when the separation between the viewing angle and the angle of illumination is 120 degrees. See also Image:Gibbous-Crescent-half-ellipse-in-circle-outlined.svg

SVG version of Image:Gibbous-Crescent-half-ellipse-in-circle.png

Converted from the following PostScript code:

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    .75 0 0 setrgbcolor
    306 396 144 0 360 arc
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    0 .2 .85 setrgbcolor
    306 396 144 90 -90 arcn
    39.765 0 72 64.471 72 144 rcurveto
    0 79.529 -32.235 144 -72 144 rcurveto
    closepath
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    %%EOF

## [edit] Licensing

| This image has been released into the public domain by its author, AnonMoos. This applies worldwide. In some countries this may not be legally possible; if so: AnonMoos grants anyone the right to use this work for any purpose, without any conditions, unless such conditions are required by law.

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## Links

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- Crescent

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