Gibbous-Crescent-half-ellipse-in-circle.svg
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Summary
| Description | A circle divided into a gibbous shape (light grey) and an astronomical crescent shape (dark grey) 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 light grey 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 dark grey 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. |
| Source | Own work based on: Gibbous-Crescent-half-ellipse-in-circle.png |
| Author | AnonMoos |
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Converted from the following PostScript code:
%! .75 0 0 setrgbcolor 306 396 144 0 360 arc fill 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 fill showpage %EOF
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AnonMoos
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