Phases of the moon

This astronomy diagram sample was redesignrd from the Wikimedia Commons file: Phases of the moon.gif. [commons.wikimedia.org/ wiki/ File:Phases_ of_ the_ moon.gif]
This file is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported license. [creativecommons.org/ licenses/ by-sa/ 3.0/ deed.en]
"The lunar phase or phase of the moon is the shape of the illuminated (sunlit) portion of the Moon as seen by an observer, usually on Earth. The lunar phases change cyclically as the Moon orbits the Earth, according to the changing relative positions of the Earth, Moon, and Sun. The moon and the Earth are tidally locked, and therefore the same lunar surface always faces Earth. This face is variously sunlit depending on the position of the moon in its orbit. Ergo, the portion of this hemisphere that is visible to an observer on Earth can vary from about 100% (full moon) to 0% (new moon). The lunar terminator is the boundary between the illuminated and darkened hemispheres. Aside from some craters near the lunar poles such as Shoemaker, all parts of the Moon see around 14.77 days of sunlight followed by 14.77 days of "night" (the "dark side" of the Moon is a reference to radio darkness, not visible light darkness).
The four principal lunar phases are first quarter, full moon, third quarter, and new moon (third quarter moon is also known as last quarter moon.) Each of the four lunar phases is roughly 7 days (~7.4 days) each, but varies slightly due to lunar apogee and perigee." [Lunar phase. Wikipedia]
The astronomical diagram example "Phases of the moon" was created using the ConceptDraw PRO diagramming and vector drawing software extended with the Astronomy solution from the Science and Education area of ConceptDraw Solution Park.