Waning
Origin
Middle English, from Old English wanian; akin to Old High German wanōn to wane, Old English wan wanting, deficient, Latin vanus empty, vain
Definitions
- 1: to decrease in size, extent, or degree : dwindle: as a : to diminish in phase or intensity —used chiefly of the moon, other satellites, and inferior planets
2: to fall gradually from power, prosperity, or influence
Description
A lunar phase or phase of the moon is the appearance of the illuminated (lighted) 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. One half of the lunar surface is always illuminated by the Sun (except during lunar eclipses), and hence is bright, but the portion of the illuminated hemisphere that is visible to an observer can vary from 100% (full moon) to 0% (new moon). The boundary between the illuminated and unilluminated hemispheres is called the terminator.[1]
