lunar phases
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The apparent shapes of the Moon as seen from the Earth, which are caused by the Moon's orbit of the Earth once every 29.5 days. The same phase will fall on the same date of the year according to the Saros cycle, every 18 years, 11 days, and eight hours. The phases of the Moon are:
New Moon
In conjunction with the Sun; rises and sets with it. Zero percent illuminated, 0 degrees elongation.
Waxing Crescent
Prominent just after sunset; less than 50 percent illumination.
First Quarter
Rises at noon and sets at midnight; 50 percent illuminated, 90 degrees east elongation.
Waxing Gibbous
Lunar illumination increasing between first quarter and full.
Full Moon
In opposition with the Sun; rises at sunset and sets at sunrise; 100 percent illuminated, 180 degrees elongation.
Waning Gibbous
Decreasing illumination decreasing between full and last quarter.
Last Quarter
Rises at midnight and sets at noon; 50 percent illuminated, 90 degrees west elongation.
Waning Crescent
Prominent just before sunrise; less than 50 percent illumination.