Understanding The Moon Phases
Have you ever wondered what causes the moon phases? We all know that its appearance changes over time. But why? The good way to understand the phases of the moon is to examine an earth-moon-sun diagram:
PHASES OF THE MOON
The revolution of the Moon around the Earth causes the Moon to appear to change shape in the sky. These different shapes are called "phases" of the moon. The Moon passes through a cycle of eight phases every 29.5 days. There is no definite starting point for the cycle, but phases follow one behind the other in a strict order. You will find images of each of the eight phases, as well as a breif description of each phase. The images reflect the order the phases are viewed from the earth.
Waxing Crescent
The visible moon is partly but less than one-half illuminated by direct sunlight while the illuminated part is increasing.
First Quarter
One-half of the moon appears illuminated by direct sunlight while the illuminated part is increasing
Waxing Gibbous
The Moon is less than fully illuminated but greater than half illuminatedby direct sunlight while the illuminated part is increasing
Full Moon
The visible moon is fully illuminated by direct sunlight.
Waning Gibbous
The Moon is less than fully illuminated but greater than half illuminatedby direct sunlight while the illuminated part is decreasing
Last Quarter
One-half of the moon appears illuminated by direct sunlight while the illuminated part is decreasing
Waning Crescent
The visible moon is partly but less than one-half illuminated by direct sunlight while the illuminated part is decreasing.
New Moon
The visible moon is not fully illuminated by direct sunlight.
