Phases of the Moon. Composite image showing the Moon at each stage of its 28 day cycle (a lunar month). Along the top row, the Moon is a waxing (growing in apparent size) crescent, reaching a half Moon after 7 days. For the next seven days it is a waxing gibbous (between half and full), reaching a full Moon (far right of second row) after 14 days. The Moon is then a waning (decreasing in apparent size) gibbous, reaching another half moon 21 days into the cycle. On the bottom row it is a waning crescent, reaching the new Moon stage at bottom right. The phases of the Moon are due to it revealing differing amounts of its sunlit face as it orbits the Earth.