The upper part of the diagram is not to scale, as the Moon, the Earth, and the Moon's orbit are all much smaller relative to the Earth's orbit than shown here. Each phase would be rotated 180° if seen looking northward from the Southern Hemisphere. The phases of the Moon as viewed looking southward from the Northern Hemisphere.

The visible side of the Moon is sunlit to varying extents, depending on the position of the Moon in its orbit, with the sunlit portion varying from 0% (at new moon) to nearly 100% (at full moon). The appearance of the Moon (its phase) gradually changes over a lunar month as the relative orbital positions of the Moon around Earth, and Earth around the Sun, shift. A lunar month is the time between successive recurrences of the same phase: due to the eccentricity of the Moon's orbit, this duration is not perfectly constant but averages about 29.5 days. In common usage, the four major phases are the new moon, the first quarter, the full moon and the last quarter the four minor phases are waxing crescent, waxing gibbous, waning gibbous, and waning crescent. Shape of the Moon's sunlit portion as viewed from Earth The lunar phases and librations in 2023 as viewed from the Northern Hemisphere at hourly intervals, with titles and supplemental graphics The lunar phases and librations in 2023 as viewed from the Southern Hemisphere at hourly intervals, with titles and supplemental graphics A full moon sets behind San Gorgonio Mountain in California on a midsummer's morning.Ī lunar phase or Moon phase is the apparent shape of the Moon's directly sunlit portion as viewed from the Earth (because the Moon is tidally locked with the Earth, the same hemisphere is always facing the Earth).

Moon phases ten