How moon phases work
The Moon does not change shape. You see a different part of its illuminated half.
Sun, Earth and Moon
First quarter
50.0% illuminated • waxing
This is how the Moon looks from Earth at this position.
The four major phases
- New moon — The Moon is between Earth and the Sun; the side facing us is unlit.
- First quarter — A quarter of the orbit has passed: exactly half is lit and the Moon is waxing.
- Full moon — Earth is between the Sun and Moon; we see the entire illuminated side.
- Last quarter — Half is lit again, but now the light is waning.
Waxing and waning
Between new and full moon, the lit portion grows: the Moon is waxing. Between full and new moon, it shrinks: the Moon is waning. In the Northern Hemisphere, a waxing Moon is illuminated on the right.
The synodic month
A full cycle from new moon to new moon lasts on average 29.53059 days. Because the Moon's orbit is elliptical, the actual length varies from cycle to cycle. Mooncalendar calculates each event separately instead of using an average.
Astronomy, not astrology
Mooncalendar shows calculated positions and times. It makes no claims about effects on people, events or personality.