The eight faces of the Moon
Half of the Moon is always lit by the Sun. How much of that lit half faces us depends on where the Moon is in its orbit. Select a phase, or drag the slider below, to see what it looks like from Earth and why.
Full Moon
100% illuminated · Day 14.8
The whole near side is bright. Around full Moon the far side is the hemisphere turned away from the Sun, so it is the half in darkness.
Why it happensEarth lies between the Sun and the Moon, so the whole sunlit hemisphere faces us. A full Moon rises at sunset because it is opposite the Sun in the sky.
Rises at sunset, highest at midnight, sets at sunrise.
One lunar month · 29.5 days
Northern-hemisphere viewEarth, the Moon, and the sunlight in between
The Sun lights exactly half of the Moon at every point in its orbit. What changes is how much of that lit half is turned toward Earth.
Full Moon
100% illuminated · Day 14.8
How the Moon's orbit and sunlight create the phases
Half the Moon is always lit
The Sun lights exactly half of the Moon at any moment. Phases are not caused by Earth's shadow — that only happens during a lunar eclipse. What changes is how much of that sunlit half is turned toward us.
The orbit decides what we see
The Moon completes an orbit around Earth every 27.3 days (a sidereal month), but the Sun–Earth–Moon angle repeats only every 29.5 days (a synodic month) because Earth is also moving around the Sun. That extra 2.2 days is why the phases slowly drift through the calendar.
The terminator tells the story
The line between day and night on the Moon is called the terminator. Along it, the Sun sits on the lunar horizon, so shadows there are extremely long — which is why the best time to view lunar mountains and craters through a telescope is near a quarter phase, not at full Moon.
The far side is not the dark side
The Moon rotates once for every orbit it makes, so the same hemisphere always faces Earth and the other always faces away — the far side. It is not permanently dark: it receives just as much sunlight as the near side, simply turned away from us. Over time a gentle wobble called libration lets us see around the edges, so about 59% of the surface becomes visible from Earth.
These illustrations show the Moon as seen from the northern hemisphere, where a waxing Moon is lit on the right. The phases themselves are the same for every observer on Earth at the same moment — south of the equator the sequence appears mirrored, and near the equator the lit limb is tipped almost horizontal. Illumination percentages describe the fraction of the visible disc that is lit, not the Moon's distance or brightness.