New Moon
The Moon is between Earth and the Sun. The side facing us is entirely in shadow, so the Moon is not visible. Illumination: 0 %.
How the Moon appears from Earth as it orbits
The Moon is between Earth and the Sun. The side facing us is entirely in shadow, so the Moon is not visible. Illumination: 0 %.
A thin sliver of the Moon is lit on the right side. "Waxing" means the lit area is growing each night. Visible in the western sky after sunset.
Exactly half of the Moon's disk is lit (the right half). The Moon has completed one quarter of its orbit. Illumination: 50 %. Rises around noon, sets around midnight.
More than half is lit, but not yet full. The right side is bright with only a thin dark crescent remaining on the left. Still growing toward Full Moon.
Earth is between the Sun and the Moon. The entire sunlit side faces us, so we see a complete bright disk. Illumination: 100 %. Rises at sunset and sets at sunrise.
More than half is still lit, but the illuminated area is now shrinking. The left side is bright with a thin dark crescent growing on the right.
Exactly half of the disk is lit (the left half). The Moon has completed three quarters of its orbit. Illumination: 50 %. Rises around midnight, sets around noon.
A thin sliver is lit on the left side. The last visible phase before the next New Moon. Often seen in the eastern sky before sunrise.
The Moon does not make its own light; we see it by sunlight. As the Moon orbits Earth (about once a month), the angle between the Sun, Earth, and Moon changes. We always see the same "face" of the Moon, but how much of that face is lit by the Sun determines the phase.