I’m always surprised by the number of people who don’t know how the phases of Moon “work”.
I think a picture really helps visualize the physical reality that underlies what we see from the surface of the Earth. It would be almost impossible to explain Moon phases without pictures (or waving your hands around).
Both the Earth and the Moon are half lit on the side facing the Sun. The Earth rotates once every 24 hours and the Moon orbits the Earth every 28 days. The Earth only faces the Moon 12 hours a day so we get 28 distinct moon phases. Keep in mind that the same side of the Moon always faces the Earth, like it was on a string.
In addition to Moon phases you can also learn from the graphic that:
- There is always a dark side of the Moon, as there is always a dark side of the Earth.
- There is a side of the Moon we never see, but it’s not always dark.
- How eclipses happen. A solar eclipse is the Moon’s shadow on the Earth and a lunar eclipse is the Earth’s shadow on the Moon.
- The half Moons look the same from this viewpoint but from Earth are opposite.
Bonus question: What does the Earth look like from the Moon. Does it have phases?

If you search for images of Moon phases you find way better graphics than I could ever make, but the purpose was to create an educational graphic, so I used GIMP and started from nothing. My goal was to create an interpretive graphic representing a point of view we never get to experience. From this viewpoint in space the Moon phases are much easier to understand.