Phases of the Moon

In short: The Moon does not shine by itself but reflects sunlight. Because it orbits the Earth, over a month we see different portions of its lit half.

In more detail: One cycle from new moon to new moon lasts about 29.5 days (synodic month).

In detail

• New moon: The Moon is between Earth and Sun; the side facing us is dark.
• Waxing moon: Lit on the right (in the northern hemisphere). Mnemonic: the shape of the waxing moon resembles a “D” (“Dividing” up).
• Full moon: The Earth is between Sun and Moon; the whole disc shines.
• Waning moon: Lit on the left, the shape of a “C”.
• Tidal locking: The Moon always shows us the same face (gezeiten-ebbe-und-flut, sonnenfinsternis-und-mondfinsternis).