Why do we see different phases of the moon?

Each month, the Moon goes through its four phases: New Moon, First Quarter, Full Moon and Third Quarter. During Full Moon and New Moon, impressive lunar and solar eclipses can occur.

Into the shadow: A lunar eclipse occurs when the Full Moon passes through the central shadow (the umbra) of the Earth. It can be seen from anywhere on Earth where the moon is above the horizon.
Credit: ESO/M. Kornmesser
In phase: The phases of the Moon result from our changing view of the illuminated portion of its surface.
Credit: ESO

The Moon itself does not generate light; it is lit up by the Sun. As the Moon orbits the Earth, the portion of illuminated Moon that we see changes – giving rise to the phases of the Moon. Starting at the New Moon phase, the Moon appears to expand in illumination. Once it reaches the Full Moon phase, it then seems to decrease in illumination until we reach the New Moon again after one month. Sometimes the Earth, Moon and Sun are aligned such that the Earth is directly between the Sun and the Moon. The Earth casts a shadow onto the Moon, causing a lunar eclipse. When the Moon moves directly between the Earth and the Sun, we see a solar eclipse.

The origin of the word “month” comes from the word Moon. In one whole month we see the full range of phases of the Moon. Can you name the phases?