The phases of the moon are caused by the position of the moon in relation to the sun. Half of the moon is always illuminated by the sun, but we perceive different phases based on the moons position in relation to us. When the dark portion of the moon is the half that is turned away from the sun, we see a portion of the moon shadowed and invisible. The key phases of the moon include:

• New Moon: This phase happens when the sun, moon, and earth are located in a straight line, with the moon between the sun and the earth. The side of the moon that we see is in total darkness.

• Waxing Crescent Moon: As the moon moves around the earth in its orbit, the light reflecting off the side of the moon creates a sliver of shape. This is a crescent moon, and it appears to grow fatter each night.

• First Quarter Moon: When half of the moons disc is illuminated, we call it the first quarter moon. The moon is now one-quarter of the way through the lunar month.

• Waxing Gibbous Moon: Once more than half of the disc is illuminated, it has a shape we call gibbous. The gibbous moon appears to grow fatter each night until we see the full sunlit face of the moon.

• Full Moon: The moon is said to be in full phase when the illuminated half of the moon is fully in position for us to see it. This occurs during the time when the earth, moon, and sun are located in a relatively straight line with the earth between the moon and the sun.

• Waning Gibbous Moon: During the second half of the lunar month, the moon grows thinner each night. Its shape is still gibbous at this point, but grows a little thinner each night.

• Third Quarter Moon: When the moon shows us one side of its disc illuminated and the other side in darkness, we call it the third quarter moon. The moon is now three-quarters of the way through the cycle, as measured from one new moon to the next.

• Waning Crescent Moon: As the moon continues to orbit, it appears to get smaller and thinner each night. This is called waning, and its shape is still crescent at this point.

It is important to note that there is no official "half moon" phase, at least not in any official way recognized by astronomers. When referring to a half moon, observers are usually looking at a quarter moon.