During phases 5 through 8, the amount of light area decreases (or the darkened area increases) from right to left. When this occurs, the Moon is said to be waning. Therefore you can tell if the Moon is waxing or waning based on whether the right side of the Moon is dark or light.

There’s no half-moon phase, at least not in any official way. Invariably, when referring to a half moon, observers are looking at a quarter moon. You see a moon that looks half-illuminated, like half a pie. Full moon signifies that the full visible surface of the moon – its day side – is fully turned toward Earth.

It is all a result of the Moon’s orbit around the Earth, and the Earth’s orbit around the Sun. And exactly when you see the Moon in the shape of a ‘U’ (lit on the bottom) rather than a backward ‘C’ (lit on the side) depends on what latitude you are at. So the lit part of the Moon always points toward the Sun.

Because the waxing crescent moon is nearly on a line with Earth and the sun, its illuminated hemisphere – or day side – is facing mostly away from us. We see only a slender fraction of the day side: a crescent moon.

WANING CRESCENT Just like the waning gibbous phase, the illuminated portion of the Moon is decreasing towards the New Moon. In the waning crescent phase, we see only a sliver of the illuminated Moon.

The last quarter moon (or a half moon) is when half of the lit portion of the Moon is visible after the waning gibbous phase. A waning crescent moon is when the Moon looks like a crescent and the crescent decreases (“wanes”) in size from one day to the next.

Full moon, mood, and mental health This has led to the development of circadian rhythms that affect many of your body’s systems — not just your sleep-wake cycle. When circadian rhythms wobble, it can cause or increase symptoms of certain mental health disorders, including: anxiety. bipolar disorder.