moonutumisena

Moonutumisena is a term that refers to the observable changes in the Moon's appearance over approximately a month. These changes are not due to the Moon itself producing light, but rather to the varying amounts of sunlight that illuminate it as it orbits the Earth. The cycle of moonutumisena is known as the lunar cycle or synodic period.

The cycle begins with the New Moon, when the Moon is positioned between the Earth and the Sun, making its illuminated side invisible to us. As the Moon moves in its orbit, a sliver of its illuminated surface becomes visible, marking the waxing crescent phase. This is followed by the First Quarter, where half of the Moon appears lit. The waxing gibbous phase sees more than half of the Moon illuminated. The Full Moon occurs when the Earth is between the Sun and the Moon, with the entire face of the Moon visible and brightly lit.

After the Full Moon, the illuminated portion begins to decrease. This is the waning gibbous phase, followed by the Last Quarter, where again, half of the Moon is lit. The waning crescent phase shows a shrinking sliver of light before returning to the New Moon, completing the cycle. The duration of one complete moonutumisena cycle is about 29.5 days. These phases are a fundamental aspect of observing the night sky and have been a subject of human fascination and measurement for millennia.