"As the moon revolves to complete its 27.3 days around the earth, we visualise it going through different phases. However, from the perspective of the sun, the moon’s phase never changes as it is always seen as half illuminated. Here are the eight phases of the moon"
Moon phases are so common in our lives that the mundane beings fail to contemplate about its relevance successfully. What causes the moon to undergo its phases? Is it all because of the earth’s shadow being cast upon the moon? Science says that the phases of the moon boil down to the only fact of its position regarding the earth and sun.
As the moon revolves to complete its 27.3 days around the earth, we visualise it going through different phases. However, from the perspective of the sun, the moon’s phase never changes as it is always seen as half illuminated. Here are the eight phases of the moon:
New moon signifies the start of a new moon cycle and is identified by the absence of the moon in the sky. What we perceive as darkness is only the unilluminated side of the moon when the earth, the sun and the moon are lined up perfectly. Since the illuminated side of the moon is facing the sun, we perceive the absence of light as the absence of the moon.
Waxing phases of the moon refer to the stages when the sun’s light starts illuminating the side of the moon as the cycle proceeds. The waxing phases last until it reaches the full moon phase.
Since the moon proceeds eastward to the sky, we see a crescent of it illuminated. As the cycle proceeds, the moon reaches its first quarter phase that could be identified by its one-fourth completion of the cycle. From the southern hemisphere, you should be able to see this on the left side of the moon and see the alternate side from the northern hemisphere. As the cycle proceeds, the moon reaches its waxing gibbous phase when more of the moon is illuminated than being darkened.
The full moon is the peak of the cycle when we see the entire moon as illuminated. During this phase, the moon rises almost at the same time when the sun sets in the evening sky.
Contrary to the waxing phases, during these phases, the moon starts getting less and less illuminated as nights go by until the cycle reaches the new moon phase.
The waning phases start with the waning gibbous when more of the moon is illuminated. However, the illuminated side gets more and more darkened as nights go by. The third quarter signifies the half-lit moon that appears on the right side of the moon in the southern hemisphere. The waning crescent is the last stage in the phases of the moon, which is denoted by a sliver of the illuminated side fading away.
Our alma mater has stressed enough on the fact that the moon does not illuminate itself but reflects the sun’s light. Since our satellite is tidally fixed we are only able to see the same side of the moon in each phase. As the moon revolves around the earth, the sun keeps lighting it, which is why the darkness increases and diminishes with the different phases of the moon.