Everyone knows that when looking at the Moon at night, depending on the phase in which it is, we are going to find one image or another. This is because the movement that our satellite makes with respect to both our planet and the Sun influences the way we can see it and, depending on the form it takes, it will receive one name or another.
Why the Moon has different phases
When talking about the phases of the Moon, it refers to the way we see the Moon from Earth . Because the Moon is in motion with respect to both the Sun and our own planet, this means that the part that illuminates the Sun is not always visible from our perspective. Consequently, from the surface of the Earth we can observe the Moon in different ways, from the total absence of the Moon to the full Moon phase, going through various phases of growth and decrease of the observable light from its surface.
On the other hand, it must be borne in mind that the phases of the Moon have nothing to do with lunar eclipses . Although similar effects can be created, in the case of lunar eclipses, the changes that are seen in the illuminated surface of the Moon are due to the fact that the Earth is interposed between it and the Sun. In the case of lunar phases, the changes observed are also due to the relationship between the Moon, the Earth and the Sun, but they happen cyclically and continuously, not like eclipses, which take place only in exceptional cases. In fact, the lunar phases are a perception that we have from the Earth, since, in reality, on a regular basis, the Moon is always illuminated in 50% of its surface and dark in the other half, as is the case with our planet.
Because the point of view is different from the northern hemisphere and the southern hemisphere, when the Moon is observed, the vision that we are going to obtain in each case will be the opposite to that of the other hemisphere . However, this does not mean that the phase in which the Moon is located is different, but that depending on the hemisphere we are in, they will be observed differently.
One method to quickly find out what phase the Moon is in in the southern hemisphere is to associate the shape of the letter C with the increasing phases, while the letter D is associated with the decreasing ones. In this way, if we look at the Moon in the southern hemisphere and see that the illuminated part forms a C, we can be sure that it is in an increasing phase, while if the illuminated area resembles the arc of the D, it will be a decreasing phase.
On the other hand, although this rule works for the southern hemisphere, in the case of observing the Moon from the northern hemisphere, it will be enough to invert it. That is to say, D will correspond to the increasing phase and C to the decreasing phase.
Phase 1: New Moon
This phase corresponds to a phase in which the Moon is normally impossible to see by looking directly at the sky because it is completely covered by sunlight.
Phase 2: Crescent Moon
It lasts three to four days later than the phase of the new moon. It adopts the characteristic shape of a very thin Moon, narrow and curved at its ends. In the northern hemisphere it is the part on the right that appears illuminated, while in the entire southern hemisphere it will be the left area that appears bright.
Phase 3: First quarter
This phase occurs four days later than the waxing Moon. In this phase, 50% of the Moon is already illuminated , in such a way that it has a straight line that separates the light from the dark zone. In the case of the northern hemisphere that 50% illuminated will correspond to the part on the right, while in the southern hemisphere it will be the other way around.
Phase 4: Crescent gibbous moon
It is defined because it loses the straight line that separates the light and dark areas and takes on the characteristic convex Moon image.
Phase 5: Full Moon
Also called the full moon , it is the phase in which the Moon is fully illuminated and forms a circle. It is important because it is the phase that marks the middle of the lunar month, formed by something a few hours less than fifteen calendar days.
Phase 6: Waning gibbous moon
After the full Moon phase, the Moon will begin its process to wane. It will take the same shape as phase 4 (waxing gibbous moon) but, in this case, the process will evolve towards a larger dark surface.
Phase 7: Last quarter
It corresponds to phase 3 (increasing quarter), although in reverse, since it will be in a decreasing phase. That is, half of the Moon will be observed illuminated and the other half dark, but knowing that the process will evolve towards greater darkness.
Phase 8: Waning Moon
It corresponds to phase 2 (Crescent Moon) and the aspect will be that of a very narrow and curved curved line, and that it approaches total darkness.
Stage 9: Black Moon
It corresponds to the final phase of the Moon visible from the earth’s surface, and will give way to a new cycle with its corresponding lunar phases, which will begin with the new Moon.