Earth and Moon

The phases of the moon

The phases of the moon

The moon phases they are the different illuminations that our satellite presents in the course of a lunar cycle or lunar cycle.

Depending on the location of the Moon, the Earth and the Sun, a greater or lesser portion of the visible face of the Moon is illuminated. Although the size of the illuminated area varies continuously, the apparent Moon has been classified throughout history in four stages or Moon phases:

•" The new Moon or novilunio occurs when the Moon is between the Earth and the Sun and, therefore, we do not see it. It is there, but the face that shows us does not receive sunlight from this moon phase.

•" At Growing Room, the Moon, the Earth and the Sun form a right angle, so that half of the Moon in its period of growth can be observed in the sky. The illuminated area is on the right in the northern hemisphere and looks like a D capital letter; In the southern hemisphere the illuminated area is on the left and looks like an inverted C or D.

•" The Full moon or full moon occurs when the Earth is located between the Sun and the Moon; it receives the sun's rays on its visible face, therefore, a complete circle is seen. In this phase the Moon reaches its zenith at midnight.

• »Finally, in the Waning Quarter the three bodies return to form a right angle, so that the other half of the lunar face can be seen in the sky: the left zone illuminated in the northern hemisphere (an inverted C or D) and the right zone in the south ( a D in normal position).

How and when do the phases of the Moon look?

The orbit of the Earth forms an angle of 5º with the orbit of the Moon, so that when the Moon is between the Sun and the Earth, one of its hemispheres, the one we see, is in the dark zone, and by therefore, it is invisible to our sight: we call this a new moon or novilunio.

As the Moon continues its movement of movement, the illuminated surface visible from the Earth grows, passing through the form of concave crescent, until a week later it shows us half of its illuminated hemisphere; This phase is the fourth largest.

Then it continues to grow and acquires the form of a convex or gibbous crescent. A week later we perceive the entire illuminated hemisphere: it is the so-called full moon or full moon. When this full moon passes near the perigee (the point of its orbit closest to Earth), there is a Super moon that seems to look older and brighter than other times.

The following week, the illuminated surface begins to decrease, passing through the shape of a dwindling convex or gibbous moon, until it reaches half illuminated, but, this time, on the other side: it is the waning room.

It continues to decrease, goes through the form of concave waning and we see less and less. At the end of the fourth week it reaches its initial position as a new moon and disappears from our sight. All phases of the Moon have been completed and a new cycle of mooning begins again

The following table shows the 4 phases of the Moon and its intermediate phases:

First nameVisible (*)When do you see it?
New Moon0-2%It doesn't look invisible
Concave crescent3-34%In the afternoon and shortly after sunset
Growing room35-65%In the afternoon and in the first half of the night
Crescent convex66-96%In the afternoon, much of the night
Full moon97-100%All night
Waning convex 96-66%Much of the night, beginning of the morning
Waning Quarter65-35%Early morning and morning
Concave waning34-3%End of the morning and morning

* The crescent moon is illuminated on the right in the northern hemisphere and on the left in the southern hemisphere. The waning, upside down.

Throughout its journey the Moon seems to wobble. This apparent wobble is known as hover.

The synodic month and the sidereal month are not equal

A complete lunar cycle lasts about 29 and a half days, and is called lunation or synodic month. However, an orbit of the Moon around the Earth (a sidereal month) lasts only 27 days and a third. How do you explain this difference?

To understand it, it must be borne in mind that, while the Moon revolves around the Earth, the planet is not still, but rather moves around the Sun and, with it, the Moon. As the phases of the Moon are determined by the relative position of the three stars, our satellite has to take something more than one turn each time to be in the same relative position between the Earth and the Sun, that is, in the same phase lunar.

From time to time the Sun, the Moon and the Earth are located forming a straight line, and eclipses occur. This is what the next page is about.

◄ PreviousNext ►
Moon movementsEclipses