For man, the Moon in the sky is a commonplace phenomenon. However, many do not fully understand why the Earth’s satellite at different periods of time does not look the same. There are people who do not understand, because of which, on some days it is visible in the evening, on others in the morning. And why on the new moon (see photo below) it is not visible at all. To understand the essence of the phase change, it is enough to mentally or using improvised means a model of a section of our star system. The diagram should include: Sun, Earth and Moon. Knowing the direction of their movement, you can easily understand everything.
Moon
There are several theories of the origin of the satellite of our planet. One by one, the Moon and the Earth were “born” as two different planets from a common dust cloud. The smaller of the two fell into the field of attraction of the larger, and their orbits were balanced. According to another theory, everything happened after the collision of the Earth with another large celestial body. This could have happened over 4 billion years ago. The debris of two planets remaining in orbit eventually formed the moon.
The Earth rotates around its axis and the Sun in a counterclockwise direction. The moon orbits in the same direction. If the Earth revolves around the luminary in 365 days, then its satellite around the planet - in 29.5 days. This move is usually divided into four (7.4 days) periods.
From Earth, people can see the moon only when it is lit by sunlight. At the beginning of the cycle for several days, the Earth’s satellite is generally invisible in the sky - the new moon. What is the first and last quarter, the full moon, and why they are so called, it is easier to understand on the layout of a portion of the solar system.
Phases
The beginning of the cycle is considered to be the period when the Earth, the Moon and the Sun line up on the same conditional line in exactly this sequence. It is known that all spherical bodies are only half-illuminated by a light source. What happens on the new moon? The sun illuminates the far side of the Earth from its satellite. That is why people from the surface of the planet do not see it. It hangs overhead, but it is imperceptible in the sky - its half visible to the observer is not lit.
When the satellite, moving in orbit, moves to the left, part of the illuminated surface will become noticeable (first quarter). Crescent Moon will grow a little over a week. In the next same period, the visible (illuminated) part of the satellite will increase. By the fifteenth day, it will reach a maximum and will be a complete circle - the full moon. This orbit point is half the cycle, it is as important as the new moon. What is a decreasing month?
In the next week, the visible part will be reduced. The moon will go three quarters of the distance of the orbit and will be located in relation to our planet on the right. In this period (last quarter), only half of the illuminated disk will be visible again. The last week the moon is waning. Every day her sickle is getting smaller. Two days before the confrontation with the Earth, the illuminated area is practically not visible in the sky. At this point, the cycle ends and everything repeats again.
When the year is new moon, you can find out from the calendar. Usually for each month there is one such period. For some nationalities, the reckoning begins with the new moon. In such countries, it is still customary to start the year not only according to the official calendar.
New moon: what is a growing and aging month
The plane of rotation of the Earth and the Moon do not coincide. If that were the case, then at every new moon there would be a solar eclipse. In fact, in the year of such moments (when the satellite closes the light from people), only a few - 2-5 times. Even less (0–3) lunar eclipses - this is when the shadow of the planet closes its satellite from sunlight.
You can distinguish a rising moon from a waning moon by its visible arc. If the sickle has the form of the correct (not inverse) letter “C”, then this is an aging month. If on the contrary, the light arc resembles the radius of the letter "P" (you can conditionally add a vertical stick), then this is a growing moon. She can always be seen in the evening. And vice versa, the aging Month is visible in the sky in the morning.
Sometimes in clear weather during the day you can see the dull disk of the earth's satellite. Such an “ashy” month can be observed a couple of days before and after a new moon. It has this appearance in the reflections of reflected light. The sun's rays fall on the Earth, are reflected from the atmosphere and slightly illuminate the lunar disk. This period lasts only a few days.
