A brief outline of the Moon's movement
The Moon in the zodiacal constellation
Approximately, this can be done from direct observations, taking the data about the Moon phase from a regular wall calendar (keep in mind that during a new moon, the Moon is "ahead" of the Sun, in the first quarter - 90 degrees to the east of the Sun, at full moon - 180 degrees, and finally, in the last quarter - 90 degrees to the west of the Sun).
One can use a movable star map to approximate the positions of the Moon.
However, the most reliable and accurate way to determine the Moon's position in the celestial sphere is by using astronomical software-planetariums on a personal computer. With such programs, one can determine the position not only of the Moon and the Sun but also of planets, comets, asteroids, and even artificial satellites of the Earth.
To understand how the Moon moves across the celestial sphere, let's trace its path from new moon to the next new moon.
The observed speed of the Moon's movement among the stars is higher than the speed of a similar movement of the Sun. In a day, the Moon covers an angular distance equal to 13.2 degrees, i.e., it shifts by the magnitude of its own angular diameter (30 arc minutes) every hour. The Sun moves among the stars much slower - only 1 degree per day.
The duration of the cycle of changing phases is 29.5 days - synodic month.
During each month, the Moon, moving among the stars in the same direction as the Sun, catches up to our luminary and overtakes it. The moment when the astronomical longitudes of the Moon and the Sun are equal corresponds to the new moon phase, taken as the arbitrary beginning of the Moon's phase cycle. Formally, the period of visibility of the new moon phase falls within daylight hours. It is also evident that this phase is practically unobservable.
After the Moon reaches the position of its closest approach to the Sun, the narrow bright crescent starts to grow.
In the phase of the thin crescent, the Moon appears shortly after sunset and sets near the point of sunset. The convex side of the crescent Moon, facing the Sun, is called the illuminated limb of the visible disc of the Moon. The concave side of the crescent represents the boundary of the shadow on the lunar surface and is called the terminator. The Moon in the phases immediately following the new moon is called the young or waxing crescent.
The ends of the crescent at the intersection of the terminator with the limb are called horns, and the diameter of the visible disc that passes through these points is the horn line.
In astronomical literature, one often encounters the phrase "Moon age," which signifies the period of time elapsed since the last new moon.
A young or waxing Moon remains above the horizon for a relatively short time and sets shortly after the sunset. In different seasons, the Moon in this phase follows its daily path differently. It reaches its greatest height above the horizon in the summer. In other seasons, the young Moon rises relatively low above the horizon, making its observation conditions unfavorable. Approximately a week after the new moon, the Moon's disc appears halfway illuminated. This phase is called the first quarter. A characteristic feature of the first quarter phase is the alignment of the terminator with the horn line. The difference in longitude between the Moon and the Sun is exactly 90°. During this phase, the Moon is observable for a longer time over the horizon in the first half of the night. The most favorable season for observations falls in the spring.
Between 8 to 13 days old, the lunar disc is in the waxing crescent stage. The illuminated portion of the disc increases, and by the end of the second week after the new moon, the Moon can be seen fully illuminated. This phase is called the full moon. The Moon shines brightest, visible for almost the entire night except for the early morning hours. The most favorable observation season falls at the end of winter and the beginning of spring.
During the full moon, the Moon is almost directly opposite the Sun, so it rises at sunset and sets at sunrise.
In the first week after the full moon, the lunar disc is in the waning gibbous phase. The illuminated portion of the disc gradually decreases. During this period, against the backdrop of stars, the Moon once again starts moving closer to the Sun, approaching it from the opposite side. Its visibility extends for most of the night, except for the evening hours, with the most favorable observation time being the end of autumn and the beginning of winter.
At the end of the week after the full moon, the lunar disc remains only halfway lit, ushering in the last quarter phase. During the last quarter, the Moon is visible in the early hours of the night. In this phase, the Moon reaches its greatest height above the horizon in autumn.
Continuing to track the dynamic change of the Moon's phases, we will see the illuminated half-disk transform into a gradually narrowing crescent, marking the waning crescent phase. The observation time shifts to the predawn hours, with the most favorable season for observations being the late summer and early autumn. During the waning crescent phase, the Moon's rising time gradually approaches sunrise, and eventually, the lunar disc becomes invisible. The cycle of phase change is complete. In two to three days during the evening hours following the sunset, a narrow crescent of the new moon appears in the sky, and the entire cycle repeats anew.
I would like to add: In folklore, there are expressions related to the visual perception of Moon Phases such as "The Full Moon will last 3-4 days, the Full Moon will last for 4 days, the New Moon will be 3-4 nights, etc." These expressions are fundamentally incorrect. The true Full Moon or New Moon lasts only 1 minute. For example, when the lunar disc is already fully visible but has not yet reached its maximum phase, it is still considered Waxing. Or when the lunar disc has disappeared from view and is not visible, but has not yet reached the maximum Waning phase, it is still considered Waning Moon, not the New Moon. Once the Moon's disc reaches its maximum Waxing or Waning phase, it is considered either Waxing or Waning just one minute after that astronomical moment. One minute after the maximum phase, and that's it, the phase immediately shifts to the next one.
The Moon in the zodiacal constellation
Approximately, this can be done from direct observations, taking the data about the Moon phase from a regular wall calendar (keep in mind that during a new moon, the Moon is "ahead" of the Sun, in the first quarter - 90 degrees to the east of the Sun, at full moon - 180 degrees, and finally, in the last quarter - 90 degrees to the west of the Sun).
One can use a movable star map to approximate the positions of the Moon.
However, the most reliable and accurate way to determine the Moon's position in the celestial sphere is by using astronomical software-planetariums on a personal computer. With such programs, one can determine the position not only of the Moon and the Sun but also of planets, comets, asteroids, and even artificial satellites of the Earth.
To understand how the Moon moves across the celestial sphere, let's trace its path from new moon to the next new moon.
The observed speed of the Moon's movement among the stars is higher than the speed of a similar movement of the Sun. In a day, the Moon covers an angular distance equal to 13.2 degrees, i.e., it shifts by the magnitude of its own angular diameter (30 arc minutes) every hour. The Sun moves among the stars much slower - only 1 degree per day.
The duration of the cycle of changing phases is 29.5 days - synodic month.
During each month, the Moon, moving among the stars in the same direction as the Sun, catches up to our luminary and overtakes it. The moment when the astronomical longitudes of the Moon and the Sun are equal corresponds to the new moon phase, taken as the arbitrary beginning of the Moon's phase cycle. Formally, the period of visibility of the new moon phase falls within daylight hours. It is also evident that this phase is practically unobservable.
After the Moon reaches the position of its closest approach to the Sun, the narrow bright crescent starts to grow.
In the phase of the thin crescent, the Moon appears shortly after sunset and sets near the point of sunset. The convex side of the crescent Moon, facing the Sun, is called the illuminated limb of the visible disc of the Moon. The concave side of the crescent represents the boundary of the shadow on the lunar surface and is called the terminator. The Moon in the phases immediately following the new moon is called the young or waxing crescent.
The ends of the crescent at the intersection of the terminator with the limb are called horns, and the diameter of the visible disc that passes through these points is the horn line.
In astronomical literature, one often encounters the phrase "Moon age," which signifies the period of time elapsed since the last new moon.
A young or waxing Moon remains above the horizon for a relatively short time and sets shortly after the sunset. In different seasons, the Moon in this phase follows its daily path differently. It reaches its greatest height above the horizon in the summer. In other seasons, the young Moon rises relatively low above the horizon, making its observation conditions unfavorable. Approximately a week after the new moon, the Moon's disc appears halfway illuminated. This phase is called the first quarter. A characteristic feature of the first quarter phase is the alignment of the terminator with the horn line. The difference in longitude between the Moon and the Sun is exactly 90°. During this phase, the Moon is observable for a longer time over the horizon in the first half of the night. The most favorable season for observations falls in the spring.
Between 8 to 13 days old, the lunar disc is in the waxing crescent stage. The illuminated portion of the disc increases, and by the end of the second week after the new moon, the Moon can be seen fully illuminated. This phase is called the full moon. The Moon shines brightest, visible for almost the entire night except for the early morning hours. The most favorable observation season falls at the end of winter and the beginning of spring.
During the full moon, the Moon is almost directly opposite the Sun, so it rises at sunset and sets at sunrise.
In the first week after the full moon, the lunar disc is in the waning gibbous phase. The illuminated portion of the disc gradually decreases. During this period, against the backdrop of stars, the Moon once again starts moving closer to the Sun, approaching it from the opposite side. Its visibility extends for most of the night, except for the evening hours, with the most favorable observation time being the end of autumn and the beginning of winter.
At the end of the week after the full moon, the lunar disc remains only halfway lit, ushering in the last quarter phase. During the last quarter, the Moon is visible in the early hours of the night. In this phase, the Moon reaches its greatest height above the horizon in autumn.
Continuing to track the dynamic change of the Moon's phases, we will see the illuminated half-disk transform into a gradually narrowing crescent, marking the waning crescent phase. The observation time shifts to the predawn hours, with the most favorable season for observations being the late summer and early autumn. During the waning crescent phase, the Moon's rising time gradually approaches sunrise, and eventually, the lunar disc becomes invisible. The cycle of phase change is complete. In two to three days during the evening hours following the sunset, a narrow crescent of the new moon appears in the sky, and the entire cycle repeats anew.
I would like to add: In folklore, there are expressions related to the visual perception of Moon Phases such as "The Full Moon will last 3-4 days, the Full Moon will last for 4 days, the New Moon will be 3-4 nights, etc." These expressions are fundamentally incorrect. The true Full Moon or New Moon lasts only 1 minute. For example, when the lunar disc is already fully visible but has not yet reached its maximum phase, it is still considered Waxing. Or when the lunar disc has disappeared from view and is not visible, but has not yet reached the maximum Waning phase, it is still considered Waning Moon, not the New Moon. Once the Moon's disc reaches its maximum Waxing or Waning phase, it is considered either Waxing or Waning just one minute after that astronomical moment. One minute after the maximum phase, and that's it, the phase immediately shifts to the next one.
