When asked the time of sunrise and sunset on September 23, asked by the author Spikelets the best answer is Observing the diurnal movement of the Sun throughout the year, one can easily notice in its movement a number of features that differ from the diurnal movement of stars. The most typical of them are as follows.
1. The place of sunrise and sunset, and hence its azimuth, change from day to day. Starting from March 21 (when the Sun rises at the point in the east and sets at the point in the west) to September 23, the sunrise is observed in the northeastern quarter, and set - in the northeastern quarter. At the beginning of this time, the points of sunrise and sunset move to the north, and then in the opposite direction. On September 23, just like on March 21, the Sun rises at the point of the east and sets at the point of the west. Starting from September 23 to March 21, a similar phenomenon will be repeated in the south-skeleton and south-west quarters. The movement of the points of sunrise and sunset has a one-year period.
Stars always rise and set at the same points on the horizon.
2. The meridional height of the Sun changes every day. For example, in Odessa (cf = 46 °, 5 N) on June 22, it will be the largest and equal to 67 °, then it will begin to decrease and on December 22, it will reach the lowest value of 20 °. After December 22, the meridional height of the Sun will begin to increase. This phenomenon is also a one-year period. The meridional heights of stars are always constant. 3. The length of time between the culminations of a star and the Sun is constantly changing, while the length of time between two culminations of the same stars remains constant. So, at midnight we see the culminating constellations that are currently on the opposite side of the sphere from the Sun. Then some constellations give way to others, and during the year at midnight all the constellations are consecutively culminated.
4. The length of the day (or night) is variable throughout the year. This is especially noticeable if we compare the duration of summer and winter days at high latitudes, for example, in Leningrad. This happens because the time the Sun spends over the horizon during the year is different. The stars above the horizon are always the same amount of time.
Thus, the Sun, in addition to the daily movement performed together with the stars, also has a visible movement along the sphere with an annual period. This movement is called the apparent annual movement of the Sun in the celestial sphere.
We will get the most vivid idea of this movement of the Sun if we determine its equatorial coordinates every day - right ascension a and declination b Then, using the found coordinates, we will plot points on the auxiliary celestial sphere and connect them with a smooth curve. As a result, we get a large circle on the sphere, which will indicate the path of the apparent annual motion of the Sun. The circle on the celestial sphere, along which the Sun moves, is called the ecliptic. The plane of the ecliptic is inclined to the plane of the equator at a constant angle g = 23 ° 27 ", which is called the angle of inclination of the ecliptic to the equator.

Perhaps on this day you will have to choose between "black" and "white", without any half-tones. If you hesitate and cannot make an important step in any way, then either postpone the decision for a while, or consult with those you trust.

Things on the love front can go uphill. Very soon you yourself will notice the changes that will begin to occur in your soul and consciousness. Although this does not mean that you will meet a new partner if your heart is already taken. You can reconsider your relationship with a person whom you know, as you think, quite well.

If now you are destined to meet a pleasant person of the opposite sex, then do not rush to be frank and invite him to visit. Soon you will realize that this is not your soul mate. But for negotiations, signing of business papers and important meetings, this day is quite successful.

Although this day will be filled with vanity, it cannot be said that it will be empty. Along the way, you will have time to solve important issues with minor problems. You should not negotiate with your superiors. It's best if your paths don't cross.

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The day can be successful, provided that you do not start arguments and quarrels with loved ones. Do social or pleasure activities. Much can be done, and you will feel a sense of pride in yourself. Remember: now almost everything depends on you.

It is likely that you are in for a change for the better in your professional field. Promotion is possible. Start preparing for a pleasant change and gathering the information you need. In love affairs at this stage, you may have a second wind. And some will be able to find their love.

You will have a huge supply of strength and energy, so do not waste precious time, but deal with issues that seemed difficult before. You should be fine now. Indulge in shopping. Allow yourself to acquire the things you have dreamed of for a long time.

The day is going to be huge, both physically and emotionally. Treat everything that happens like a life exam to pass. Try to do pleasant things in your free moments that will allow you to relax and get away from worries. By the way: you are on the verge of very pleasant events.

You can outline the most serious cases that you have not wanted to take on for a long time. Now a lot will be on the shoulder - there would be a desire. If someone asks you for advice or help (not financial), do not deny the person a service, if, of course, it will be within your power and competence. Be careful with money - keep your wallet with you.

In the professional field, now everything will happen according to the planned schedule. Try to pay more attention to your health, be outdoors more often, especially in the company of people you like. In love, only pleasant emotions await you. However, do not forget that you are not the crown of creation, you should not test the patience of your half.

Now on the path of life you may face a test that will have to pass. And a lot will depend on how you cope with this task. Don't ask people you don't trust for help. They are the ones who are currently able to mix your cards.

The day is auspicious in many ways, so make plans, implement bold ideas and do not doubt your success. Try to maintain a comfortable rhythm in your work, do not let your colleagues rush or delay you. A change of scenery will be beneficial. Pleasant meetings, wonderful rest in good company await you.

The data of the lunar calendar, sunrise, sunset and moonset for September 23, 2017 are given for Moscow and the Moscow region.

§ 52. Apparent annual motion of the Sun and its explanation

Observing the diurnal movement of the Sun throughout the year, one can easily notice in its movement a number of features that differ from the diurnal movement of stars. The most typical of them are as follows.

1. The place of sunrise and sunset, and hence its azimuth, change from day to day. Starting from March 21 (when the Sun rises at the point in the east and sets at the point in the west) to September 23, the sunrise is observed in the northeastern quarter, and set - in the northeastern quarter. At the beginning of this time, the points of sunrise and sunset move to the north, and then in the opposite direction. On September 23, just like on March 21, the Sun rises at the point of the east and sets at the point of the west. Starting from September 23 to March 21, a similar phenomenon will be repeated in the south-skeleton and south-west quarters. The movement of the points of sunrise and sunset has a one-year period.

Stars always rise and set at the same points on the horizon.

2. The meridional height of the Sun changes every day. For example, in Odessa (cf = 46 °, 5 N) on June 22, it will be the largest and equal to 67 °, then it will begin to decrease and on December 22, it will reach the lowest value of 20 °. After December 22, the meridional height of the Sun will begin to increase. This phenomenon is also a one-year period. The meridional heights of stars are always constant. 3. The length of time between the culminations of a star and the Sun is constantly changing, while the length of time between two culminations of the same stars remains constant. So, at midnight we see the culminating constellations that are currently on the opposite side of the sphere from the Sun. Then some constellations give way to others, and during the year at midnight all the constellations are consecutively culminated.

4. The length of the day (or night) is variable throughout the year. This is especially noticeable if we compare the duration of summer and winter days at high latitudes, for example, in Leningrad. This happens because the time the Sun spends over the horizon during the year is different. The stars above the horizon are always the same amount of time.

Thus, the Sun, in addition to the daily movement performed together with the stars, also has a visible movement along the sphere with an annual period. This movement is called visible. the annual motion of the Sun across the celestial sphere.

We will get the most vivid idea of this movement of the Sun if we determine its equatorial coordinates every day - right ascension a and declination b Then, using the found coordinates, we will plot points on the auxiliary celestial sphere and connect them with a smooth curve. As a result, we get a large circle on the sphere, which will indicate the path of the apparent annual motion of the Sun. The circle on the celestial sphere, along which the Sun moves, is called the ecliptic. The plane of the ecliptic is inclined to the plane of the equator at a constant angle g = 23 ° 27 ", which is called the angle of inclination ecliptic to the equator(fig. 82).

Rice. 82.

The apparent annual movement of the Sun along the ecliptic occurs in the direction opposite to the rotation of the celestial sphere, that is, from west to east. The ecliptic intersects the celestial equator at two points, which are called the equinox points. The point at which the Sun moves from the southern hemisphere to the northern, and therefore changes the name of the declination from south to north (i.e., from bS to bN), is called a point vernal equinox and is denoted by the Y icon. This sign denotes the constellation Aries, in which this point was once located. Therefore, it is sometimes called the point of Aries. Point T is currently in the constellation Pisces.

The opposite point, at which the Sun moves from the northern hemisphere to the southern and changes the name of its declination from b N to b S, is called the point of the autumnal equinox. It is designated by the sign of the Libra constellation O, in which it was once located. Currently, the point of the autumnal equinox is in the constellation Virgo.

Point L is called summer point, and point L "- point winter solstices.

Let's trace the apparent movement of the Sun along the ecliptic throughout the year.

The Sun comes to the vernal equinox on March 21st. Right ascension a and declination of the Sun b are equal to zero. Throughout the globe, the Sun rises at point O st and sets at point W, and day is equal to night. Since March 21, the Sun has been moving along the ecliptic towards the point of the summer solstice. Right ascension and declination of the Sun are continuously increasing. Astronomical spring is coming in the northern hemisphere, and autumn in the southern hemisphere.

On June 22, about 3 months later, the Sun comes to the point of the summer solstice L. Right ascension of the Sun a = 90 °, and declination b = 23 ° 27 "N. Astronomical summer begins in the northern hemisphere (the longest days and shortest nights), and in the south it is winter (the longest nights and the shortest days). As the Sun continues to move, its north declination begins to decrease, while right ascension continues to increase.

Approximately three months later, on September 23, the Sun comes to the point of the autumnal equinox Q. Right ascension of the Sun a = 180 °, declination b = 0 °. Since b = 0 ° (like March 21), then for all points on the earth's surface the Sun rises at point O st and sets at point W. Day will be equal to night. The name of the declination of the Sun changes from north 8n to south - bS. Astronomical autumn is coming in the northern hemisphere, and spring in the southern hemisphere. With further movement of the Sun along the ecliptic to the winter solstice point U, declination 6 and right ascension aO increase.

On December 22, the Sun comes to the point of the winter solstice L ". Right ascension a = 270 ° and declination b = 23 ° 27" S. Astronomical winter sets in in the northern hemisphere, and summer in the southern.

After December 22, the Sun moves to point T. The name of its declination remains south, but decreases, and right ascension increases. Approximately 3 months later, on March 21, the Sun, having completed a full revolution along the ecliptic, returns to the point of Aries.

Changes in right ascension and declination of the Sun do not remain constant throughout the year. For approximate calculations, the daily change in the right ascension of the Sun is taken equal to 1 °. The change in declination per day is taken equal to 0 °, 4 within one month before the equinox and one month after, and the change to 0 °, 1 within one month before the solstices and one month after the solstices; the rest of the time, the change in the declination of the Sun is taken equal to 0 °, 3.

The peculiarity of the change in the right ascension of the Sun plays an important role in the choice of the basic units for measuring time.

The vernal equinox moves along the ecliptic towards the annual motion of the Sun. Its annual displacement is 50 ", 27 or 50", 3 (for 1950). Consequently, the Sun does not reach the original location relative to the fixed stars by a magnitude of 50 ", 3. For the Sun to travel the specified path, it will take 20 m m 24 s. For this reason, the spring

It comes before the Sun ends and its apparent annual motion is a full circle of 360 ° relative to fixed stars. The shift in the moment of the onset of spring was discovered by Hipparchus in the II century. BC NS. from the observations of the stars that he made on the island of Rhodes. He called this phenomenon the anticipation of the equinoxes, or precession.

The phenomenon of displacement of the vernal equinox point made it necessary to introduce the concepts of tropical and stellar years. The tropical year is called the period of time during which the Sun makes a full revolution in the celestial sphere relative to the vernal equinox T. "The duration of the tropical year is 365.2422 days. The tropical year is consistent with natural phenomena and precisely contains the full cycle of the seasons of the year: spring, summer, autumn and winter.

A sidereal year is called the period of time during which the Sun makes a complete revolution in the celestial sphere relative to the stars. The duration of a sidereal year is 365.2561 days. A sidereal year is longer than a tropical one.

In its apparent annual motion across the celestial sphere, the Sun passes among various stars located along the ecliptic. Even in ancient times, these stars were divided into 12 constellations, most of which were given the names of animals. The strip of sky along the ecliptic, formed by these constellations, was called the Zodiac (circle of animals), and the constellations - zodiacal.

According to the seasons of the year, the Sun passes the following constellations:

From the joint motion of the Sun-annual along the ecliptic and diurnal due to the rotation of the celestial sphere, a general motion of the Sun along a spiral line is created. The extreme parallels of this line are removed on both sides of the equator at distances of в = 23 °, 5.

On June 22, when the Sun describes the extreme diurnal parallel in the northern celestial hemisphere, it is in the constellation Gemini. In the distant past, the Sun was in the constellation Cancer. On December 22, the Sun is in the constellation Sagittarius, and in the past it was in the constellation Capricorn. Therefore, the northernmost celestial parallel was called the Tropic of Cancer, and the southern - the Tropic of Capricorn. The corresponding earthly parallels with latitudes cp = betax = 23 ° 27 "in the northern hemisphere were called the Tropic of Cancer, or the northern tropic, and in the southern, the tropic of Capricorn, or the southern tropic.

In the joint motion of the Sun, which occurs along the ecliptic with the simultaneous rotation of the celestial sphere, there are a number of features: the length of the diurnal parallel above the horizon and below the horizon (and, consequently, the length of the day and night) changes, the meridional heights of the Sun, the points of sunrise and sunset, etc. All these phenomena depend on the relationship between the geographical latitude of a place and the declination of the Sun. Therefore, for an observer at different latitudes, they will be different.

Consider these phenomena in some latitudes:

1. The observer is at the equator, cp = 0 °. The axis of the world lies in the plane of the true horizon. The celestial equator coincides with the first vertical. Diurnal parallels of the Sun are parallel to the first vertical, therefore the Sun in its diurnal movement never crosses the first vertical. The sun rises and sets daily. Day is always equal to night. The Sun is at its zenith twice a year - on March 21 and September 23.

Rice. 83.

2. The observer is at latitude φ
3. The observer is at latitude 23 ° 27 "
4. The observer is at latitude φ> 66 ° 33 "N or S (Fig. 83). The belt is polar. The parallels φ = 66 ° 33" N or S are called polar circles. In the polar belt, polar days and nights can be observed, that is, when the Sun is above the horizon for more than a day or more than a day below the horizon. The longer the latitude, the longer the polar days and nights. The sun rises and sets only on days when its declination is less than 90 ° -φ.

5. The observer is at the pole φ = 90 ° N or S. The axis of the world coincides with the plumb line and, therefore, the equator is with the plane of the true horizon. The position of the observer's meridian will be uncertain, so parts of the world are missing. During the day, the sun moves parallel to the horizon.

On the days of the equinox, there are polar sunrises or sunsets. On the days of the solstices, the height of the Sun reaches its highest values. The height of the Sun is always equal to its declination. The polar day and the polar night last for 6 months.

Thus, due to various astronomical phenomena caused by the joint daily and annual movement of the Sun at different latitudes (passage through the zenith, the phenomena of the polar day and night) and the climatic features caused by these phenomena, the earth's surface is divided into tropical, temperate and polar belts.

Tropical belt is called the part of the earth's surface (between latitudes φ = 23 ° 27 "N and 23 ° 27" S), in which the Sun rises and sets every day, and twice a year is at its zenith. The tropical belt occupies 40% of the entire earth's surface.

Moderate belt is called the part of the earth's surface in which the sun rises and sets daily, but is never at its zenith. There are two temperate zones. In the northern hemisphere, between latitudes φ = 23 ° 27 "N and φ = 66 ° 33" N, and in the southern hemisphere between latitudes φ = 23 ° 27 "S and φ = 66 ° 33" S. Temperate belts occupy 50% of the earth's surface.

Polar belt is called the part of the earth's surface in which polar days and nights are observed. There are two polar belts. The North Polar Belt extends from latitude φ = 66 ° 33 "N to the North Pole, and the southern one extends from φ = 66 ° 33" S to the South Pole. They occupy 10% of the earth's surface.

For the first time, Nicolaus Copernicus (1473-1543) gave a correct explanation of the apparent annual motion of the Sun in the celestial sphere. He showed that the annual movement of the Sun along the celestial sphere is not its actual movement, but only the visible, reflecting the annual movement of the Earth around the Sun. Copernicus' system of the world has been called heliocentric. According to this system, in the center of the solar system is the Sun, around which the planets move, including our Earth.

The Earth simultaneously participates in two movements: it rotates around its axis and moves in an ellipse around the Sun. The rotation of the Earth around its axis causes the change of day and night. Its movement around the Sun causes the change of seasons. From the joint rotation of the Earth around its axis and movement around the Sun, there is a visible movement of the Sun along the celestial sphere.

To explain the apparent annual motion of the Sun in the celestial sphere, let us use Fig. 84. In the center is the Sun S, around which the Earth moves counterclockwise. The earth's axis remains unchanged in space and makes an angle with the ecliptic plane equal to 66 ° 33 ". Therefore, the equatorial plane is inclined to the ecliptic plane at an angle e = 23 ° 27". Next comes the celestial sphere with the ecliptic and the signs of the constellations of the Zodiac in their modern arrangement applied on it.

The Earth comes to position I on March 21st. When viewed from Earth, the Sun is projected onto the celestial sphere at point T, which is currently in the constellation Pisces. The declination of the Sun is e = 0 °. An observer at the Earth's equator sees the Sun at noon at its zenith. All earthly parallels are half illuminated, therefore, at all points of the earth's surface, day is equal to night. Astronomical spring begins in the northern hemisphere, and autumn begins in the southern hemisphere.

Rice. 84.

The Earth comes to position II on June 22. Declination of the Sun b = 23 °, 5N. Seen from Earth, the Sun is projected into the constellation Gemini. For an observer at latitude φ = 23 °, 5N, (The sun passes through the zenith at noon. Most of the diurnal parallels are illuminated in the northern hemisphere and less in the southern. The northern polar belt is illuminated and the southern one is not illuminated. The polar day lasts on the northern one, and on the south - polar night.In the northern hemisphere of the Earth, the sun's rays fall almost vertically, and in the southern - at an angle, so in the northern hemisphere there is an astronomical summer, and in the southern - winter.

The Earth comes to position III on September 23rd. The declination of the Sun is bo = 0 ° and it is projected to the point of Libra, which is now in the constellation Virgo. An observer at the equator sees the Sun at noon at its zenith. All terrestrial parallels are half illuminated by the Sun, therefore, at all points on the Earth, day is equal to night. Astronomical autumn begins in the northern hemisphere, and spring begins in the southern.

On December 22nd, the Earth comes to position IV. The sun is projected into the constellation of Sagittarius. Declination of the Sun 6 = 23 °, 5S. In the southern hemisphere, most of the diurnal parallels are illuminated than in the northern, therefore, in the southern hemisphere, the day is longer than night, and in the northern - vice versa. The sun's rays fall almost vertically in the southern hemisphere, and at an angle to the northern. Therefore, astronomical summer begins in the southern hemisphere, and winter in the northern one. The sun illuminates the southern polar belt and does not illuminate the northern one. A polar day is observed in the southern polar belt, and night is observed in the northern one.

Corresponding explanations can be given for the rest of the intermediate positions of the Earth.

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