When is the equinox in spring? Spring and autumn equinox

Equinoxes imply at least basic knowledge of astronomical terms, because the equinox itself is a phenomenon studied by this particular science.

Required knowledge of astronomical terms

Our star moves along the ecliptic, which is, in non-scientific language, the plane of the earth's orbit. And the moment when the sun, making its way along the ecliptic, crosses the celestial equator, which is a large circle of air and parallel to the earth’s equator (their planes coincide, and both of them are perpendicular to the axis of the world), is called the equinox. also an astronomical concept that has nothing to do with Schwarzenegger) is a line that divides any celestial body into the sunlit part and the “night part”. So, on the day of the equinox, it is this terminator that passes through the geographic poles of the Earth and divides it into two equal half-ellipses.

Characteristic feature contained in the name

The name itself contains the concept that on the day of the equinox, night and day are equal. From a scientific point of view, the night is always a little shorter, and the sun rises and sets not exactly in the east and west, but slightly to the north. But still, from childhood, we know that June 22 is not only the day the war began and school proms (this was the case in Soviet time), but also the day of the summer equinox. However, December 22 is also called the summer and winter solstice. This happens because the sun during these periods of time is either at its high point above the horizon, or lowest and furthest from the celestial equator. That is, on the day of the equinox, the light and dark parts of the day are almost equal to each other.

The number characteristic of the equinox and solstice

On the days of the solstices, one of them - either day or night - maximally exceeds the other. The equinoxes and solstices are also notable for the fact that they mark the beginning of the changing seasons. These dates are very remarkable, and one of the family members always says that today is the longest or shortest day, or that today is equal to night. And this sets him apart from the series of consecutive days. Almost always the date of these moments is the 22nd, but there are also leap years, and other moments and phenomena of astronomy that influence the date shift to the 21st or 23rd. The months of March, June, September and December are those in which the equinoxes and solstices fall.

Holidays that come from ancient times

Of course, they have been known since ancient times. Our ancestors observed them and connected their lives with these dates; dozens of signs bear witness to this. The ancient Slavs have a specific holiday associated with each of these days, and it usually lasts a week (Carols, Rusalia, Maslenitsa Week). So, on the winter solstice there is Kolyada, a holiday later dedicated to Christmas. Great Day, or Komoeditsa, also known as Maslenitsa - these names mark the spring equinox, the birth of the young sun. From this day begins the astrological solar year, and our luminary moves to from the South. Maybe that’s why March 20 is an astrological holiday. Kupala (other names Midsummer Day, Solstice), or summer confrontation, is a great summer holiday of the ancient Slavs, covered in legends that glorified brave people who went out that night to look for a fern flower. Ovsen-Tausen, the day of the autumn equinox, after which winter slowly begins to take over, and the nights become longer. Therefore, our ancestors lit candles in Svyatovit (another name) - the most beautiful one was placed in a place of honor.

Special climate zone of the Earth

All these dates served as starting points for the beginning of certain activities necessary for life - seasonal types of agriculture, construction or winter supplies. The days of the spring and autumn equinox are also characterized by the fact that the sun gives off its light and heat equally to both the Northern and Southern Hemispheres, and its rays reach both poles. These days it is located over the territory of such climatic zone Earths like the tropics (translated from Greek language means turning circle). In different directions from the equator to a little over 23 degrees, parallel to it are the northern and southern tropics. Characteristic feature The area enclosed between them is that above them twice a year the Sun reaches its zenith - once on June 22 over the northern tropic, or Tropic of Cancer, the second time - over the southern, or Tropic of Capricorn. This happens on December 22. This is typical for all latitudes. The Sun is never at its zenith north or south of the tropics.

One of the consequences of a shift in the direction of the earth's axis

On the days of the equinox and solstices, it intersects with the celestial equator at points located in (spring) and Virgo (autumn), and on the days of greatest and least distance from the equator, that is, on the days of the summer and winter solstices, in the constellations Taurus and Sagittarius, respectively . The summer solstice point moved from the zodiac constellation Gemini to Taurus in 1988. Under the influence of the attraction of the Sun and Moon, the earth's axis slowly shifts its direction (precession is another astronomical term), as a result of which the points of intersection of the luminary with the celestial equator also shift. Spring dates differ from autumn dates, and if September falls on the 22nd-23rd, then the question “When is the day spring equinox? the answer will be March 20th. It should be noted that for the Southern Hemisphere the dates will be reversed - autumn dates will become spring dates, because there everything is the other way around.

The role of the zodiac constellations

As noted above, the equinox points are the intersection points of the celestial equator with the ecliptic, and they have their own zodiac symbols corresponding to the constellations in which they are located: spring - Aries, summer - Cancer, autumn - Libra, winter - Capricorn. It should be noted that the period of time between two equinoxes of the same name is called a tropical year, the number sunny days in which differs from approximately 6 hours. And only thanks to the leap year, which repeats itself once every 4 years, does the date of the next equinox, which is running ahead, return to its previous date. The difference with the Gregorian year is negligible (tropical - 365.2422 days, Gregorian - 365.2425), because this modern calendar is designed in such a way that even in the long term the dates of the solstices and equinoxes fall on the same dates. This happens because it provides for a 3-day pass once every 400 years.

One of the most important practical tasks of astronomy is establishing the date of the equinox.

Dates range from 1 to 2, no more, days. So how can we determine in the coming years when the equinox is? It is noticed that as a result of the presence of slight fluctuations, the earliest dates, that is, the 19th, fall on leap years. Naturally, the latest ones (22) fall directly on the preceding leap days. Very rarely are there earlier and later dates, the memory of them is preserved for centuries. So, back in 1696, the spring equinox fell on March 19, and in 1903, the autumn equinox fell on September 24. Contemporaries will not see such deviations, because the repetition of the 1696 record will occur in 2096, and the latest equinox (September 23) will occur no earlier than 2103. There are nuances associated with local time - a deviation in the number from the world time occurs only when the exact date falls on 24:00. After all, to the west of the reference point - the prime meridian - a new day has not yet arrived.

Solstice(also solstice) - an astronomical event, the moment of passage of the center of the Sun through the points of the ecliptic, most distant from the equator of the celestial sphere and called solstice points.

Equinox- an astronomical phenomenon when the center of the Sun, in its apparent movement along the ecliptic, crosses the celestial equator. When observing the Earth from space at the equinox, the terminator passes along geographic poles Earth and perpendicular to the Earth's equator.

These dates were among the most revered in the pre-Christian period. Solstice, rotation, equinox, solstice are the names of solar holidays, which are also called the four hypostases of the Slavic Dazhdbog, which is the Sun itself - the son of Svarog.

• Kolyada– winter solstice (December 21-22)
• Maslenitsa or Komoeditsy– vernal equinox (March 21-22)
• Kupailo (Kupala)– summer solstice (June 21-22)
• Radogoshch (Svetovit, Veresen, Tausen)– autumnal equinox (September 22-23)

Kolyada– winter solstice or the longest night of the year. During this period, the young sun Kolyada replaces the old sun Svetovit in his post. That is why the daylight hours begin to increase from this day on. Replaced by the church on Christmas Day.

Maslenitsa or Komoeditsy– the day of the vernal equinox (day and night are equal in time), farewell to winter, burning of the effigy of Madder, welcoming spring and the Slavic New Year. The date March 21-22 is also the beginning of astronomical spring. From this day on, the day becomes longer than the night. Yarilo-Sun replaces Kolyada and drives away Winter-Madder. Traditionally, this bracelet was celebrated for two whole weeks.

Kupaylo- day of the summer solstice. The longest day and shortest night of the year. The last day of Rusal Week or Rusalia. Kupala is one of the oldest holidays, which has kept many traditions and customs unchanged to this day, for example: the funeral of Yarila, who is replaced by the God of the summer sun Kupala, the gathering medicinal herbs, searching for a fern flower, etc. Kupailo is also a great holiday, which is now replaced by the church on the birthday of John the Baptist.

Radogoshch(Svetovit, Veresen, Tausen) - the day of the autumnal equinox (day and night are equal in time). On this day, the Sun-Old Man Svetovit comes into his own. The night becomes longer than the day. It is both a solar holiday and a celebration of the end of the harvest. Replaced by the church for the Nativity of the Blessed Virgin Mary.

Position of the sun on solstice days

The periods between solstices are the times when the sun moves either higher above the horizon or lower.

Astronomers note that the movement of the hot star is similar to a sine wave:

• after the winter solstice it rises higher every day
• after the summer - on the contrary, it drops lower

The angle created by the sun and the earth's horizon, in other words, the astronomical longitude of the hot star, is:

• 90° in June
• 270° in December

In astronomy, from the moment the Sun enters the zodiac sign of Taurus in June, summer begins, and winter begins in the sign of Sagittarius in December. A few days before and after the solstice, the hot celestial body “freezes” at one point at noon.

However, you won't see the sun directly overhead on the solstices.

If you are a resident of the northern hemisphere of the Earth, then:

• go 23.5° above the equator before the summer solstice to see the hot planet vertically above you,
• visit 23.5°S to see a similar phenomenon during the winter solstice.

Position of the sun at the equinoxes

The equinoxes represent a certain milestone when the sun moves from the northern to the southern hemisphere in the fall and vice versa in the spring. This is for the part of our planet that is located above the equator. These days the sun directs its rays in such a way that they evenly warm up the entire part of the Earth facing it.

Another feature of these calendar dates is that the day before and after, as well as during the equinox, the sun rises clearly in the east and sets in the west. True, this phenomenon is typical only for 23.5° north or south latitude. In other areas there is a slight shift to the north or south.

Equinoxes and solstices: magic

These 4 days of the year have maximum energy not only because of the change of times. The Slavs knew this very well and harmoniously structured their lives in such a way as to streamline and develop their relationships with nature.

A common feature during the celebrations of all solstices and equinoxes among our ancestors were mass celebrations.

The whole village gathered together:

• Various games and fun were held
• there were round dances
• everyone ate
• praised the gods
• commemorated ancestors

Everything happened fun, easily and naturally.

• We still celebrate the summer solstice as Kupala. We are looking for the treasured fern flower in the hope of good luck and the fulfillment of our cherished dreams.
• On the autumn equinox, the ancestors held a harvest festival. Adults cleaned the house, yard, and fields. Children decorated their homes with bunches of rowan berries. It was believed that she would protect the house and its inhabitants from evil all year long.

The winter solstice, or the birth of Kolyada - the young sun, was celebrated on a special scale. There was a place here:

• fortune telling about the betrothed, marriage, weather for the next year, harvest
• caroling and dressing up as animals to scare away dark forces
• jumping over a fire to burn all resentment, envy and similar sins

Three days before and the same number after Kolyada had special power. Housewives put things in order in their heads and homes, and brought health and well-being into the life of the family. They watched the events of 12 days after Kolyada in order to understand what the coming year would bring for the family.

• The day of the spring equinox had special power. Nature was awakening from its winter sleep, a new year began for work on the land.
• At this time pancakes were being baked and it was Maslenitsa. But it lasted 2 weeks - one before, the second after the equinox.
• Housewives baked larks - small birds made from sweet dough.
• In the evening, everyone jumped over the fires to renew themselves for a new round of life. For example, if unmarried girl jumped, then she will definitely become the mother of a hero.

Every person after a long and cold winter dreams of the imminent arrival of the warm season. The vernal equinox 2018 will be the time when the Sun moves to the northern hemisphere and astronomical spring begins.

When does this day come?

The equinox occurs when the length of day and night becomes equal. This moment is observed when the Sun crosses the equator of the sky. The spring equinoxes are 365.24 solar days apart, so they occur at different time. Now astronomers have learned to accurately determine the day of the equinox several years in advance. For those who are interested in what date this event will occur in 2018, we can already answer with certainty. So, the sun's rays will hit the earth's equator vertically on 03/20/18.

A little history

In the history of mankind, four key dates can be noted, in accordance with which the life of ancient people was built. In 2018 they will look like this:

All these points are sacred. It is after these days that dramatic changes in nature occur. The most revered date among our ancestors was still the day of the vernal equinox. They were waiting for him with the greatest impatience. He personified the victory of light and gave hope for the future. It is not surprising that many peoples perceive this day as a real holiday. The darkness begins to recede and the days lengthen. In ancient times, the equinox was associated with the onset of spring. For some peoples, this day heralded the arrival of the New Year. After all, after it a new period began, when everything in nature and human life began to be renewed.

As for our people, in the Slavic world, Komoeditsa or Maslenitsa was celebrated on the equinox. On this day it was customary to say goodbye to winter.

How to celebrate

Transition to new life cycle was celebrated with great enthusiasm among all peoples. People tried to leave all the bad things in the past and hoped that the new period would bring them victories and good luck. This primarily concerned the future harvest. This day was revered by almost all peoples of our planet. Europeans held numerous festivals and masquerades during this period.

In pre-Christian Rus', when people worshiped pagan gods, the equinox was considered almost the most important day of the year. He was greeted with unprecedented joy and hope. The holidays lasted several days and were called Maslenitsa Week. Each day was designated for certain rituals:

• On Monday, housewives baked fragrant pancakes and larks, symbolizing the arrival of spring. The first pancake, according to custom, was intended for Who - the Bear God. It was believed that he protected men during hunting. On the same day, in Russian villages they built a stuffed animal from straw and old things, impaled it and carried it on a sleigh throughout the area.
• On Tuesday there was a viewing party. Early in the morning, the guys invited the girls to ride a sleigh, and in the evening the matchmakers went to the houses of the future brides to discuss the details upcoming wedding.
• On Wednesday, mothers-in-law invited their sons-in-law over for pancakes, showing them how much they respected them. On Thursday, folk festivities were held in all Russian villages with noisy, exciting games and fairs, where one could taste pancakes with different fillings and enjoy ancient drinks. Young people danced in circles and sang songs. The bravest ones took part in fist fights and jumped over the fire. The day ended with the capture of " snowy city" The purpose of all the events of this day was to throw out the negative energy that had accumulated over the winter.
• On other days, older people performed all sorts of rituals aimed at obtaining a rich harvest and strengthening family ties (mother-in-law parties, sister-in-law gatherings, etc.)
• On Sunday it was customary to ask each other for forgiveness. People also went to the bathhouse, trying to cleanse themselves of accumulated dirt, put on new and clean clothes and put an end to the past. Old and dilapidated things had to be burned these days. The main event of this holiday, of course, is the burning of a straw effigy - a symbol of winter. Previously, the ashes from the scarecrow were scattered across the fields in the hope of getting a good harvest.

Currently, many traditions associated with the equinox have been lost. However, some Russian cities still hold fairs where you can sample pies, pancakes and other baked goods. Performances by folk groups and master classes on various folk crafts are organized in the main squares. For this holiday, cafes and restaurants are adjusting their menus to include folk dishes.

Signs

In the old days, when making baked goods, housewives put various household items into the baked goods. So, if household members found in the lark, for example:

• a button, this meant a quick new thing;
• coin - wealth;
• flower - foreshadowed beauty for the owner;
• berry - was for health.

If a woman was pregnant, then during Maslenitsa one could easily find out the gender of the unborn baby. If a man took the first pancake, then an heir would be born, if a woman, then the future mistress.

According to Maslenitsa, the weather for the next forty days was easily predicted. If there was a holiday warm weather, then over the next month it was possible to forget about the frosts and prepare for work on the ground.

In ancient times, people were sure that on the equinox the heavens opened and their deepest desires were fulfilled. On this day it was customary to ask God for the most important things:

• about the future harvest;
• about the health and well-being of the whole family.

On this holiday it was forbidden to be sad. It was believed that on the day of the equinox everything can materialize, so cry and bad thoughts were banned. Joy and fun were a guarantee of a good mood on whole year.

This year March 20 is the vernal equinox. At 13:29 Moscow time, the Sun crosses the celestial equator in its apparent movement along the ecliptic. The length of day and night is the same throughout the Earth and is equal to 12 hours. The celestial equator is a projection earth's equator to the sphere of fixed stars, infinitely distant from us.

The sun does not move along the celestial equator, otherwise day would be equal to night every day, says leading researcher at the Institute of Astronomy of the Russian Academy of Sciences Alexander Bagrov. - No, the Sun moves along the ecliptic, slightly inclined. When the star rises above the ecliptic, we have a long day. When it goes lower, the nights are long. And only at the moment when the Sun passes through the celestial equator does day equal night. That's why the event is called the equinox, in contrast to the summer and winter solstices.

At two latest events, as the astronomer explains, the Sun is located as far as possible from the celestial equator. And then it turns out to be the longest day of the year - in the summer. Or the longest night is in winter.

Since ancient times, the spring equinox symbolizes the beginning of a new cycle in nature. And also - new beginnings in people's lives. From an astrological point of view, for example, the date of the vernal equinox is the day when the Sun enters 0 degrees Aries. This point is the beginning of the Zodiac. Once upon a time, the Sun actually rose against the background of the constellation Aries on the day of the spring equinox, but over time the equinox point has shifted, and now it is actually located in the constellation Pisces. Since the signs of the Zodiac are not associated with constellations, although they bear their names, the first sign of the Zodiac is still called Aries.

In the Northern Hemisphere, the vernal equinox marks the beginning of spring, and has long been celebrated as a time of rebirth, says Boris Manevich, candidate of historical sciences, teacher at Moscow State University. - This is a day of balance between day and night, light and darkness. In many cultures and religions, various holidays were dedicated to the spring equinox. On this day it was customary to perform all kinds of magical rituals. For example, after a number of preparations, plant seeds in a pot and make a wish. Then the seeds had to be cared for carefully and for a long time so that they would germinate and bear fruit. It was believed that with the appearance of fruits, wishes come true.

Magic is a creation of human consciousness. Simply put, it’s fiction,” astronomer Alexander Bagrov is skeptical. - We must understand that people have been engaged in agriculture or hunting since ancient times. Both were closely related to the seasons. Either the birds began migrating, then it was time to plow the land - in general, time had to be counted somehow. Observations helped in this count. For example, on March 20, day is equal to night. Yep, there is a starting point! From now on, the day will be longer than the night, you need to get the plow, and after plowing, sow.

As the scientist explained, science even now, unfortunately, does not know everything. And in ancient times she knew even less. Therefore, people made all kinds of guesses, supported them with rituals, which filled the void of scientific knowledge.

Easily explainable events now - for example, the same spring equinox - were given a certain magical meaning, people believed their own inventions, Bagrov explained. - But we cannot repeat their mistakes.

The equinox... happens twice a year, namely, when the equinox, equinox (equator) crosses the solar path: the spring equinox occurs on March 9; autumn - September 10. The equinoctial circle, the same, the equator.

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The vernal equinox for an earthly observer Sergey Ov"

Fig.1 The movement of the Sun on the Day of the Vernal Equinox in the area north of the Tropic of Cancer. Sunrise is near the east, sunset is near the west

Day of spring equinox- This the day when spring comes, believes the majority of the inhabitants of planet Earth.
Indeed, it is customary all over the world to read that on the day of the vernal equinox, astronomical spring begins in the Northern Hemisphere of the Earth, autumn in the Southern Hemisphere, well, but most of humanity still lives in the Northern Hemisphere...
That is why northerners look forward to the spring equinox, because with it spring comes and begins to get warmer!
A common misconception associated with the Equinox is that “on this day, the length of the day is equal to the length of the night.” In fact, in the northern hemisphere, the length of the day equalizes the length of the night a few days before the spring equinox. For example, at the latitude of Moscow, the length of the day usually begins to exceed the length of the night from March 18th.
This issue is discussed in detail in the article, which ultimately clearly shows that At the Equinox, the length of the day evens out to the greatest extent across the globe u.
It was this feature that was taken as fundamental for the name of the event: Equal day across the Earth = Equinox- this sounds unifying and in essence more true, in contrast to the twilight Western: "Equinox"(literally from Latin" equal to night" -This is where the roots of the universal centuries-old delusion are!).

How is the Day of the Spring Equinox “assigned” and what is the equinox?

Within the framework of modern astronomical science, the most obvious definition for an earthly observer has been adopted: The exact date of intersection of the center of the Sun with the celestial equator is called the moment of equinox. From the point of view of a space observer at the moment of the equinox, the tilt of the earth's axis coincides with the direction of its orbital motion(the plane of the earth's axis is perpendicular to the line connecting the centers of mass of the Earth and the Sun - Scheme 1).
Thus, the point of intersection of the celestial equator with the ecliptic through which the Sun passes moving from south to north is called vernal equinox point(ecliptic coordinates 0°, 0°; equatorial 00h00m00s, 0°; currently located in the constellation )

The point in the orbit at which the Earth is located at the moment of the vernal equinox is called orbital point of the vernal equinox .

The day of the Vernal Equinox is the day on which the moment of the vernal equinox falls.

In 2020, on the territory of Russia, the Vernal Equinox Day, the whole country celebrates the vernal equinox on March 20, since according to Moscow time the sun will pass the vernal equinox point on 03/20/2019 06:50 Moscow time.

Scheme 1. Planet Earth at the orbital point of the vernal equinox, the ecliptic plane and the tilt of the earth’s axis

Earth at the summer solstice and the tilt of the earth's axis
Earth at the vernal equinox, ecliptic and tilt of the earth's axis, mini

To enlarge the image and see explanations, click on it...

The main feature of the orbital point of the vernal equinox is that at this point the plane of the earth's axis perpendicular to the ecliptic also forms a right angle with the direction to the Sun and, therefore, the angle between the direction to the center of the Sun and the line of the earth's axis is exactly 90° (The Earth is rotated so that both poles are visible from the Sun).

Events associated with the spring equinox

According to the basics of celestial mechanics, as well as the Law of the Russian Federation “On the Calculation of Time,” the date of the vernal equinox in Central Russia in a leap year and the two following years is usually March 20, in the year preceding a leap year - March 21.

In 2020, the Earth will be at the vernal equinox March 20, 2020 06:50 MSK(03/20/2020 03:50 UTC - ).

The following events will occur:

1. It will come astronomical spring.
2. According to the zodiac position, the Sun will move into zodiac sign Aries.
3. Length of day all over the planet will be as equal as possible and will average 12 hours 8 minutes.
4. At the equator at noon The sun will be at its zenith.
5.The sun will rise almost exactly in the east, A will come in almost exactly on west (Fig.1).
6. By measuring the angle of maximum elevation of the Sun h sun(Fig.1), you can determine the latitude of the area φ = 90° -h sun, in Moscow, for example, φ = 90° - 34.460°=55.54°.
7. All over the Earth the day will be longer than the night.
8. In the Northern Hemisphere, a few days before the equinox, day will become equal to night ( in Germany, for example, such a day is specially marked as Equilux ), and a polar day will come beyond the Arctic Circle

On the morning of this day, at a clear dawn, a ray of sun will touch the stone marker of the vernal equinox at Stonehenge, just as in other ancient structures designed to provide calendar time.

Customs and traditions associated with the vernal equinox

IN pre-revolutionary Russia In the 18th and 19th centuries, the Vernal Equinox fell on March 9 (old style), on this day Soro Sorokov (Magpies) was celebrated, larks baked - this was the second meeting of spring, the first, as a rule, fell on Maslenitsa.
But in Japan, the Spring Equinox Day is a public holiday (Japanese: 春分の日 Shumbun no hi) and official holiday.
In Iran and India, countries where Zoroastrianism received official status, they celebrate the vernal equinox New Year. And in those territories where the descendants of the peoples who inhabited settled ancient Persia They celebrate “Novruz” - a holiday carefully preserved by the people for more than one millennium.
In Europe, all kinds of spring fairs and festivals are celebrated on this day, but stable traditions have not yet developed.

Unfortunately, nothing can be said reliably about the ancient Slavic celebrations on the eve of the spring equinox - practically nothing from the pagan mythology of Rus' has survived to this day.
True, you don’t need to have 100 spans in your forehead to guess that the “Feast of the Sun” - our Russian Maslenitsa, which is now tied to Cheese Week, before the “baptism of fire and sword” was celebrated on the Day of the Spring Equinox.

Proverbs and sayings related to the spring equinox

"On Soroka, day and night are measured."
“The equinox shows light in spring, twilight in autumn.”

Orbital point of the Earth's vernal equinox

By definition, the equinox is a moment that is quite difficult to practically establish with great accuracy (and, as a result, expensive), so it is determined by calculation, and clarifying measurements are carried out directly at the equinox.
When making calculations, you can use the following signs of the spring equinox:

The angle between the direction to the center of the Sun (S spring O) and the line of the earth's axis (S spring N) is exactly 90° ();
- the plane passing through the center of the Sun and the axis of the Earth is inclined to the plane of the ecliptic 90°- ε = 90°- 23.44° = 66.56°,
- the line of intersection of the equatorial plane with the ecliptic plane coincides with the line connecting the center of the Sun and the center of the Earth (direction to the Sun - B 2 O, );
- the line connecting the center of the Sun and the center of the Earth passes through the equator.

In Figure 1, it is no coincidence that the semi-axis of the Earth's orbit - line A 1 O is depicted noticeably smaller than the semi-axis OA 2. This is true - the Earth's orbit is currently elongated towards the summer solstice point.
As a result, the time interval from the moment of the spring equinox to the autumn one is longer than from the autumn equinox to the spring one by 7 days 13 hours 21 minutes (March 2020 - September 2020 interval is 186.4 days and September 2020 - March 2021 interval is 178.84 days). The average difference in equinox intervals for this century is 7 days. 13:37

The vernal equinox
Observation from Earth

Sergey Ov

On the day of the equinox, the Sun rises almost exactly in the east and sets almost exactly in the west, and if you measure the angle of maximum elevation of the Sun h sun, then you can easily determine the latitude of the area φ = 90° -h sun.

Earth at the vernal equinox
View from near-Earth space

Earth at the vernal equinox, tilt of the earth's axis (big picture)
Sergey Ov

Designations:
B 2 B 1 - line connecting the center of the Sun and the center of the Earth - direction to the Sun;
S vernal - orbital point of the vernal equinox in this moment coincides with the center of the Earth;
S spring N - line of the earth's axis;
∠CS spring N - angle of inclination of the earth’s axis ε = 23.44° (23.4392811° ± 0.0047222°);
∠CS spring O - the angle between the direction to the Sun and the plane of the earth's axis;
d is the angle of incidence of sunlight at the equator at noon (Sun at zenith).

At point S, the plane of the earth's axis perpendicular to the ecliptic also forms a right angle with the direction to the Sun

Sergey Ov(Seosnews9)

1. Equinox- the moment in time at which the center of the solar disk, during its apparent annual movement along the ecliptic, crosses the celestial equator. On the days of the equinoxes, the length of the day on the entire Earth, excluding the regions of the earth's poles, is almost equal to the length of the night, differing from 12 hours only by a few minutes due to refraction and the significant angular diameter of the Sun. The point at which the center of the Sun crosses the equator when moving from the Southern Hemisphere to the Northern Hemisphere is called the vernal equinox, and the opposite point is the vernal equinox.

Big Soviet Encyclopedia, 3rd ed. 1969 - 1978

2. Celestial equator- the great circle of the celestial sphere, the plane of which is perpendicular to the axis of the world, is a projection of the plane of the earth's equator onto the celestial (stellar) sphere. The celestial equator divides the stellar sphere into the Northern and Southern Hemispheres, the poles of which are called, respectively, the celestial poles. The constellations onto which the celestial equator is projected are called equatorial.

3. Ecliptic- trajectories of the annual movement of the Sun visible from the Earth. The plane of the ecliptic coincides with the plane of the Earth's orbit