Duration of day and night on June 22. Day of the winter solstice among the ancient Slavs

What are the names of the days of March 21, June 22, September 23 and December 22? What is the length of day and night these days? Where and when does the Sun rise and set on these days? What part of the earth's surface midday sun these days is at its zenith?

Answer

March 21 - the day of the spring equinox: astronomical spring is coming. At this time, throughout the Northern Hemisphere, except for areas located near the poles, the duration of day and night is 12 hours. The sun rises exactly in the east at 6 o'clock and sets exactly in the west at 18 o'clock. At the equator at noon on March 21, the Sun is at its zenith, that is, at a point located above the observer's head.

June 22 - Summer Solstice: spring ends, astronomical summer begins. On this day, the northern end of the earth's axis is tilted towards the Sun, the Sun at noon is at its zenith above the Tropic of Cancer. Tropics (Greek - "turning circle") are imaginary circles on the surface of the Earth, located at the same distance north and south of the equator. On the day of the summer solstice, the Sun does not set below the horizon north of the line, which is called the Arctic Circle.

September 23 is the autumnal equinox astronomical summer ends and autumn begins. On the whole Earth, except for the poles, the duration of day and night is 12 hours. The sun rises at 6 o'clock in the east and sets exactly in the west at 18 o'clock. At noon, the Sun is at its zenith at the equator.

December 22 - winter solstice autumn ends and astronomical winter sets in. On the day of the winter solstice, the northern end of the earth's axis is tilted away from the Sun, the sun's rays fall vertically on the lines of the Southern Tropic (Tropic of Capricorn), and on the line of the Antarctic Circle the Sun does not set beyond the horizon.

On December 22, 2011 at 2:30 pm fraternal time (UTC+9h) the Sun will descend to the maximum in the southern hemisphere of the sky, that is, moving along the ecliptic, it will reach its lowest declination -23° 26.457 minutes. In astronomy, the moment of the winter solstice is taken as the beginning of winter. The astronomical longitude of the Sun at this moment is 90° (located in the constellation Sagittarius). After December 22, the Sun gradually, at first hardly noticeable, will begin to add height until the day of the summer solstice.

In Bratsk, all week near the winter solstice, the Sun rises above the horizon to a height of 10 °. On these days, in the northern hemisphere of the Earth, the Sun remains least of all above the horizon. December 21 and 22 are the shortest days of the year. From 21 to 22 December - the longest night. In Bratsk, the length of daylight hours on the winter solstice will be 6 hours 52 minutes.

Sunrise on this day at 10 hours 45 minutes and sunset - 17 hours 37 minutes.

During the winter solstice, the Sun does not rise at all above a latitude of 66.5 degrees, and the night lasts around the clock. Only twilight at these latitudes suggests that the Sun is somewhere below the horizon in the middle of the twilight segment. At the North Pole of the Earth, not only the Sun, but also twilight is not visible, so the direction to the Sun can only be found by the constellations (it will be located below the constellation Hercules).

Why is this event so called? The fact is that the sun practically does not change its declination for several days before and after the winter solstice, as if “standing” at the same midday height. The solstice or solstice is marked by a folk sign: sun - for summer, winter - for frost. Indeed, from that moment on, the snow cover for the modern climate is just beginning to be established, although the Sun is sinking deeper and deeper into the southern hemisphere of the sky.

The shortest days are on December 21 and 22. In the first days after December 22, the day increases, but shifts to a later time on the clock. People say: "The day grows with the evening." Why is this happening?

The reason lies in the uneven increase in the direct ascension of the Sun during the year. In winter, the Earth is closer to the Sun and the speed of its movement in orbit is greater. Therefore, in winter angular velocity the movement of the Sun along the ecliptic is 3.4% more than the average.

22 10:45 14:11 17:37 +10° 32’31” 17:57.3 -23°26’

The winter solstice has occupied an important place in culture since at least the Neolithic. It is believed that this is proved by the surviving archaeological sites - such as, for example, Stonehenge in England and Newgrange in Ireland. The main axis of both structures indicates the point of sunrise (Newgrange) or sunset (Stonehenge) of the Sun on the day of the winter solstice.

Druids gathered at Stonehenge in England

Photo by Matt Cardy/Getty Images Europe

The solstice has long been celebrated by all peoples and is the basis of many religious holidays, including Christmas and the birth of Mithras. People gave the fiery holiday with bonfires, candles and fiery snakes a symbolic meaning. It was believed that such a holiday would help the Sun to overcome the border and lengthen the day. The ancient Slavs also celebrated the days of the solstice and equinox. These days (two solstices and two equinoxes - Kolyada, Velikden, Kupala and Ovsen - Tausen) served as starting points for farming, construction, and other vital matters for society. These days, in addition to the exact date, also have their own “week” (Rusalia, Carols and others).

On the days around the solstice, the declination of the Sun changes very slowly. In the first seven days after the solstice, the increase in declination "does not compensate" for the shift in sunrise and sunset to later times on the clock. Therefore, it turns out that "the day grows with the evening."

SUN DECEMBER 2011 Bratsk (Irk. region)

date Sun VC Zach VC° diam. short (0 hours places)

19 10:43 14:09 17:36 +10° 32’30” 17:44.0 -23°23’
20 10:43 14:10 17:36 +10° 32’31” 17:48.4 -23°25’
21 10:44 14:10 17:36 +10° 32’31” 17:52.9 -23°26’
22 10:45 14:11 17:37 +10° 32’31” 17:57.3 -23°26’
23 10:45 14:11 17:37 +10° 32’31” 18:01.8 -23°26’
24 10:45 14:12 17:38 +10° 32’31” 18:06.2 -23°26’
25 10:46 14:12 17:39 +10° 32’31” 18:10.6 -23°25’

And one more thing: the moment of the solstice shifts every year, since the duration of the solar year does not coincide with the calendar time. So, last year the winter solstice occurred on December 21 at 23.38 UTC. This is because the duration of the solar year is about 365 days 6 hours. For four years, a whole day is accumulated and they are added in a leap year, February 29, to compensate for this offset.

The summer solstice is one of the notable, turning points of the year. Since ancient times, all the peoples of the Earth have celebrated the holiday of the peak of summer at the end of June. common features celebration is the stacking of bonfires, divination. This day had a special meaning in the ancient religions of many nations around the planet. Structures that make it possible to distinguish this day from other days according to the position of the Sun during the summer solstice are considered the oldest astronomical observatories and date back thousands of years.

For several days before and after the moment of the solstice, the Sun almost does not change its declination, its midday heights in the sky are almost unchanged (the height changes during the year according to a schedule close to a sinusoid); hence the very name of the solstice. From observations of the heights of the Sun during both solstices, the inclination of the plane of the ecliptic to the plane of the celestial equator can be determined.

On June 22, 2011, at 2:15 AM Fraternal Time, the Sun, moving along the ecliptic, will reach its greatest declination and astronomical summer will begin. In Bratsk, the Sun rises above the horizon to a height of more than 57 degrees. During the summer solstice in the northern hemisphere of the Earth, the Sun remains above the horizon for the longest time. 21 and 22 June - the most long days in a year. From 21 to 22 June - the shortest night. The longitude of the day at the latitude of Bratsk reaches 17 hours 41 minutes, and navigational twilight does not end at all.

Solstice - an astronomical phenomenon, which is the moment of intersection with the center of the Sun of the points of the ecliptic, the most distant from the equator of the celestial sphere (solstice points), or, in other words, the moment in the annual rotation of the Earth around the Sun, when the shortest day or the shortest night is observed.

There are two solstices in a year - winter and summer. In the northern hemisphere, the winter solstice occurs on December 21 or 22, and then the shortest day (and the longest night) is observed, and the summer solstice occurs on June 20 or 21, and then the shortest night (and the longest day) is observed. In the southern hemisphere, these dates fall, respectively, on the summer and winter solstices.

In mid-latitudes, during the year in spring and early summer, the Sun rises higher and higher above the horizon every day, and at the time of the summer solstice it stops and reverses its movement. Then it rises lower every day and finally, at the time of the winter solstice, reverses its movement again and begins to rise.

At the moments of the solstices, the Sun in its apparent movement along the ecliptic moves farthest from the celestial equator, reaches its greatest declination, northern or southern. Due to the leap year shift in the date of the solstice in different years may vary by 1-2 days. In astronomy, the moment of the winter solstice is taken as the beginning of winter, and the moment of the summer solstice is taken as the beginning of summer. The astronomical longitude of the sun at these moments is 90° and 270°, respectively.

During the summer solstice, the Sun does not set above the latitude of 66.5 degrees at all, and the day lasts around the clock. This remarkable phenomenon allows the inhabitants of the northern strip of Russia to do without artificial lighting, practically around the clock. At the North Pole of the Earth, the Sun moves across the sky at the same height around the clock. In such a situation, it is very difficult to determine the time.

At other latitudes, the height of the maximum height of the Sun above the horizon can be calculated by the formula: Sun height \u003d 90 - latitude of the point + 23.5 (in degrees).

During the summer solstice, the Earth, as a result of the inclination of its axis to the plane of the ecliptic by 23 degrees, faces the Sun with its north pole. At the south pole at this time there is a polar night. There is a polar day at the north pole and circumpolar regions, which can be seen by rising above the Earth's pole and looking at the Earth from space.

June is the most unfavorable month for observations of faint objects, since the sky background remains bright even when the Sun is at its deepest below the horizon. However, this is the most favorable period for observing noctilucent clouds, which are precisely visible against the background of the twilight segment. But since mid-July, astronomy lovers can fully observe the sky during the greatest immersion of the Sun under the horizon.

As you know, the Earth revolves in its orbit around the Sun. For us, people on the surface of the Earth, such an annual movement of the Earth around the Sun is noticeable in the form of an annual movement of the Sun against the background of stars. As we already know, the path of the Sun among the stars is a great circle of the celestial sphere and is called the ecliptic. This means that the ecliptic is a celestial reflection of the Earth's orbit, so the plane of the Earth's orbit is also called the plane of the ecliptic. The axis of rotation of the Earth is not perpendicular to the plane of the ecliptic, but deviates from the perpendicular by an angle. Due to this, the seasons change on Earth (see Fig. 12). Accordingly, the plane of the earth's equator is inclined at the same angle to the plane of the ecliptic. The line of intersection of the plane of the earth's equator and the plane of the ecliptic retains (if precession is not taken into account) an unchanged position in space. One end points to the vernal equinox, the other to the autumn equinox. These points are fixed relative to the stars (up to precessional motion!) and together with them participate in the daily rotation. Near March 21 and September 23, the Earth is located relative to the Sun in such a way that the boundary of light and shadow on the Earth's surface passes through the poles. And since each point on the surface of the Earth makes a daily movement around the earth's axis, then exactly half of the day it will be on the illuminated part of the globe, and the second half on the shaded one. Thus, on these dates, the day equals the night, and they are called the days of the spring and autumn equinoxes, respectively. The earth at this time is on the line of intersection of the planes of the equator and the ecliptic, i.e., at the points of the spring and autumn equinoxes, respectively. We single out two more special points in the Earth's orbit, which are called solstices, and the dates on which the Earth passes through these points are called solstices. At the point of the summer solstice, at which the Earth is near June 22 (summer solstice day), the north pole of the Earth is pointing towards the Sun, and most days, any point in the northern hemisphere is illuminated by the Sun, that is, on this date the day is the longest of the year. At the point of the winter solstice, at which the Earth is near December 22 (winter solstice), the north pole of the Earth is directed away from the Sun, and most of the day any point of the northern hemisphere is in the shade, i.e. on this date the night is the longest per year, and the day is the shortest. Due to the fact that the calendar year does not coincide in duration with the period of revolution of the Earth around the Sun, the days of equinoxes and solstices in different years may fall on different days (one day from the dates mentioned above). However, in the future, when solving problems, we will neglect this and assume that the days of equinoxes and solstices always fall on the dates indicated above.

As you know, the Earth revolves in its orbit around the Sun. For us, people on the surface of the Earth, such an annual movement of the Earth around the Sun is noticeable in the form of an annual movement of the Sun against the background of stars. As we already know, the path of the Sun among the stars is a great circle of the celestial sphere and is called the ecliptic. This means that the ecliptic is a celestial reflection of the Earth's orbit, so the plane of the Earth's orbit is also called the plane of the ecliptic. The axis of rotation of the Earth is not perpendicular to the plane of the ecliptic, but deviates from the perpendicular by an angle. Due to this, the seasons change on Earth (see Fig. 12). Accordingly, the plane of the earth's equator is inclined at the same angle to the plane of the ecliptic. The line of intersection of the plane of the earth's equator and the plane of the ecliptic retains (if precession is not taken into account) an unchanged position in space. One end points to the vernal equinox, the other to the autumn equinox. These points are fixed relative to the stars (up to precessional motion!) and together with them participate in the daily rotation.

Near March 21 and September 23, the Earth is located relative to the Sun in such a way that the boundary of light and shadow on the Earth's surface passes through the poles. And since each point on the surface of the Earth makes a daily movement around the earth's axis, then exactly half of the day it will be on the illuminated part of the globe, and the second half on the shaded one. Thus, on these dates, the day equals the night, and they are called the days of the spring and autumn equinoxes, respectively. The earth at this time is on the line of intersection of the planes of the equator and the ecliptic, i.e., at the points of the spring and autumn equinoxes, respectively.

We single out two more special points in the Earth's orbit, which are called solstices, and the dates on which the Earth passes through these points are called solstices.

At the point of the summer solstice, at which the Earth is near June 22 (summer solstice), the north pole of the Earth is directed towards the Sun, and for most of the day any point in the northern hemisphere is illuminated by the Sun, i.e. on this date the day is the longest in the year .

At the point of the winter solstice, at which the Earth is near December 22 (winter solstice), the north pole of the Earth is directed away from the Sun, and most of the day any point of the northern hemisphere is in the shade, i.e. on this date the night is the longest per year, and the day is the shortest.

Due to the fact that the calendar year does not coincide in duration with the period of revolution of the Earth around the Sun, the days of equinoxes and solstices in different years may fall on different days (one day from the dates mentioned above). However, in the future, when solving problems, we will neglect this and assume that the days of equinoxes and solstices always fall on the dates indicated above.