For the inhabitants of the Earth, the constant change of day and night is a common occurrence. All life on the planet is subject to the rhythmic alternation of dark and daylight hours. However, this does not happen on all planets. For example, on Venus, which rotates very slowly around its axis, the year lasts less than two Venusian days. Jupiter rotates on its axis in about five Earth hours, and Saturn in ten.
The Earth makes a full rotation around its axis in 23 hours 56 minutes 4.1 seconds, the day during this time is replaced by night - a sidereal day passes. A sidereal day is understood as the time of a complete revolution of our planet around an axis relative to the stars, considering them infinitely distant.
The alternation of day and night creates favorable conditions for all life on Earth. As you know, the Earth has the shape of a ball, and the axis of its rotation is constantly inclined to the plane of the orbit at an angle of 66°33`22″. Because of this, the sun's rays illuminate different parts of the earth's surface differently, and therefore the length of day and night is different everywhere. It depends on geographic latitude and time of year.
Only twice a year - on the days of the spring and autumn equinoxes (March 20-21 and September 23), the length of day and night is the same at all latitudes of the Earth and is equal to 12 hours. The sun at this time is at its zenith above the equator, and the terminator - the line separating light and shadow on the planet's surface - passes through the poles, coinciding with the direction of the meridians. The sun's rays fall on the equator these days at an angle of 90 °, and the Northern and Southern hemispheres are heated evenly.
On the days of the summer and winter solstices (June 22 and December 22), the planet has the longest night and the shortest day. For example, on June 22, the Sun is at its zenith over the Tropic of the North (23°07`N). In the Northern Hemisphere on this day at all latitudes, the day is longer than the night. To the north of the Arctic Circle (66°33`N) the polar day is set - the Sun does not set below the horizon for days. In the Arctic Circle, the polar day lasts a day, and at the poles - up to six months. The southern hemisphere on June 22 is less illuminated than the northern one. Here, at all latitudes, the day is shorter than the night, and the polar night sets in in the southern polar region.
The earth moves around the sun, but the tilt of the planet's axis of rotation remains constant. Gradually, the height of the Sun above the horizon in the Northern Hemisphere decreases, the days become shorter and the nights longer. Finally, September 23 comes - the day of the autumn equinox, when the length of day and night is equal at all latitudes. From this point on, the Sun begins to illuminate the Southern Hemisphere more. On December 22, on the day of the winter solstice, the hemispheres seem to change places. On this day in the Southern Hemisphere at all latitudes, the day is longer than the night, and there is a polar day beyond the Antarctic Circle. At the same time, polar night reigns in the northern polar regions.
To the south and north of the polar circles in both hemispheres, white nights come. At this time, evening twilight turns into morning, and darkness does not come. Beyond the Arctic Circle, the white nights precede the polar day. At different latitudes, white nights differ in duration: for example, in St. Petersburg they last from June 11 to July 2, and in Arkhangelsk - from May 13 to July 30.
The satellite of our planet, the Moon, rotates around its axis at such a speed that when moving around the Earth, it is constantly turned to it with one side. If the Earth moved around the Sun in a similar way and was constantly turned to it on one side, the natural conditions on the planet would change enormously. One hemisphere of the Earth would be illuminated all year round, while the other would be constantly in the shade. The illuminated hemisphere would heat up to a temperature of more than 100 ° C, which means that all rivers, seas and oceans would evaporate. On the dark side of the planet, the temperature would be below -100 ° C, here all the water would turn into ice. At the border of light and shadow, due to large temperature differences, earthquakes and eruptions would rage, earthquakes and eruptions would occur.
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Can you tell me where the windows of your house face?
Does the sun wake you up in the morning, making its way through the window?
Or does the sun see off the evening with gentle rays, softly reflected in the windows of your house?
Of course, the familiar picture of sunrise and sunset depends on which side the windows of our house face. If you do not take into account cloudy weather when the sun is simply not visible, then the meeting of the sun at dawn and seeing it off at sunset occurs regularly twice a day - in the morning and in the evening.
Example: Move the mouse over the image from left to right.
A bit complicated?
Then here: Time of day for children +3 to> 7
What is time of day.
A day is a cycle of time during which the sun, rising from the east, passes through the sky and sets in the west, then, when night falls on our half of the earth, the sun passes a revolution from another part of the planet and rises again from the east.
A day is exactly 24 hours long. Each hour consists of 60 minutes. Every minute out of 60 seconds. Accordingly, a day = 24 hours = 1440 minutes = 86,400 seconds. For convenience, two formats are used:
- 12 hour time format- time until noon from 0 hours 00 minutes to 11 hours 59 minutes (a.m.) and afternoon time from 12:00 p.m. to 11:59 p.m. this time format is set in England, Ireland, France, Greece, Turkey, Australia, Canada, the USA and the Philippines are also used.
- 24 hour time format- from 0 hours 00 minutes to 23 hours 59 minutes. The most common time format used in Russia and in many other countries of the world.
How does day and night change on earth?
In addition to the rotation of the earth around the sun (calendar year), the globe rotates on its axis. A full rotation around its axis occurs in 24 hours, which is called a day.
At the same time, being on the surface of the Earth, we do not feel the movement of the globe, but we can only observe it, based on the apparent movement of the sun, stars, relative to the Earth.
Conventionally, the time of day is divided into several parts:
- Morning- begins with the dawn of the sky in its eastern part and the sunrise from behind the horizon.
- Day- the movement of the sun across the sky from east to west.
- Evening- sunset in the west of the sky and gradually fading colors of the sunset.
- Night- Night time. At this time, the sun passes on the other side of the globe relative to us.
Since the Earth consists of continents located on both sides of the globe, the time of day in each part of the Earth is different. So if it is still night in New York, then in London it is already morning, in Moscow it is midday, and in Petropavlovsk-Kamchatsky it is already evening.
Interestingly, until recently it was believed that the movement of the globe around its axis is uniform, however, later scientists calculated the inaccuracies and it turned out that the unevenness in rotation is still present. These irregularities are associated with a slight oscillation of the globe during rotation (conditionally swaying of the Earth, in terminology - nutation), but these changes are so small (less than 0.001 s) that they are not taken into account in the calendar.
Changing the time of day
A lot of photographers tried to capture the change of day and night. taking many shots in a row from one position, one could trace the smooth movement of the sun across the sky, see the movement of the stars, and get beautiful videos of sunrise and sunset. Time-lapse photography is when the camera is mounted on a tripod in a stationary position for a long period of time takes a series of photographs at certain intervals.
If the duration of the day is constant, then the duration of the constituent parts of the time of day varies depending on the time of year. This is due to the tilt of the earth and the movement around the sun in an ellipsoidal trajectory. So in the summer daylight hours last longer than the night, and in winter, on the contrary, the night is longer than the day.
At the same time, in different parts of the globe, the length of day and night is different. For example, in the Crimea it gets dark quickly in the summer, the night is dark, and in St. Petersburg June is famous for "white nights", the sun does not set far behind the horizon line and therefore the nights seem bright.
Different times of the day look and feel differently. This is connected with the biological (internal) clock by which a person is used to living (day - wakefulness, night - sleep) and with a variety of color contrast, as well as with mood. In the morning, strength is added, the day passes in study, business, work, and in the evening fatigue, a gradual departure from business, rest and sleep.
The change of time of day was drawn by the artist Nikolai Petrovich Krymov in a study landscape called "Change in the landscape in tone and color at different times of the day."
A simple motif was chosen for the landscape - a house by the forest, a diagonally leading path that gives volume to the picture, a field and sky, sometimes people walking along the path came into view, which gave the picture liveliness. The landscape was captured 9 times at different times of the day, where the artist clearly showed how the landscape, colors and colors change at dawn in the morning, when the shadow from the sun moves during the day, at sunset in the evening and at night.
The entire plant and living world of nature adjusts to the rhythm of the change of time of day. In the morning the plants bloom, in the evening the buds close. The human world also adjusts to the change of time of day. The most common work schedule, class schedule, educational institutions and entertainment centers, and even the radio and television program is compiled depending on the time of day.
Every summer my nephew comes to visit us. He is still quite small, but terribly curious. Recently in the evening, when we were sitting in the yard and looking at the sunset sky, he asked me where the sun disappears and why it's getting dark. Lessons started popping up in my head astronomy, but everything seemed so complicated and incomprehensible that I myself could not imagine how it happens, let alone a small child. Then I seriously thought about how this can be explained.
Change of day and night on Earth
It's no secret that our planet revolves. It takes about 365 days for one rotation around the Sun, but if we talk about the Earth's own axis, then here it makes full turnover per day. A day is equal to twenty-four hours. If it is day at one point on the planet, then it will be night at the opposite point. The sun does not disappear anywhere, it remains in its place, but we are moving along with our planet. We do not catch this movement, because its speed is constant.
How was the change of day and night explained in ancient times?
There are various myths and legends about this:
Length of day and night on the days of the spring and autumn equinoxes
Day and night have different lengths depending on the season. In our country, the summer day lasts much longer than the night, and vice versa in winter. But there are days in the year when night equals day. Annually March 20 and September 22 or 23 The sun, passing from one hemisphere to another, passes through celestial equator, thanks to which we can trace such a phenomenon as an equinox.
Walk up to anyone you meet on the street and ask them to show you the direction in which the Earth is spinning. The question is very simple, but many people will answer it incorrectly. And all because they never tried to understand what is really happening with the movement of the Earth.
It is unlikely that now there will be a person who does not know about the rotation of the Earth. gets up, and sits down on, the rotation of the Earth and provides a change of day and night. It is very easy to understand this with the help of a globe and a table lamp that imitates - when the globe rotates, its sections will alternately go into the shadow and again come out into the light.
If you are in Russia, that is, in, and follow the movement of the Sun, then you will see that for you it moves from left to right (if you are facing it). But this movement of the Sun is illusory; in fact, the Earth rotates - in the direction opposite to the apparent movement of the Sun. If you were in and also followed the Sun, facing it, then for you it would move from right to left.
What determines the change of seasons? The combination of two factors: the movement of the Earth around the Sun and the inclination of the Earth's axis with respect to it by 23.4º. If the earth's axis were not tilted, there would be no change of seasons. It is the tilt of the earth's axis that leads to the fact that the Sun alternately warms up either the southern hemisphere of the Earth, or the northern hemisphere. When summer comes in the northern hemisphere, winter begins. But it will pass, and everything will change - the Sun will begin to warm the southern hemisphere more strongly, summer will come there. Winter will reign in the north.
The tilt of the earth's axis also leads to the fact that the duration of day and night in different parts of the world is not the same and changes as the earth moves around the sun. It is unchanged only at the poles: at the equator, day and night at any time of the year are equal to twelve hours; at the poles, day and night always last half a year. For other territories, the duration of the day and night smoothly changes from the summer solstice on June 21, when the day is maximum and the night is shortest, to the winter solstice on 21, when the day is very short and the night is the longest.
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- how does the day change
Since ancient times, people have tried to understand and explain various natural phenomena - why it rains, why the day changes into night, why the seasons change. But even now, some people think that the change of seasons is due to the distance of the Earth from the Sun. Actually it is not.
Instruction
Since the angle of inclination of the earth's axis does not change, then with the further movement of the planet in orbit (that is, the other part of the year), the South Pole turns out to be inclined towards the Sun. The southern hemisphere receives more heat and light, spring comes south of the equator. The northern hemisphere, receiving less sunlight, gradually cools. North of the equator is winter.
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- how does the season change
The alternation of day and night is so familiar to people that many do not even think about the cause of this phenomenon or its features. It is difficult to find a person who would not know about the rotation of the Earth or that it moves around the Sun. But how many people remember that day or night can last six months?
Every person who studied at school knows that the change of day and night is based on the daily rotation of the Earth. In 24 hours, it makes a complete revolution around its axis, which ensures the alternation of day and night for most regions of the Earth. For most - but not for all. The Earth is tilted in relation to the plane of its orbit by 23.4?. This leads to the fact that the Sun illuminates its surface unevenly. The territories near the North and South Poles find themselves in special lighting conditions: for six months at one of the poles reigns night, while on the other day. On one, the Sun simply does not set below the horizon, remaining in sight all the time, on the other, it does not appear above the horizon at all. White nights in St. Petersburg are connected precisely with the geographical position of the city - the sun does not go down too low, so night does not come. But the nights are not only in St. Petersburg, but also in all cities located above (closer to the North Pole) 49? northern latitude. At this latitude, day summer solstice is one white night. The closer from this latitude to the north, the more. From latitude 65? and to the north one can observe a continuous day The sun never sets below the horizon. Similar phenomena are observed on the other side of the equator. Why are the polar day and night last exactly six months? Because the Earth revolves around the Sun, and exactly six months later, due to the tilt of its axis, it exposes the Sun to another pole. The rotation of the Earth around the Sun and the tilt of the Earth's axis also explain the alternation of the seasons. Alternately, with a frequency of six months, the cold season is replaced by a warm one, and vice versa. When it's summer in the north, winter comes in the south. The easiest way to understand is by taking a globe and illuminating it with a lamp imitating the Sun. Rotating the globe, you can easily see how the alternation of day and night occurs. And moving the globe around the lamp, you will also understand the reasons for the alternation of the seasons. If you observe the Sun every day and mark exactly at the floor day its height above the horizon, you can see that it changes. Once a year - June 21st day summer solstice - it reaches its highest height. The duration of light in this day the largest, and night the shortest. Six months later, on December 21, in day winter solstice, the height of the Sun above the horizon will be the smallest, and day the shortest. For residents of the northern hemisphere, the summer solstice is day turn to winter. Every day the sun will rise above the horizon lower and lower until day the winter solstice will not reach its lowest point. From this moment, the turn to summer will begin - the Sun will rise higher and higher, its rays will fall on the earth at an ever more right angle, giving more heat.
It is traditionally believed that St. Petersburg is a city of bridges, palaces, canals, old mansions and white nights. The northern capital is also a city of tourists who are fed not only by impressions, but also by restaurants, bars, youth cafes, modern cinemas, and discos. Entertainment facilities work for them - billiard and tennis courts, bowling alleys. Peter has a huge number of establishments where you can celebrate a birthday for every taste.
Free, and in Japanese restaurants there is always the opportunity to order platter for the whole company of friends.
Check out one of the many nightclubs if you're more active. No wonder St. Petersburg is called the club capital of Russia: there are establishments of various kinds here. You will remember for a long time day held in the clubs "11", "Begemot", "Air", "Winter-Summer", "Jelsomino". Nightclub "Begemot" offers to dance all night long to the electronic music of the best DJs. "Winter-Summer" - an elite place for fashionable parties. Here you will be surprised by an exquisite menu and a very advantageous location - overlooking the water. Music Bar "11" is a luxury karaoke with an amazing interior and excellent cuisine, and in the club "Air" you can not only dance on three different dance floors, but also swim in the pool, play volleyball.
Head to one of the sports and entertainment centers if you want to combine your holiday with sports competitions. Bowling fans will surely like such clubs as Bowling City, Golden Strike, 7 Mile. Golden Strike has ten bowling lanes, four of which are aimed at children. In addition to seventeen bowling lanes, "7 Mile" has tables for American and Russian billiards, a bar, a cafe and a disco.
Rent one of the private boats if your day birth falls on the warm season (from May to October). Take a walk along canals and rivers, under numerous bridges. You can also go to the Gulf of Finland and continue the celebration there. However, it should be remembered that such a rest requires increased caution and attention. Head to the coast of the Gulf of Finland if you don't want to celebrate day birth in a stuffy city. From Sestroretsk to Zelenogorsk is located a large number of cozy restaurants and entertainment facilities. There you can take a large table on the open veranda, and then sunbathe on the sandy beach.
Sources:
- Internet guide to the stone jungle
Various ancient peoples, be it the Egyptians, Greeks or Romans, tried to explain all the phenomena occurring around them, so a fabulous explanation of the change of day and night has come down to our times. Legends of different nationalities are generally similar.
Change of day and night: a fabulous explanation
With the words "the sun has risen" or "the sun has set" we begin or end another day in life. Our ancestors endowed sunrises and sunsets with great power. These phenomena had a sacred meaning for our ancestors.
Indeed, during sunsets and dawns, various rituals and ceremonies, both church and magical, were performed. From here a fabulous explanation of the change of day and night “grew up”. Each user of social networks has a photo of sunset or dawn. Today, modern man does not understand these phenomena and does not know the sacred meaning.
ancient greek myth
The ancient Greeks have a fabulous explanation for the change of day and night. The titan Hyperion had three children: Selena, Eos and Helios. Shining with a cold light, Selene was the goddess of the moon. On her head was a sickle-moon. On the night road she rides in a chariot drawn by bulls. Selena leaves this road when her child stars fade and the marble columns turn pink.
Eos - the goddess of the morning dawn, announces the dawn of a new day. Following Eos, their brother Helios rushes from the east in a shining golden chariot. The Greeks revered him no less than the powerful and supreme Zeus. The rays of Helios penetrated into the most distant and dark corners through black clouds. Their warm light awakened all life. Thanks to the rays, trees and fruits grew. Helios is the storm of all criminals. The rays of this god blind them. Even the gods cannot hide from such rays.
Helios knows everything about the divine "affairs". It was he who suggested to Demeter that her daughter Persephone was kidnapped by Hades into his gloomy realm of shadows. But noon comes when Helios reaches the west. By evening, the horses of Helios and he himself get tired and blush. God goes to his palace for rest, where the divine retinue also rests, and Selena's chariot leaves for the road ... Such is the Greek change of day and night. Their fabulous explanation is similar to the Slavic myth.
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Slavic vision of day and night
The ideas about the world among the ancient pagan Slavs were very complex and confusing. The sun and sunlight were different concepts for them. For each season, the Slavs had a separate "sun" - Yarilo, Kupailo, Svetovit and Kolyada. They called the sun itself Horos. By the way, this word meant "circle". This is where the word round dance comes from.
Like the Greeks, the Slavic fairytale explanation of the change of day and night is simple - Dazhdbog (the sun - the giving god) rode a golden chariot across the daytime sky, harnessed by fiery winged horses. Morning and evening dawns were considered sisters. Moreover, the dawn was the wife of the sun. On the day of the summer solstice, the Slavs celebrated their wedding. Like the Greeks, the Sun is an all-seeing eye that watched everything and everyone. Because the criminals operate at night to this day.
Ancient Indian idea of the emergence of a new day
A distinctive Indian legend about the change of day and night. The fabulous explanation says that there was no night. She appeared thanks to one tragic incident. There was a brother Yama and a sister Yami. The brother died, and the lonely sister had no choice but to endlessly mourn the unfortunate brother. To all requests and exhortations to calm down and stop shedding tears, Yami only exclaimed: “But he died today!” The gods saw the truth: in order for the girl to calm down, a night is needed, only in this way will a new day come. They made the night. Morning came, Yami forgot about grief. And the Indians began to say "the sequence of day and night."
Conclusion
For many years our ancestors believed in these myths and legends about the creation of day and night, right up to the Middle Ages. Religion and mystical ideas were replaced by science. Nicolaus Copernicus 500 years ago wrote a book about how our planet rotates on its axis, orbiting around the star Sun. So, according to Copernicus, there was a change of day and night.
The fairytale explanation was destroyed. And the scientist's book was banned by the Pope, as it contradicted the Christian religion. Copernicus became famous as the creator of the heliocentric system. The name of this system comes from the name of the sun god Helios, so, according to the theory of Copernicus, the Sun is located in the center of the universe. The Polish astronomer died of a stroke on May 24, 1543, at the age of 73.
