Why does day give way to night? How to explain to a child why day follows night

Earth is one of the planets solar system. The planet Mercury is closest to the Sun. Next are the planets Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. The planets circle the Sun in different time: the farther a planet is from the Sun, the longer its path around it, and the longer the year lasts on the planet.

On Earth, the sun rises in the east in the morning, travels through a semicircle during the day, and disappears in the west in the evening. In fact, the Earth rotates, rotating around its axis, like a children's toy spinning top.

During the day the sky is blue and in the evening it is black. Why does the time of day change? As the Earth rotates, it exposes the sun to one side and then the other. The hemisphere facing the Sun has daylight because it receives light from the Sun. It is night on the opposite hemisphere and is not illuminated by the Sun.

Mercury makes a complete revolution around its axis in 58.65 days, and around the Sun in 88 days. There are 176 days of solar days on Mercury. On Venus, the change of day and night occurs in 117 days, day and night there last 58.5 days, a year on Venus is 243.2 days. The daily rotation of the Earth occurs in 23 hours 56 minutes 4.1 seconds. that is, in one sunny day. The Earth's daily rotation axis is directed towards the alpha star Ursa Minor, which is called Polar. On Mars, a day lasts 24 hours 39 minutes 35 seconds. The Martian year lasts 686.9 days. The period of rotation of Jupiter, the largest planet, around its axis is the shortest of all the planets. At the equator - 9 hours 50 minutes 30 seconds, in mid-latitudes - 9 hours 55 minutes 40 seconds. This means that day and night there are equal to 4 lessons at school.

Full daylight

Read the text and answer the questions.

Full daylight June 22, 2002

While the Northern Hemisphere will celebrate its longest day on June 22, 2002, Australia will have its shortest.
On this day in Melbourne, Australia, the Sun will rise at 7:36 am and set at 5:08 pm, and the duration of the full daylight hours will be 9 hours 32 minutes.
This same year, the longest day in Australia will be on December 22. The sun on this day will rise at 5 hours 55 minutes and set at 20 hours 42 minutes, and the duration of full daylight will be 14 hours 47 minutes.
The President of the Astronomical Society, Mr. Perry Vlahos, explained that the existence of seasons in the Northern and Southern Hemispheres was associated with the tilt of the Earth's axis by 23 degrees.

Question 1. Which statement explains the cycle of day and night on Earth?

Solution. The change of day and night on Earth is caused by the fact that our planet alternately turns to the Sun, first on one side, then on the other: while one half of the planet is illuminated, the other half is in shadow. The change of day and night will be observed on the planet if it rotates around its axis or orbits a star. If, as, for example, for the Earth, there is a simultaneous rotation around its axis and rotation around the Sun, then the change of day and night will be observed only if the rotation frequencies do not coincide. (If the frequencies were the same, the Earth would always be turned to the Sun with one side, as, for example, the Moon is turned to the Earth.) The change of day and night on Earth is caused by the simultaneous participation of our planet in two movements - rotation around its axis and rotation around the Sun - with different frequencies.
Correct answer: absent.

Question 2. The earth is illuminated by the sun's rays, as shown in the figure.

Let's assume that in Melbourne this moment the shortest day of the year. Draw the earth's axis, the equator in the figure and indicate the Northern and Southern Hemispheres.

Why does the cycle of day and night occur on Earth?

Label them or make the necessary inscriptions.
Solution. Melbourne is located in the Southern Hemisphere. If Melbourne is currently experiencing the shortest day of the year, it means it is winter in the Southern Hemisphere and summer in the Northern Hemisphere. The Earth is currently facing the Sun North Pole, and the Earth's rotation axis lies in the plane of the figure. The picture will be as follows:

Correct answer: see picture.

Why is there day and night?

Consequently, the sun's rays fall on one side or the other earth's surface. On the side facing the Sun we have day, on the opposite side we have night. This is how the change of day and night occurs.

What explains the change of seasons? This is due to the movement of the Earth around the Sun.

We have seen that the sun's rays bring not only light to the Earth, but also heat. We have also already said that the more vertically the rays fall on the earth’s surface, the greater their intensity. In summer, especially at noon, the Sun stands higher and remains above the horizon for a longer time than in winter; In this case, the sun's rays fall more vertically and heat the Earth's surface more strongly. In the evening and morning the Sun is low above the horizon, its rays fall obliquely and are less intense.

Throughout the entire time the Earth moves around the Sun, its axis of rotation constantly maintains the same direction in relation to the plane of the Earth’s orbit - it is inclined to it at a certain angle (Fig. 19). As a result, at different positions of the Earth in orbit, one or the other hemisphere of the Earth receives either more or less solar heat and light.

When the northern hemisphere receives more heat and light, when the days are longer here, we have summer, and in the southern hemisphere we have winter. When winter begins in our country, summer begins in the southern hemisphere. This is how alternation occurs, the change of seasons.

At the north and south poles of the Earth, day and night alternately last for six months. The sun does not set on one pole for six months. The rays sent by it fall obliquely, as if sliding along the earth's surface. We

Rice. 19. The inclination of the earth’s axis to the rays of the Sun at different times of the year

we have a continuous day. For the next six months, the same thing happens at the other pole.

Twice a year the Earth is in such a position relative to the Sun that its surface facing it is illuminated completely from the north to the south pole. At this time, all over the globe, day is equal to night. These are the days of the spring (March 21) and autumn (September 23) equinoxes.

Category: Sun

Changes in the inclination of the sun's rays and the length of the day at different latitudes. Belts of illumination. Change of seasons. Annual rhythm in the geographic envelope.

Tropical year– the time interval between two passages of the Sun through a point spring equinox. Shorter than stellar at 20 m 24 s, because The point of the vernal equinox moves towards the annual movement of the Sun. This phenomenon is called precession - the movement of the axis of rotation. Z. around the perpendicular to the plane of rotation. with the apex in the center of the west, in which the axis describes a circular conical surface (precession period -26,000 years).

Lighting belts, astronomical thermal belts.

Hot belt– located between the tropics, the Sun is at its zenith twice a year at noon.

Two temperate zones – between the tropics and polar circles. The sun is never at its zenith; the length of day and night and the height of the sun above the horizon vary greatly throughout the year. During the day there is always a change of day and night.

Two cold belts– between the polar circles and the poles. There are polar days and nights here (the Sun either does not appear above the horizon or does not fall below it).

The change of seasons determines the annual rhythm in geography. shell. In the hot zone, the annual rhythm depends on changes. humidified, moderate - depending on temperature, cold - depending on lighting conditions.

Z. rotation from west to east counterclockwise, perfect.

turnover per day. Angle by which the displacement. point on the earth's surface, for all latitudes is 150 in 1 hour. Linear speed, path traversable by point in units time depends on the latitude of the place. The geographic poles do not rotate; the speed there is zero. The speed on one meridian is different, on the same parallel it is the same.
14. Axial rotation of the Earth and its consequences. Axial rotation speed. Geographic poles, equator, parallels, meridians. Axial rotation of the Earth: direction, angular and linear speeds, evidence of rotation.

It moves along the third orbit from the Sun, 934 million km long, at a speed of 29.8 km/s, counterclockwise, and motion occurs in the same direction. Z. around its axis.

Georaph. consequence annual movement Earth - changing seasons, changes. will continue. day and night, the formation of light zones, the annual rhythm in geographical envelope.

Z. rotation from west to east counterclockwise, perfect. turnover per day. Angle by which the displacement. point on the earth's surface, for all latitudes is 150 in 1 hour. Linear speed, the path traveled by a point in units. time depends on the latitude of the place. The geographic poles do not rotate; the speed there is zero. The speed on one meridian is different, on the same parallel it is the same.

The earth rotates around an axis from west to east, i.e.

Tip 1: Why does day give way to night, and summer to winter?

counterclock-wise. In this case, the angular speed of rotation, i.e. the angle through which any point on the Earth’s surface rotates, is the same and amounts to 15° per hour. Linear speed depends on latitude: at the equator it is highest - 464 m/s, and the geographic poles are stationary.

Geographic pole- the point at which the Earth's axis of rotation intersects the Earth's surface. There are two geographical poles: the North Pole - located in the Arctic (the central part of the North Arctic Ocean) And South Pole- is located in Antarctica.

All meridians converge at the geographic pole, so the geographic pole has no longitude. The north pole has a latitude of +90 degrees, and the south pole has a latitude of −90 degrees.

There are no cardinal directions at the geographic poles. There is no change of day and night at the poles, since the poles do not participate in the daily rotation of the Earth.

At the geographic pole, the angle of elevation of the Sun does not exceed 23.5°, which is why the temperature at the pole is very low.

The position of the geographic poles is conditional, since the instantaneous axis of rotation of the Earth moves. Because of this, the geographic poles move by several meters per year.

Equator- an imaginary line of intersection with the surface of the Earth of a plane perpendicular to the axis of rotation of the planet and passing through its center. Its length is approximately 40075 km.

Parallel- line of section of the surface of the planet by a plane parallel to the equatorial plane.

On the globe, a parallel is drawn in the form of a circle, all points of which are equidistant from the equator. All points of the same parallel have the same latitude, but different longitude. The lengths of the parallels are different: they increase as they approach the equator and decrease as they approach the poles. The equator is the most long parallel. To calculate the length of one degree of arc of an arbitrary parallel on Earth, you can multiply 111.3 km (the length of the arc of the equatorial parallel of 1 degree) by the cosine of the angle corresponding geographical latitude the desired parallel.

Length of one degree of parallel arcs

0° – 111.3 km

10° – 109.6 km

20° – 104.6 km

30° – 96.5 km

40° – 85.3 km

50° – 71.1 km

60° – 55.8 km

70° – 38.2 km

80° – 19.8 km

Meridian- half of the surface section line globe a plane drawn through any point on the earth's surface and the axis of rotation of the earth. Each meridian intersects with all the others at two points: at the North and South Poles. The length of each meridian on the globe is 20,004,276 m. All points of one meridian have the same longitude, but different latitude. Greenwich is taken as the prime meridian. Magnetic meridian- power line projection magnetic field celestial body on its surface

The day is sidereal - sunny. Time: true solar, average solar (local), zone, maternity leave, summer. Universal time. Date line. The change of night and day. Daily rhythm in the geographic envelope.

Sidereal day– the time interval between the two upper culminations of the stars = 23 hours 56 m 4s.

True solar days– the period of time between two culminations of the center of the Sun; the lower culmination – midnight – is taken as the beginning of the day.

Avg. solar time – average duration solar day = 24 hours.

Equation of time– difference between true and average. time.

Local time– average solar time at each meridian. 15 0 =1 hour. The entire surface of the Earth is divided into 24 belts of 15 0 each.

World Time– mean solar time at the Greenwich meridian, which is considered the prime meridian.

Date line– a conditional line used to delimit places that at the same point in time have different calendar dates. Meridian = 180 0, in Chukotka deviating to the east. When crossing a line from west to east, one day is subtracted, when crossing from east to west, one day is added.

Standard Time – the time of each time zone, determined by the central meridian.

T n -T m =N-l,

Tn – standard time

Tm- local time

N– belt number

l– longitude of the place in hourly terms (lambda).

Maternity time– standard time of each time zone + 1 hour.

MOSCOW TIME - maternity time second time zone.

Summer time- used in many countries for rational purposes.

use of el. in the summer months, change the time 1 hour forward (d/n +2).

The change of day and night creates a daily rhythm in the geographic shell, which manifests itself in living and nonliving nature.

Please tell me where the windows of your house face?

Does the sun wake you up in the morning, breaking 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 picture of sunrise and sunset that we know 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 meeting the sun at dawn and seeing it off at sunset occurs regularly twice a day - in the morning and in the evening.

Example: Move your mouse across the image from left to right.

A little complicated?
Then here: Time of day for children +3 to >7

What is the time of day?

A day is a cycle of time during which the sun, rising from the east, passes across the sky and sets in the west, then, when night falls on our half of the earth, the sun makes a revolution from the other part of the planet and rises again from the east.

A day lasts exactly 24 hours. Each hour consists of 60 minutes. Every minute of 60 seconds. Accordingly, a day = 24 hours = 1440 minutes = 86,400 seconds. For convenience of notation of time, 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 from 12 hours 00 minutes to 11 hours 59 minutes (p.m.). This time format is established in England, Ireland, France, Greece, Turkey, and is also used in Australia, Canada, the USA and the Philippines.
24 hour time format- from 0 hours 00 minutes to 23 hours 59 minutes. The most common time format used in Russia and many other countries of the world.

How does the change of day and night occur on earth?

In addition to the rotation of the earth around the sun (calendar year), the globe rotates on its axis. A complete revolution around its axis occurs in 24 hours, which are called days.

At the same time, being on the surface of the Earth, we do not feel the movement of the globe, but can only observe it based on the apparent movement of the sun and 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 sun rising over the horizon.
Day- the movement of the sun across the sky from east to west.
Evening- sunset in the western sky and the 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 the night is still lasting 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 was uniform, however, later scientists calculated the inaccuracies and it turned out that unevenness in rotation was still present. These irregularities are associated with a slight oscillation of the globe during rotation (conventionally, the rocking 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 compiling the calendar.

Changing the time of day

Many photographers tried to capture the change of day and night. By taking many pictures in a row from one position, it was possible to trace the smooth movement of the sun across the sky, see the movement of the stars, and get beautiful videos of sunrise and sunset. Features of time-lapse photography are when a camera mounted on a tripod in a stationary position takes a series of photographs at certain intervals over a long period.

If the length of the day is constant, then the duration components The time of day changes depending on the time of year. This is due to the tilt of the earth and the movement around the sun along an elliptical path. So in summer, daylight lasts longer than night, and in winter, on the contrary, the night is longer than the day.

At the same time, in different parts Around 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 its “white nights”, the sun sets not far below the horizon and therefore the nights seem bright.

Different times of day look and feel different. This is connected with the biological (internal) clock by which a person is accustomed to living (day - wakefulness, night - sleep) and with the variety of color contrast, as well as with mood. By the morning, strength increases, the day is spent in study, business, work, and in the evening there is fatigue, a gradual withdrawal from work, rest and sleep.

The change in time of day was painted by the artist Nikolai Petrovich Krymov in an educational landscape entitled “Changes in the landscape in tone and color at different times of the day.”

For the landscape, a simple motif was chosen - a house near the forest, a diagonally leading path that gives volume to the picture, a field and the sky, sometimes people passing along the path came into view, which gave the picture life. 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 adapts to the rhythm of the changing time of day. In the morning the plants bloom, in the evening the buds close. The human world also adapts to the changing time of day. Most common work schedule, lesson schedule, work educational institutions and entertainment centers and even the radio and television program is compiled depending on the time of day.

Walk up to anyone you meet on the street and ask them to show in which direction the Earth rotates. 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.

There is hardly a person now who does not know about the rotation of the Earth. rises and sits on the rotation of the Earth and ensures the change of day and night. It’s very easy to understand this with the help of a globe and a table lamp, simulating that when the globe rotates, its sections will alternately go into the shadows and come out again into the light.

If you are in Russia, that is, in, and you 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 opposite direction visible movement Sun. If you were in the southern hemisphere and also watched the Sun, facing it, then for you it would move from right to left.

What determines the change of seasons? A combination of two factors: the movement of the Earth around the Sun and the tilt of the Earth’s axis relative 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 the southern and northern hemispheres of the Earth. When summer begins in the northern hemisphere, winter begins in the southern hemisphere. But six months will pass, and everything will change - the Sun will begin to warm up the southern hemisphere more, and summer will come there. In the north, winter will reign.

The tilt of the earth's axis also leads to the fact that the length 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 constant only at the equator and 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 for six months. For other territories, the length of 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 December 21, when the day is very short and the night is longest.

Video on the topic

Sources:

How does the day/night change occur?

Since ancient times, people have tried to understand and explain various natural phenomena– why it rains, why day turns 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 this is not true.

Instructions

The Earth's axis is an imaginary line connecting the North and South Pole. It has a certain angle of inclination to the orbital plane (ecliptic plane). The angle of inclination of the axis is constant and amounts to 23.5 degrees. The earth's axis is invariably directed to one point - to North Star. It is the presence of the angle of inclination of the planet’s axis to the plane of its orbit that determines the change of year.

Due to the angle of inclination of the earth's axis to the ecliptic plane, the same parts of the earth's surface at different times during its orbital movement are illuminated by the sun differently, that is, they receive different quantities warmth and light.

Part of the year is turned towards the Sun by the North Pole, the other part of the year - by the South Pole. That is, part of the year North hemisphere receives more heat and light and heats up more. In the territory located north of the equator, spring and summer replace the winter cold. The southern hemisphere is hidden from direct sunlight at this time. The sun's rays “sliding” along the surface of the Earth carry little heat, and autumn and winter begin south of the equator.

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 rest of the year), the South Pole turns out to be inclined towards the Sun. The southern hemisphere receives more warmth and light, and spring arrives south of the equator. The northern hemisphere, receiving less sunlight, is gradually cooling down. North of the equator it is winter.

The equatorial zone of the Earth is constantly under direct sunlight, so there is no change of seasons at the equator.

Video on the topic

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how the seasons change

People are looking forward to summer, planning vacations, imagining how they will spend the warm summer money, but this time of year has its drawbacks and can be considered dangerous.

Instructions

Midges and mosquitoes literally haunt us in the summer. Of course, no one has ever suffered much from a mosquito bite, but midge bites can harm the body. A large bite from a small insect is not always safe; sometimes it can cause problems with blood circulation (this all depends on the human body); bites near the eyes are especially dangerous; here it is recommended to immediately consult a doctor. Such dangers include wasps, bumblebees, well-known ticks and other similar insects.

Children are little creatures who are always interested in everything. I offer you a small, easy at-home visual experience of why day follows night. Which the child can repeat on his own.

Children are little creatures who are always interested in everything. The child grows and asks the question why more and more often. Many parents have probably encountered similar questions: Why can’t it always be day? Why is it light during the day and dark at night? It’s still too early to explain from a scientific point of view; the child still won’t understand. I offer you a small, visual experience at home, why day follows night. First, you need to explain to the child that the earth rotates around its axis and this is very important. Because if it stops, then life on earth will stop, since on the one hand, in one hemisphere it will be terribly hot, and on the other hand, in the other hemisphere everything will freeze, since the sun’s rays will not reach there. Therefore, nature has such a pattern: the earth rotates around its axis and night follows day on earth. During the day everything warms up well, and at night it cools down a little. Therefore, people, animals, plants are not in danger and they can live and rejoice.

For our experiment we will need a long stick, a candle and a tangerine. It is advisable to conduct this experiment in the evening, at dusk, to make it more interesting.

Mandarin will play the role of our planet. In shape it is slightly similar to the earth, flattened on both sides, as if at the poles, and looks like an ellipse. We draw a small man in Mandarin, explaining to the child that this is the place where he is.

We light a candle, place it on the table, preferably on a special stand so that it is stable, and turn off the light. The candle is our Sun.

We carefully pierce the tangerine with a stick so as not to damage the segments; this will be our earth's axis.

We bring the tangerine to the candle; the flame illuminates only one side of the fruit, just as the sun illuminates one hemisphere. The stick can be slightly tilted, the earth's axis is also slightly tilted. The light falls on the drawn man, which means it’s day here, and where it’s dark it’s night. Then we turn the stick with the tangerine so that the other half of the tangerine is illuminated. It turns out that the tangerine, like the earth, rotates around its axis, and day gives way to night. If your child has a desire, you can let him carry out the experiment himself from beginning to end.

We explain to the child in a language he can understand that the earth spins on its axis, just like our mandarin. Therefore, on our planet, it falls sunlight, then no. The mandarin, spinning on a stick, turned around its axis and the light from the candle first fell on one half, then on the other. When the light fell on the little man, it was day, and when it fell on the other side, the little man had night.