The learned men of the 17th century must have been very surprised and experienced a lot of displeasure when they read Johannes Kepler’s book “The New Astronomy”. Of course, the German mathematician called for no less than the abandonment of the circular orbits in which the planets move, and replacing them with ellipses! Astronomers had not yet fully comprehended the revolutionary ideas of Copernicus, who placed the Sun at the center of the world and thus reduced the Earth to the status of an ordinary planet, when the second blow was dealt to the two-thousand-year-old system of the world of Ptolemy.
We can make a comparison with Mars, which has an imaginary rotation axis tilt of 25°, so close to the Earth's tilt value. While the Earth-Sun distance fluctuates only 4% throughout the year, for Mars the change is approximately 20%. Thus, on the red planet the influence of distance changes is much more accentuated than on our planet. Changes in solar system are huge, and we can imagine all sorts of situations: from an imaginary axis, an extremely sharp rotation inclination, like 98° in Uranus, to a distance like Pluto, which reaches 66%.
Ellipses! It's almost sacrilege! A circle is a perfect figure, and how else can bodies move in heavenly world, if not in circular orbits! But Kepler's theory explained the motion of planets better than any theory that used circular orbits. Based on it, it was possible to do more accurate predictions, where in the sky this or that planet will be in a year, ten, a hundred years. The theory worked!
A planet like Jupiter, which has a spin axis tilt of only 3° and a variation of 10% over distance, will have a larger effect initially due to distance than with respect to tilt. If the Earth had a different tilt or a more eccentric orbit, what might happen?
Using simple model described in section 2, it can be shown that if the Earth had an imaginary rotation axis tilted around 16°, the effects associated with the tilt and change orbital distance, would be of the same order. In this case climate change on our planet would be much weaker than the ones we have. On the other hand, if the difference between aphelion and perihelion were about 20%, we would also have a similar influence of the two factors, but in this case the south of the planet would have very cold winters and very hot summers, while in the north the variations would be very more pleasant than they actually are.
Earth, like other planets, also moves around the Sun not in a circular, but in an elliptical, elongated orbit. This means that our planet spends one part of its journey approaches the Sun, and the other part - deleted. The point where the Earth is closest to the star is called perihelion , and the point of the orbit farthest from the Sun is called aphelion . As a consequence, the size of the Sun in our sky should change.
This is because in summer summer The Earth will be much closer to the Sun than in the summer, as this closest approach occurs in January. In addition to these effects, when the Earth was at perihelion, solar tides could be much greater, more evaporation of water with a subsequent increase greenhouse effect, and it was also observed that the apparent angular diameter of the Sun would be larger.
Another approach to this question is to check the difference in sunlight between winter and summer due to the tilt of the Earth's imaginary axis of rotation. Thus, through simple calculations, it can be shown that the tilt of the imaginary axis, responsible for the difference in insolation, explains the observed seasons. For example, on the summer solstice, such as the Tropic of Capricorn, the rays strike almost perpendicular to the surface at noon. At the winter solstice, these same rays will strike at an angle of approximately 47°, resulting in approximately 32% less sunlight.
The difference in the size of the Sun when the Earth is at perihelion and at aphelion. Photo: Raffaele Esposito
Since the Earth moves in an ellipse, its motion unevenly. Due to the fact that the force of gravity decreases with increasing distance between gravitating bodies, near aphelion the Earth should move slower than at perihelion. Of course, this is reflected in the movement of the Sun across the sky: the luminary moves against the background of the stars, sometimes faster, sometimes slower (this does not mean the daily movement of the Sun from east to west, but the second, annual movement against the background of the constellations!). They must have different durations and seasons, because the season in which the Earth is closer to the Sun, our planet “skips” faster than others.
The development of this work was motivated by spontaneous concepts that rely on changes in the Earth-Sun distance to explain the phenomenon of seasons. The main proposal of this text was to show a counter-proof to this argument, that is, to calculate the effect of changing the Earth-Sun distance on the Earth to ensure that the temperature difference between winter and summer cannot be explained by this argument.
Seasons explained - one of best examples how in scientific teaching we still see a dogmatic approach to scientific knowledge in our schools. To materialize critical learning, it is important to place the student in the role of subject and take into account their prior or spontaneous knowledge. Thus, we believe that phenomena cannot be represented by ready-made and uncritical explanations.
All of the above are obvious consequences of Kepler's three laws, but in ordinary life they usually pass by our attention. And this is not surprising - the earth’s orbit is almost a circle, its elongation is small. Without making special observations, it is almost impossible to notice the effects of the Earth's motion along an ellipse.
This long preface was made in order to say the main thing: today, January 4, 2015, the Earth is at perihelion to the Sun - at the point of its orbit closest to the star. Exact date events - January 4 at 06:36 universal time, or at 09:36 Moscow time.
In the specific case of seasons, rigor suggests that initially both the inclination of the imaginary axis of rotation and the change in distance between the Earth and the Sun should play a role in the temperature of the planet. Students' ideas, often triggered by distorted pictures in textbooks, cannot simply be replaced by a simple and compelling explanation. It is necessary to present information and reasons why one factor is more important than another and encourage them to think about what would happen if it were different.
It is a way of reasoning that develops the skills associated with deductive hypothetical reasoning, so fundamental in scientific education, which strives to promote scientific literacy. The authors thank the referees for their important comments, which made the text clearer and more precise.
It is today that the Sun is closer to the Earth than on any other day of the year, which means that today the Earth will receive from the Sun greatest number light and warmth in 2015!
When the Earth is closest to the Sun, it is winter in the northern hemisphere. This remarkable photo of a solar halo was taken on January 2, 2015 in Alaska. © Tracey Mendenhall Porreca
Channel, physics at school 4, 12. Retraining group for teaching physics, reading in physics - mechanics. Allen, Astrophysical Quantities 2nd ed. Macmillan, Astronomy Today. 2nd ed. Lissauer, Planetary Sciences. Lang, astrophysical data: planets and stars.
Best Answer: The phenomenon of astronomical seasons, or various effects heat and light are different in "parts of the Earth's arc every year, caused" by the tilt of the Earth around its axis of rotation. The "tilt" of the Earth's rotation axis determines the change in seasons going to change the angle of incidence sun rays that reach the surface. When the hemisphere is in winter time the sun's rays fall on the surface with a smaller inclination relative to the horizon; as a consequence, there is a lower degree of irradiation “the atmosphere and surface absorb less heat and the entire” hemisphere is cooler.
Strange? Not at all! Let us remember that the seasons change not because the Earth is either closer or further from the Sun, but because the axis of rotation of our planet is inclined to the plane earth's orbit. As a result, the Sun illuminates mostly Northern Hemisphere Earth, and the other half of the year - southern. Therefore, in southern hemisphere It's real summer now!
Conversely, when it is summer in one hemisphere, the rays tend to be perpendicular to the "horizon and as" the atmosphere, so that the surface absorbs more heat, with a consequent increase in temperature. If "the axis of rotation was perfectly perpendicular to the plane of the orbit there would be no astronomical seasons, that is" the effects of heat and light in a given part of the planet would be constant throughout the year.
Note that since the Earth's orbit is an Ellipse, there is indeed a period of the year when the Earth is closest to the Sun. Currently, the Earth reaches perihelion in early January, while the further orbit is reached in early July. This situation may change over the next millennium due to the slow precession of the Earth's orbit, which completes a full cycle of 000 years. Reaching aphelion or perihelion does not affect the temperature of the Earth, if not a small part, as the “orbit is described by the Earth” is a very small eccentric ellipse, then the variation in the distance from the Sun between aphelion and perihelion is very small.
However, as we wrote last year, six months is a rough estimate. Let's take a closer look.
The boundaries of the astronomical seasons are the moments of the equinoxes and solstices. (These are not random dates, but singular points in the Earth’s orbit, marking the key “stages” of the process of illumination of the Earth by the Sun/) For example, astronomical summer lasts from the moment summer solstice, which in different years occurs on June 20, 21 or 22, until the autumnal equinox occurs on September 22 or 23. Thus, the duration of summer is 93.6 days. Autumn lasts from the autumn equinox until the winter solstice, which occurs on December 21 or 22. Let's count the number of days on the calendar between these dates and make sure that autumn is 4 days shorter! - its duration is 89.8 days! Winter is even shorter - only 89 days. Finally, the duration of spring is 92.8 days. Here visual proof the fact that the Earth moves in an ellipse and is closer to the Sun in winter than in summer!
The famous photograph of the Earth, the so-called. "Blue Marble" by Eugene "Chernan" during the Apollo 17 mission. It all must be precession earth's axis, which oscillates like a slow toy kick, turning its wheels almost every 26,000 years. Spring, my favorite time years, getting shorter and shorter.
This is because the axis around which the Earth rotates is what is called precession. Under the influence of others celestial bodies- mainly the Sun and Moon, - but also other planets - it oscillates like the slow motion of a toy, turning its wheels for almost 26,000 years. That's why North Star, the most bright star the nearest pole of the northern sky, changes us from time to time.
However, the difference in distances to the Sun in summer and winter is small - only about 5 million km. Today it is equal to 147 million 096 thousand 204 kilometers. At aphelion it will exceed 152 million kilometers. The distance varies by approximately 3%. The size of the Sun in our sky changes just as much - completely invisible to the naked eye!
Although precession affects many globes in the solar system, our galaxy and the entire universe, we are most interested in its effect on Earth. At this hour the Earth will return to the Sun with its north pole, A South Pole will turn towards our star behind. This summer will last 93.5 days.
Summer is the longest season of the year in the northern hemisphere. And that's because the moment after that, the Earth is farthest from the Sun, so our planet is moving through its slowest year. And besides - by precession - our summer continues to grow, feeding on the spring.
We all know very well that in different times The Sun behaves differently every year. In summer it rises early, goes high in the sky and sets late. In winter, on the contrary, the Sun appears above the horizon late and, having made a low and shortcut across the sky, sets early. In summer the days are long and the nights are short; In winter the days are short and the nights are long. In spring and autumn, day and night differ little in duration. How can all this be explained? After all, we know that the change of day and night, that is, the rising and setting of the Sun, occurs because the Earth rotates around its axis. Why doesn’t it spin the same way all year round? Or maybe the length of day and night depends on some other reason?
In turn, when we are in summer and we like autumn colors - this year from September 22 to December 21 - they have spring. This will happen until the continent changes. Of course, only in theory, from the Gregorian Reformation until almost fifty thousand years ago, we make a calendar to avoid this - this July was still in the summer month and that winter of February.
However, we should not complain about the Earth's axis. If it did not oscillate like a bowl and straighten like a pine tree, constantly yielding in the plane determined by the movement of our globe around the Sun, we wouldn't be in the middle of the year at all! By the way, it is worth remembering that astronomical seasons are not the same as weather.
To find out, let’s take a closer look at how the Sun behaves at different times of the year and what connection there is between the behavior of the Sun and weather changes.
In both summer and winter, the Sun rises in the eastern part of the horizon, sets in the western part, and at noon is in the south highest above the horizon. But in summer the Sun rises between the east and the north, that is, in the northeast, and sets between the west and the north, that is, in the northwest. Due to this, its visible path across the sky is long, and a lot of time must pass before the Sun can reach the south; During this time the Sun will have time to rise high. In winter, the Sun rises between east and south, that is, in the southeast, and sets between west and south, that is, in the southwest. Its path across the sky is shorter than in summer. The Sun reaches the south in a relatively short time and does not have time to rise to a significant height (Fig. 5).
In Poland it is considered summer when the average daily temperature exceeds 15 degrees Celsius. When it falls again between 15 and 5 degrees, it will begin to fall. For simplicity, Polish meteorologists assigned each of the four main five seasons to three months. Yes, summer lasts from June to August, autumn from September to November, winter from December to February and spring from March to May.
For example, in our region, global spring now begins almost two weeks earlier than three decades ago. Winter is getting shorter. Apparently, at the Institute of Meteorology and Management water resources in Warsaw they are seriously wondering whether they will give up the December autumn and the only months of winter in Poland in order to recognize January and February. Or maybe this will happen at the end and in February?
Rice. 5. Visible path Sun above the horizon at different times of the year
Let's take Moscow, for example. In summer in Moscow, at the end of June, the Sun is above the horizon for approximately 17 and a half hours, and in winter, at the end of December, only 6 and a half. At noon, when the Sun is in the south, in summer it is more than 5 times higher above the horizon than in winter.
However, it is possible that humanity will find all these new items. Current global change climate can have such a dramatic effect that they swarm from the Earth's surface to some of the species that live there. Moreover, the precession of the Earth's axis affects the climate of our planet. Together with changes in the eccentricity of the earth's orbit and changes in the inclination of the planet's axis to the ecliptic plane, precession makes it in the atmosphere, decreasing or increasing the brightness in polar regions and causing the Earth to undergo glaciations or interglaciations.
It's easy to go through all this precession. Vacation ten or more times in the same hotel. Not at all if we're talking about about Turkey - a country that rents from 30% to 40% every year. travelers from Lithuania, and these numbers are constantly growing. Holidays Bodrum, Antalya, Marmaris, Kemer, and another on the Mediterranean and Aegean seas, located at the height of the city, attracts Lithuanian crowds every year, and many of them return to this country and to as soon as possible. So what is the secret of Turkey's stagnant popularity?
It is not difficult to understand that it is precisely due to this difference in the behavior of the Sun in winter and summer that it is cold in winter and warm in summer. After all, in summer the Sun illuminates the surface of the Earth much longer than in winter. And the sun's rays not only give light to the Earth, but also warm it.
But also higher value has a difference in the height of the Sun's path above the horizon. When the Sun is low in the sky, its rays have to pass through a thick layer of air envelope, which not only weakens the light of the Sun, but also delays the heat of its rays. In addition, in this case the sun's rays fall on the earth's surface not directly, but obliquely, as if sliding along it. As a result of all this, when the sun is low, the sun's rays warm the soil very little.
The country you want to return to. Moreover, some travelers fly to this country two or three times a year - in spring, summer and autumn. Often if found correct option, travelers will use the same hotel until the end of the year for many years in a row. For example, such hotels have already become Dolphin chains, as well as Amara, Gural and others located near Kemer, “I called me.”
According to the travel agent, the reasons why Türkiye is so loved by holidaymakers are definitely not the only ones. Good, like Western Europe, only cheaper. To begin with, Türkiye offers holidaymakers particularly excellent value for money to the expectations of our travellers. This destination is famous for its excellent Western service high level, but prices are much lower than in Western Europe. Of course, we have all heard of oriental hospitality, but holidaymakers in Turkey do not feel it. No matter where you are - in a hotel, in a cafe or in a restaurant pleasant communication and goodwill await you everywhere.
It’s completely different when the Sun is high above the horizon. Then the sun's rays pass through a relatively thin layer air and fall to the earth's surface almost vertically. Thanks to this, they greatly warm the soil.
Rice. 6. Path of sunlight at low and high high positions Sun
Look at fig. 6. The left side of the picture shows how a beam of sunlight falls on the Earth when the Sun is low in the sky. The right side of the picture shows a beam of rays from the Sun falling on the Earth when it is high in the sky. The same beam of rays in the first case (when the Sun is low) illuminates significantly large area on earth's surface and a thicker layer of air passes through than in the second case. This makes it clear why winter sun It barely warms, but the summer one, on the contrary, warms very much.
Thus, we see that winter cold is explained by the fact that in winter the Sun is not above the horizon for long and its rays almost do not warm the surface of the Earth. In summer, on the contrary, the Sun stays above the horizon for a long time, and its rays greatly warm the Earth. That's why it gets warm in the summer.
