Everyone has long known how inquisitive children are. They sometimes ask questions that make adults blush. It seems that everything is elementary and simple, however, it is difficult for many parents to give an answer at the same moment. In order not to get into such difficult and awkward situations when talking with a child, you need to prepare for them thoroughly.
Therefore, we will analyze those questions that are most often heard from the lips of children and that are of interest to adults.
The phrase with a question about the shade of the skies puts many parents in a rather awkward position. Children are interested in why the sky is light blue, not yellow, not red, because the cosmos is black? But if we, adults, find it difficult to answer, then this means that we ourselves do not really know the answer to this question, and it never occurred to us to ask it. And many, not knowing the correct answer, translate the topic.
Light, which consists of 7 shades of the spectrum, usually passes through the atmosphere. There is a collision of solar photons with many gas molecules contained in the air. This leads to such a phenomenon as scattering. The most interesting is the moment concerning the number of particles that are engaged in the emission of a short wave of blue hue. There are 8 times more of them. It turns out that on the way to the Earth, the shade of the sun's rays changes from white to light blue. How to explain all this to a child? But the child is still very small, what to talk to him about the photons of the sun's rays that collide with gas molecules.
Short answer in conversation for kids
The air that surrounds us is composed of tiny and constantly moving particles - gases, dust particles, motes, water vapor. They are so small that they can only be seen under a microscope, and sunlight is a harmony of seven shades. A beam that passes through air has to collide with small particles. And this leads to the fact that the shades in it are separated. And since there is more light blue in the color spectrum, we only see it. Or you can simply answer briefly that the sun's rays color the air in a light blue hue.
Joking (original) answer
Everyone thinks that air is transparent, but it is a light blue hue. We are very, very far from the sun. Looking up, we can only see a thick layer of air. It is so pure that it appears light blue. It is also possible and jokingly to answer that it is light blue, because in the game, whoever is faster always wins the light blue hue.
Funny answer for adults
Why the sky is blue? - This is all my own, the blues always have this!
Video presentation for children
Why is the sea blue, the grass green, and the sunset red?
Sea
The shade of the water of the sea depends on how deep the penetration of the rays. The sea has a good ability to absorb and scatter any rays. But the yellow tint of the beam is absorbed much faster, even not at depth. And the absorption of the blue tint of the beam is very slow, even at great depths. Therefore, it seems to us that the water in the sea is blue. The shade of the sea can be transparent, and blue, and green.
Grass
A green leaf absorbs carbon dioxide into the cells, and releases oxygen into the air. He desperately needs this. But what does it have to do with it? The sun is the main source of life. The sun's rays fall on the leaves. Their cells contain a green substance called chlorophyll. Leaves and grass, thanks to the content of chlorophyll in them, which is involved in the development of the most important nutrients, live perfectly.
The substances produced by chlorophyll are well known to us in the form of sugar, starch and protein. They are found both in the cells of plants, animals, and in the cells of the human body. And the production of these nutrients comes from carbon dioxide. The green leaf is an amazing factory. If the sun's rays touched the leaf, then we can say about their wonderful life. If there is no sunlight, then there is no factory, respectively.
Sunset
You have probably often wondered about the color of the sky at sunset. Perhaps many people wonder why the skies at sunset are sometimes scarlet, and sometimes red. What is it connected with?
This is because red is the longest wavelength of light. He can break through a thick layer of air. But why does it look light blue only in clear weather?
And this is also explained quite simply. When the weather is overcast, most of the sun's rays simply do not reach the surface of the earth. And what can still break through begins to refract drops of water suspended in the air. There is a distortion of the light wave. If the color of the sky is gray, then this is the same process, but with larger clouds. So we sorted out the question regarding the blueness of the skies and the redness of the sunset. These issues can be studied in more detail by getting acquainted with the objective laws of physics.
Why is the sky blue in terms of science: physics, chemistry?
Our planet is surrounded by air, which forms the atmosphere. The atmospheric air contains a large amount of oxygen, carbon dioxide, nitrogen, water vapor, microscopic dust particles that are constantly moving.
Sunlight manages to penetrate the atmospheric layers of air. The gases that are contained in the air work in the decomposition of white light into 7 components, spectra. These are all the colors of the rainbow and that's why it seems to us that the sky is light blue. The moon has no atmosphere and appears to be black. Astronauts entering orbit on spaceships manage to see a beautiful black velvet sky with sparkling stars and planets.
Wikipedia about the blue color of the sky
Wikipedia informs that the sky only looks light blue. In reality, the sky scatters all other colors of the rays, in addition to light blue, blue and violet. All of them together appear light blue to us.
Why is it light blue?
Sunlight has 7 colors in its spectrum, which are combined together - red, orange, yellow, light blue, indigo and violet. You can look at the pictures, remember the rainbow. Each ray needs to pass through a thick air layer. And at this moment the shades are splashed. At the same time, light blue is visible to us more than others, since it is very resistant.
What does the Bible say: why is the sky blue?
The sky is light blue, because the Almighty was pleased to create it that way.
The expression about the blue sky in English translation
Out of a clear blue sky - clear blue sky.
Scientists find blue skies on Pluto and traces of lakes on Mars
Scientists have discovered organic particles in Pluto's atmosphere called tholins. They themselves are gray or red. When they reflect sunlight, the atmosphere of this planet appears light blue. In addition, several small areas were found here that are covered with ice.
Another discovery has a connection with the planet Mars. Scientists prove that in the distant past for many years, the surface of this planet was covered with lakes. Shortly before this, there were several indications of the existence of salt water on Mars. It is the flow of salt water, as many scientists believe, that are responsible for the fact that the surface of the planet has dark stripes. They appear at the moment when the temperature on this planet rises above - 23 degrees. They disappear when it gets cold.
When the wind throws a white fluffy transparent cape over the beautiful blue sky, people begin to look up more and more often. If at the same time it also puts on a large gray fur coat with silver threads of rain, then those around hide from it under umbrellas. If the outfit is dark purple, then everyone is sitting at home and wanting to see the sunny blue sky.
And only when such a long-awaited sunny blue sky appears, which puts on a dazzling blue dress decorated with golden sunbeams, people rejoice - and smiling, leave their homes in anticipation of good weather.
The question of why the sky is blue has puzzled people's minds since time immemorial. Greek legends have found their answer. They claimed that this shade is given to it by the purest rock crystal.
At the time of Leonardo da Vinci and Goethe, they were also looking for an answer to the question why the sky is blue. They believed that the blue color of the sky is obtained by mixing light with darkness. But later this theory was refuted as untenable, since it turned out that by combining these colors, you can get only the tones of the gray spectrum, but not the color one.
After some time, the answer to the question of why the sky is blue was tried to be explained in the 18th century by Mariotte, Bouguer and Euler. They believed that this was the natural color of the particles that make up the air. This theory was popular even at the beginning of the next century, especially when it was found that liquid oxygen is blue, and liquid ozone is blue.
The first more or less sensible idea was given by Saussure, who suggested that if the air were completely clean, without impurities, the sky would turn out to be black. But since the atmosphere contains various elements (for example, steam or water drops), they, by reflecting color, give the sky the desired shade.
After that, scientists began to get closer and closer to the truth. Arago discovered polarization, one of the characteristics of scattered light that bounces off the sky. In this discovery, the scientist was definitely helped by physics. Later, other researchers began to look for the answer. At the same time, the question of why the sky is blue was so interesting for scientists that a huge number of different experiments were carried out to find it out, which led to the idea that the main reason for the appearance of the blue color is that the rays of our Sun simply scatter in the atmosphere.
Explanation
Rayleigh, a British researcher, was the first to create a mathematically sound answer to molecular light scattering. He suggested that light is scattered not because of the impurities that the atmosphere possesses, but because of the air molecules themselves. His theory was developed - and here are the conclusions scientists came to.
The sun's rays make their way to the Earth through its atmosphere (a thick layer of air), the so-called air shell of the planet. The dark sky is completely filled with air, which, despite being completely transparent, is not a void, but consists of gas molecules - nitrogen (78%) and oxygen (21%), as well as water droplets, steam, ice crystals and small pieces of solid material (for example, particles of dust, soot, ash, ocean salt, etc.).
Some rays manage to freely pass between gas molecules, completely bypassing them, and therefore reach the surface of our planet without changes, but most of the rays collide with gas molecules that come into an excited state, receive energy and release multi-colored rays in different directions, completely coloring the sky, resulting in a sunny blue sky.
White light itself consists of all the colors of the rainbow, which can often be seen when it is broken down into its component parts. It so happens that blue and violet colors scatter the most because they are the shortest part of the spectrum, since they have the shortest wavelength.
When mixed in an atmosphere of blue and purple with a small amount of red, yellow and green, the sky begins to "glow" blue.
Since the atmosphere of our planet is not homogeneous, but quite different (it is denser near the Earth's surface than at the top), it has a different structure and properties, we can observe blue overflows. Before sunset or sunrise, when the length of the sun's rays increases significantly, blue and purple colors are scattered in the atmosphere and absolutely do not reach the surface of our planet. The yellow-red waves successfully reach, which we observe in the sky during this period of time.
At night, when the sun's rays, falling on a certain side of the planet, have no opportunity, the atmosphere there becomes transparent, and we see the "black" space. This is how astronauts above the atmosphere see it. It is worth noting that the astronauts were lucky, because when they are over 15 km above the earth's surface, during the day they can simultaneously observe the Sun and stars.
Sky color on other planets
Since the color of the sky is largely dependent on the atmosphere, it is not surprising that on different planets it is of different colors. Interestingly, the atmosphere of Saturn is the same color as on our planet.
Very beautiful aquamarine skies of Uranus. Its atmosphere consists mainly of helium and hydrogen. It also contains methane, which completely absorbs red and scatters green and blue. The blue skies of Neptune: in the atmosphere of this planet there is not as much helium and hydrogen as ours, but there is a lot of methane, which neutralizes the red light.
The atmosphere on the Moon, a satellite of the Earth, as well as on Mercury and Pluto, is completely absent, therefore, light rays are not reflected, so the sky is black here, and the stars are easily distinguishable. The blue and green colors of the sun's rays are completely absorbed by the atmosphere of Venus, and when the Sun is near the horizon, the skies here are yellow.
In short, then ... "Sunlight, interacting with air molecules, scatters into different colors. Of all the colors, blue is the best for scattering. It turns out that he actually captures the airspace.
Now let's take a closer look
Only children can ask such simple questions that a fully grown person does not know how to answer. The most common question tormenting children's heads is: "Why is the sky blue?" However, not every parent knows the right answer even for himself. The science of physics and scientists who have been trying to answer it for more than one hundred years will help find it.
False Explanations
People have been searching for the answer to this question for centuries. People of antiquity believed that this color is a favorite for Zeus and Jupiter. At one time, explanations of the color of the sky excited such great minds as Leonardo da Vinci and Newton. Leonardo da Vinci believed that when combined, darkness and light form a lighter shade - blue. Newton associated the blue color with the accumulation of a large number of water droplets in the sky. However, it was not until the 19th century that a correct conclusion was reached.
Range
In order for a child to understand the correct explanation with the help of the science of physics, he first needs to understand that a beam of light is particles flying at high speed - segments of an electromagnetic wave. In a stream of light, long and short rays move together, and are perceived by the human eye together as white light. Penetrating in the atmosphere through the smallest drops of water and dust, they scatter into all colors of the spectrum (rainbow).
John William Rayleigh
Back in 1871, the British physicist Lord Rayleigh noticed the dependence of the intensity of scattered light on the wavelength. Scattering of the Sun's light by irregularities in the atmosphere explains why the sky is blue. According to Rayleigh's law, blue sun rays scatter much more intensely than orange and red ones, since they have a shorter wavelength.
The air near the surface of the Earth and high in the sky is made up of molecules, causing sunlight to scatter high in the air. It reaches the observer from all sides, even from the most remote ones. The spectrum of scattered air light differs markedly from direct sunlight. The energy of the first has been moved to the yellow-green part, and the second to the blue.
The more direct sunlight is scattered, the colder the color will appear. The strongest scattering, i.e. The shortest wavelength is for violet, the longest wavelength is for red. Therefore, during sunset, the distant parts of the sky appear blue, and the closest ones appear pink or scarlet.
Sunrises and sunsets
During sunset and dawn, a person most often sees pink and orange shades in the sky. This is because light from the sun travels very low to the surface of the earth. Because of this, the path that light needs to travel during sunset and dawn is much longer than during the day. Due to the fact that the rays travel the longest path through the atmosphere, most of the blue light is scattered, so the light from the sun and nearby clouds appear reddish or with a pink tint to a person.
The world around us is full of amazing wonders, but we often do not pay attention to them. Admiring the clear blue of the spring sky or the bright colors of the sunset, we do not even think about why the sky changes color with the change of time of day.
We are accustomed to bright blue on a fine sunny day and to the fact that in autumn the sky becomes hazy gray, losing its bright colors. But if you ask a modern person about why this happens, then the vast majority of us, once armed with school knowledge of physics, are unlikely to be able to answer this simple question. Meanwhile, there is nothing complicated in the explanation.
What is color?
From a school course in physics, we should know that differences in the color perception of objects depend on the wavelength of light. Our eye can only distinguish a fairly narrow range of wave radiation, with blue being the shortest and red being the longest. Between these two primary colors lies our entire palette of color perception, expressed by wave radiation in different ranges.
A white sunbeam actually consists of waves of all color ranges, which is easy to verify by passing it through a glass prism - you probably remember this school experience. In order to remember the sequence of changing wavelengths, i.e. the sequence of colors in the spectrum of daylight, invented a funny phrase about a hunter that each of us learned in school: Every Hunter Wants to Know, etc. 
Since red light waves are the longest, they are the least susceptible to scattering during transmission. Therefore, when you need to visually highlight an object, they use mainly red color, which is clearly visible from afar in any weather.
Therefore, a stop signal or any other warning light is red, not green or blue.
Why does the sky turn red at sunset?
In the evening hours before sunset, the sun's rays fall on the surface of the earth at an angle, and not directly. They have to overcome a much thicker layer of the atmosphere than in the daytime, when the surface of the earth is illuminated by the direct rays of the sun.
At this time, the atmosphere acts as a color filter, which scatters the rays of almost the entire visible range, except for the red ones, which are the longest and therefore most resistant to interference. All other light waves are either scattered or absorbed by water vapor and dust particles present in the atmosphere.
The lower the sun drops in relation to the horizon, the thicker the layer of the atmosphere the light rays have to overcome. Therefore, their color is increasingly shifted towards the red part of the spectrum. A folk sign is associated with this phenomenon, saying that a red sunset portends a strong wind the next day. 
The wind originates in the high layers of the atmosphere and at a great distance from the observer. Oblique solar rays highlight the outlined zone of atmospheric radiation, in which there is much more dust and vapor than in a calm atmosphere. Therefore, before a windy day, we see a particularly red, bright sunset.
Why is the sky blue during the day?
Differences in the length of light waves also explain the pure blue of the daytime sky. When the sun's rays fall directly on the surface of the earth, the layer of the atmosphere they overcome has the smallest thickness.
Scattering of light waves occurs when they collide with gas molecules that make up air, and in this situation, the short-wavelength light range is the most stable, i.e. blue and purple light waves. On a fine windless day, the sky acquires amazing depth and blueness. But why do we then see blue and not purple sky?
The fact is that the cells of the human eye, which are responsible for color perception, perceive blue much better than purple. Yet purple is too close to the edge of the perceptual range.
That is why we see the sky as bright blue if there are no scattering components in the atmosphere, except for air molecules. When a sufficiently large amount of dust appears in the atmosphere - for example, in a hot summer in a city - the sky seems to fade, losing its bright blue.
Gray sky of bad weather
Now it is clear why the autumn bad weather and winter slush make the sky hopelessly gray. A large amount of water vapor in the atmosphere leads to the dispersion of all components of the white light beam without exception. Light rays are crushed in the smallest droplets and water molecules, losing their direction and mixing over the entire range of the spectrum. 
Therefore, light rays reach the surface, as if passed through a giant diffuser. We perceive this phenomenon as a grayish-white color of the sky. As soon as moisture is removed from the atmosphere, the sky turns bright blue again.
There are millions of questions that, being children, we do not receive an answer, and when we grow up, we are simply embarrassed to ask. One of these unanswered questions: "why is the sky blue?" And everything would be fine, and without this knowledge you can live, but when a child begins to ask such tricky questions to his parents, they often become ashamed, and they begin to change the subject. Then the child grows up not knowing the answer, he has his own children and everything repeats again. Let's break this "vicious circle" and understand the reasons why the sky is blue. Consider the issue from all possible points of view.
The phenomenon of blue sky in terms of physics
Let's get straight to the point, the sky is blue because the earth's atmosphere scatters the light of the sun. All research conducted over the past 200-300 years comes down to this. Consider a few axioms that affect the blue sky phenomenon:
- The white light of the sun is a combination of different color streams. White color "separately" does not exist. As everyone knows, there are only 7 colors (red, orange, yellow, green, blue, blue, purple), the rest of the colors are obtained only when they are combined. White color is obtained by combining all seven colors. It is worth considering that it is precisely the colors that we can distinguish with the eye that are meant.
- The atmosphere is not empty, it consists of many gases: nitrogen (78%), oxygen (21%), carbon dioxide, water in its various states (steam, ice crystals). There is also a lot of dust around us, elements of various metals. All of them distort the white light of the sun.
- The air that surrounds us and that we breathe is actually opaque. In any case, in large quantities. We do not live in a vacuum, after all.
From these three facts we will proceed further.
Story
Back in the 19th century, a scientist named John Tyndall conducted research that proved that we see the sky blue because of particles in the atmosphere. In his laboratory, he artificially created a fog with dust particles and directed a bright white beam at it - the color of the fog changed to bluish. 30 years later, in 1899, the physicist Rayleigh refuted the research of his predecessor and published evidence that the sky is blue because of air molecules and no dust in it. This phenomenon is called diffuse sky radiation You can read more about this on Wikipedia.
The sky looks blue because air scatters short wavelength light more than long wavelength light. Since blue light has a shorter wavelength, at the end of the visible spectrum, it scatters more in the atmosphere than red. (Source: Wikipedia)
What is light? Light is a stream of photons, some we can see with our eyes and some we can't. So, for example, we see the standard spectrum of colors, but the ultraviolet, which also emits the sun, does not. What color we see in the end depends on the "wavelength" of this stream. This wavelength determines what color you get.
So. We have determined that the sun sends us quanta with a wavelength that corresponds to white, but how does it turn into blue as it passes through the atmosphere? Let's take the example of a rainbow. Rainbow - is a direct example of the refraction of light and its division into a spectrum. You can create your own rainbow using a glass prism at home. The decomposition of color into a spectrum is called dispersion.
So, our sky functions as a prism. Most white light changes its wavelength as it passes through gas molecules in the atmosphere. As a result, photons “leaving” the molecules have a different color. This color can be either purple, red, or blue and blue.
Why do we see blue and not red?
What color we eventually see when light travels from the sun to the earth depends on which photons prevail. For example, when light passes through the atmosphere, the number of blue color quanta is 8 times more than red, and violet is 16 times! This is due to the very different wavelength, so violet and blue scatter strongly, and red and yellow scatter much worse. Based on this theory, the sky should be purple, but it is not. This is due to the fact that purple is much worse perceived by the human eye, unlike blue. That's why the sky is blue.
Video about why the sky is blue:
Why is the sky blue during the day and the sunset is red
Everything, again, is connected with the dispersion of color. The angle of incidence of solar white light becomes smaller, and the light passes through more air molecules, the wavelength of light increases. This amount is enough to diffuse to red.
The answer to the question why the sky is blue for children
If a child asked you a question about the blue sky, you certainly will not tell him about dispersion, spectra and photons. It is enough to quote from the children's book "100 Children's Why" Tatiana Yatsenko:
Usually we draw the sun's rays in yellow. But in fact, the light of the sun is white and consists of seven colors. These are the colors of the rainbow: red, orange, yellow, green, blue, indigo, violet. Not all colors pass through the air, only blue, indigo and violet. They color the sky.
This will be enough. On our website, you can also download a presentation on the topic: “Why the sky is blue” at the link: It may come in handy in the classroom at school.
