The farthest stars in the Milky Way visible to the naked eye. Bukina Irina Yurievna Stars and the sun

Surdin V. Are stars visible from a deep well during the day? //Quantum. - 1994. - No. 1. - P. 11-13.

By special agreement with the editorial board and editors of the journal "Kvant"

Rice. 1. This illustration appeared in the 1899 edition of Sir Robert Ball's 1889 book Star-Land with the caption "How the stars are to be seen in broad daylight."

There is an old and quite widespread belief that during the day you can see stars from a deep well. From time to time this is stated by quite authoritative authors. Thus, more than two thousand years ago, Aristotle wrote that stars could be visible during the day from a deep cave. Somewhat later, Pliny repeated the same thing, replacing the cave with a well. Many writers mentioned this in their works: remember, in Kipling, the stars are visible at noon from the bottom of a deep gorge. And Sir Robert Ball in his book “Star-Land” (Boston, 1889) gives detailed recommendations on how to observe stars during the day from the bottom of a high chimney (Fig. 1), explaining this possibility by the fact that in a dark chimney a person’s vision becomes more spicy.

So, are stars visible during the day? What does the experiment say about this? I confess that until now I have not had the opportunity to go down into a very deep well or climb into a tall pipe. However, at different times there were inquisitive citizens who tried to discover the “well effect” themselves. The famous German naturalist and traveler Alexander Humboldt, trying to see the stars during the day, descended into the deep mines of Siberia and America, but to no avail. There are some restless heads these days too. For example, Komsomolskaya Pravda journalist L. Repin in the issue dated May 24, 1978. wrote: “They say that in broad daylight you can see the stars in the sky if you go down into a deep well. One day I decided to check if this was true, I went down into a sixty-meter well, but I still couldn’t see the stars. Just a small square of dazzling blue sky.”

Another evidence: an experienced amateur astronomer from Springfield (Massachusetts, USA), Richard Sanderson, describes his observations in the Skeptical Inquirer magazine (1992):

“Once about 20 years ago, when I was working as an intern at the planetarium of the Springfield Science Museum, my colleagues and I began to argue about this ancient belief. The director of the museum, Frank Korkosh, heard our dispute and proposed to resolve it experimentally: he took us to the basement of the museum, where a tall and narrow chimney began. There was a small door leading into it, through which we could stick our heads. I remember the feeling of excitement at the prospect of seeing the night luminaries in broad daylight.

Looking up along the chimney, I saw a shining circle against the background of the impenetrable blackness of the stove interior. From the surrounding darkness, the pupils of my eyes dilated and a piece of the sky shone even brighter. I immediately realized that with the help of this “device” I would not be able to see the stars during the day. When we got out of the museum basement, director Korkosh noticed that only one star can be observed during the day in good weather: this is the Sun.”

So, the stars of the night are not visible during the day from a deep well, nor from a high chimney. However, let’s not rush to conclusions: through some pipes the stars are visible even during the day. We are talking about astronomical tubes - telescopes. What's the matter? Why does a tube with lenses allow you to see stars during the day, but a simple tube does not?

First of all, let's think about why the stars are not visible during the day? Yes, simply because the sky is bright from diffused sunlight. If for some reason the scattered light diminishes, such as a total solar eclipse, the bright stars and planets will become perfectly visible during the day. They are also clearly visible in outer space or from the surface of the Moon. Why does the sunlight scattered in the atmosphere hide them from us? After all, the light of the stars does not weaken.

To understand this, you need to imagine the mechanism of our vision. As is known, the eye lens - the pupil - creates an image on the back surface of the eye, covered with a light-sensitive layer - the retina, which consists of a large number of elementary light receivers - cones and rods. They are sensitive to color in different ways, but for us now this is not important, so for simplicity we will call them all cones. The important thing is that each cone transmits information to the brain about the flow of light falling on it, and the brain synthesizes from these individual messages (signals) a whole picture of what it saw.

The eye is a very complex receiver of information, but in some ways it is similar to a smart electronic device such as a radio. The eye also has an automatic gain control system that reduces its sensitivity in bright light and increases its sensitivity in darkness. It also has a noise reduction system that smoothes out random fluctuations in the light flux both in time and across the surface of the retina. This system has certain threshold characteristics, so the eye does not notice rapid changes in the image (cinema principle) and small fluctuations in brightness.

When we observe a star at night, the flux of light from it per cone, although small, is significantly greater than the flux from the dark sky falling on neighboring cones. Therefore, the brain records this as a significant signal. But during the day, so much light from the sky falls on all the cones that a small addition in the form of star light coming to one of these elements is not perceived by the brain as a real difference in the flow of light, but is attributed to fluctuations.”

A star can become visible against the background of the daytime sky only if the flux of light from it is comparable to the flux from the sky area that the pupil projects onto one cone. The angular size of this area is called the resolution of the human eye and is about 1".

Of all the star-shaped objects, only Venus is sometimes visible in the daytime sky. Seeing her is very difficult: the sky must be perfectly clear and you need to at least approximately know where in the sky Venus is currently located. All other planets and stars have a brightness much weaker than that of Venus, so it is completely impossible to see them without a telescope during the day. However, some astronomers claim that under ideal conditions they were able to observe Jupiter during the day, which is several times fainter than Venus. But no one has yet been able to see the brightest star in our sky - Sirius - during the day at sea level. They say it was seen high in the mountains, against a dark purple sky.

It's quite easy to see that a bright background is hiding the bright spots from us. Here is what Yakov Perelman advises on this matter in “Entertaining Astronomy” (M.-L., Gostekhizdat, 1949, p. 155):

“A simple experiment can clearly explain this disappearance of stars in daylight. Several holes are punched in the side wall of the cardboard box, located like some kind of constellation, and a sheet of white paper is glued to the outside. The box is placed in a dark room and illuminated from the inside: holes illuminated from the inside then clearly appear on the broken wall - these are stars in the night sky (Fig. 2). But one has only to light a sufficiently bright lamp in the room, without stopping the illumination from inside, and the artificial stars on the sheet of paper disappear without a trace: it is “daylight” that extinguishes the stars.”

What does a telescope do that allows us to easily observe night stars during the day? Of course, the telescope lens collects much more light than the pupil of the eye. But in this sense, the image of a star and the sky are equivalent - when observed through a telescope, the flow of light from them into the eye increases by the same number of times, approximately equal to the ratio of the area of ​​the lens to the area of ​​the pupil. Another thing is much more important - the telescope improves the resolution of the eye, because it increases the angular size of the observed objects. In this case, the same area of ​​​​the sky is projected onto a larger number of cones, which means that each of them receives proportionally less light. For example, if a telescope magnifies the angular size of objects by A times, then the observed brightness of the sky decreases by A 2 times. However, the star has a very small angular size, and its light still falls on a single cone.

But now the additional starlight may already become “solid” against the background of the reduced brightness of the sky. For example, at 45x telescope magnification, the brightness of the sky is effectively reduced by a factor of 45 2 ≈ 2000, and some of the brightest stars and planets become visible against the sky.

What happens: take a telescope with high magnification and you can view the faintest stars during the day? No, that's not true. The Earth's atmosphere is inhomogeneous, so the image of the star is blurred and has a very definite angular size, although very small. At night, in good weather, high in the mountains it is about 1". And during the day, at sea level - at least 2" - 3". Therefore, if the telescope magnifies more than 30 - 60 times, the angular size of the star for the observer exceeds the resolution the ability of the eye and its image falls on several cones.Therefore, there is no point in increasing the increase more strongly: the brightness of the star’s image will weaken in the same way as the brightness of the sky.

Let's evaluate which stars can be seen during the day through a telescope. In clear weather, the daytime sky has a brightness of approximately - 5 m per square minute of arc, i.e. approximately one cone. The brilliance of Venus is about - 4 m. Therefore, we will assume that a star becomes visible if its brightness is no more than 1 m less than the surface brightness of the sky per square minute. As we found out, using a telescope, we can reduce the brightness of the sky by no more than 2000 times, i.e. approximately 8 m. This means that the brightness of the sky will decrease to (-5 m + 8 m) = 3 m per square minute and stars with a brightness of up to 4 m will become visible. The experience of astronomical observations shows that this is so.

We've dealt with the telescope, now let's go back to the well. Can a well reduce the brightness of the sky for an observer in it? In principle, it can, but not with the help of lenses, but purely geometrically, blocking the entire field of view with the exception of a small area, the flux of light from which will be comparable to the flux from a star. But for this, the hole must be visible to an observer sitting at the bottom of the well at an angle of less than 1". With a well diameter of 1 m, its depth must be more than 1 m / sin 1" = 3.4 km! But even so, the observer will only see a point of light, the brightness of which will increase momentarily if any star passes exactly through the zenith. Even if one wishes, it is difficult to consider this procedure as “observation of the starry sky.” And we still need to look for such a well! As for the probability of a bright star passing exactly through the zenith (± 0.5"), then, having left it to the reader to check this with calculations, I can say that we would have to wait for more than one millennium for this sacred second!

Generally speaking, a tall tube can also play a role in daytime star observations. After all, it creates an air channel for us, in which there is practically no scattered sunlight. If this pipe passes through the entire thickness of the atmosphere, then through it we will see the night sky at any time of the day! Almost the entire mass of air is contained in a surface layer about 20 km thick. However, the pipe must be long!

Thus, the belief about daytime observation of stars from a well turned out to be a myth. However, where did he come from? One can only guess about this. Perhaps, while at the bottom of a well or mine, someone actually noticed Venus passing across the sky. But this is very unlikely and, in principle, possible only in tropical countries, where Venus is visible at its zenith. It is more plausible that, having descended into a well or a deep cave, people noticed specks of dust illuminated by the sun against the background of dark walls. Perhaps they were mistaken for stars?

And yet the investigation of this myth cannot be considered complete. It is necessary to take a closer look at the illusions of human vision, at unexpected combinations of natural conditions, at rare physical effects. You, dear readers, can also provide considerable assistance in this regard.

For example, astronomy enthusiast Ramiro Cruz from Houston (Texas, USA) decided to check the rumors that Sirius can be seen in the daytime sky. He was looking for a star in the southwestern sky in April 1992, shortly before sunset. Note that he knew where to look! With the naked eye, he was able to notice Sirius no earlier than 21 minutes before sunset. And armed with 7 × 50 field binoculars, he discovered the star 43 minutes before sunset (Sky and Telescope, vol. 85, N 2, Feb. 1993, p. 112). This data is enough for us to estimate the brightness of the sky at the moment the star is discovered.

Houston is located at 30th north latitude, which means that the celestial equator intersects the horizon there at an angle of 90° - 30° = 60°. Since the observations were made immediately after the spring equinox, the sun was near the equator and also set below the horizon at an angle of 60°. In a minute, the sun passes an arc of 360°/(24·60) = 0.25° across the sky. This means that the height of the sun above the horizon ( A) behind t minutes before sunset

\(~a = 0.25^(\circ) \cdot \sin 60^(\circ)t \approx 0.2t.\)

Therefore, the naked eye sees Sirius at a sun altitude of no more a n ≈ 0.2° 21 ≈ 4.5°, and using binoculars at a b ≈ 0.2° 43 ≈ 9°. In this case, the brightness of the sky at the zenith is, respectively, 7% and 13% of its brightness at noon (D.Ya. Martynov, “Course of Practical Astrophysics”, M.: Nauka, 1977, p. 300). Let us remember that the brilliance of Sirius is just 15 times less than the brilliance of Venus. It is at that moment when the brightness of the sky before sunset decreases by 15 times that Sirius becomes visible to the eye. Binoculars help you see a star in a brighter sky because it enhances the brightness of the star, slightly changing the surface brightness of the sky. Here's a useful experiment done by an astronomy enthusiast from Houston.

Now you can really believe that during the day in the highlands or from an airplane you can see Sirius: after all, at an altitude of 5 - 7 km, the sky during the day is 15 - 20 times darker than at sea level. When you fly on an airplane, pay attention to the sky: are Sirius, Jupiter or Venus visible?

And remember! Observing stars through a telescope during the day is very, very dangerous! After all, you can inadvertently turn the telescope towards the Sun, and then you can go blind.

Author Surdin Vladimir Georgievich

Are stars visible during the day?

There is an old and quite widespread belief that during the day you can see stars from a deep well. From time to time this is stated by quite authoritative authors. More than two thousand years ago, the ancient Greek philosopher Aristotle wrote that stars could be visible during the day from a deep cave. Later, the Roman scientist Pliny repeated the same thing, replacing the cave with a well. Many writers mentioned this in their works: remember, in Kipling - “the stars are visible at noon from the bottom of a deep gorge.” And Robert Ball, in his book “Star-Land” (Boston, 1889), gives detailed recommendations on how to observe the stars during the day from the bottom of a high chimney, explaining this possibility by the fact that in a dark chimney a person’s vision becomes sharper. So, are stars visible during the day? I confess that until now I have not had the opportunity to go down into a very deep well or climb into a tall pipe.

However, at different times there were curious people who tried to discover the “well effect”. The famous German naturalist and traveler Alexander Humboldt, trying to see the stars during the day, descended into the deep mines of Siberia and America, but to no avail. There are some restless heads these days too.

For example, journalist of the Komsomolskaya Pravda newspaper Leonid Repin wrote in the issue dated May 24, 1978: “They say that even in broad daylight you can see stars in the sky if you go down into a deep well. One day I decided to check if this was true, I went down into "a sixty-meter well, but I couldn't see the stars. Only a small square of dazzling blue sky." Here's another piece of evidence. An experienced amateur astronomer from Springfield (Massachusetts, USA), Richard Sanderson describes his observations in the Skeptical Inquirer magazine (1992, volume 17, page 74): “One day twenty years ago, when I was working as an intern in the planetarium of the Springfield Museum science, my colleagues and I began to argue about this ancient belief.

The director of the museum, Frank Korkosh, heard our dispute and proposed to resolve it experimentally. He took us to the basement of the museum, where a tall and narrow chimney began. It had a small door through which we could stick our heads. I remember the feeling of excitement at the prospect of seeing the night luminaries in broad daylight. Looking up along the chimney, I saw a shining circle of blue sky against the background of the impenetrable blackness of the stove interior. From the surrounding darkness, the pupils of my eyes dilated, and a piece of the sky sparkled even brighter. I immediately realized that with the help of this “device” I would not be able to see the stars during the day. When we got out of the museum basement, Director Korkosh noticed that only one star can be observed during the day in good weather: this is the Sun. So, witnesses claim that stars are not visible during the day from a deep well, as well as from a high chimney. However, Let’s not rush to conclusions: through some pipes you can still see stars during the day.

In this case we are talking about astronomical tubes - telescopes. What's the matter? Why does a “tube with lenses” allow you to see stars during the day, but a simple tube does not?

First of all, let's think about why the stars are not visible during the day? The answer is quite obvious: simply because the daytime sky is bright due to sunlight scattered by the atmosphere. If for some reason this background weakens, for example, a total solar eclipse occurs, then the bright stars and planets will be perfectly visible during the day. They are also clearly visible in open space or from the surface of the Moon, where the sky is completely black and there is no background light. Why does the sunlight scattered in the earth's atmosphere hide the stars from us? After all, their own light does not weaken. To understand this, you need to imagine the mechanism of our vision. As you know, the main lens, the pupil, creates an image on the back wall of the eye surface, covered with a light-sensitive layer - the retina, which consists of a large number of elementary light receivers - cones and rods. They are sensitive to light in different ways, but this is not important for us now, and therefore, for simplicity, we will call them all cones. The important thing is that each cone transmits information to the brain about the flow of light incident on it, and the brain synthesizes from these individual messages (signals) a whole picture of what it saw. The eye is a very complex receiver of information, and in some ways it is similar to a smart electronic device, such as a radio. It has an automatic gain control system that reduces eye sensitivity in bright light and increases it in darkness. It also has a noise reduction system that smoothes out random fluctuations in the light flux, both in time and across the surface of the retina. This system has certain threshold characteristics, so the eye does not notice rapid changes in the image (cinema principle) and small fluctuations in brightness. When we observe a star at night, the flux of light from it per cone, although small, is significantly greater than the flux from the dark sky falling on neighboring cones. Therefore, the brain records this as a significant signal. But during the day, so much light from the sky falls on the cones that a small addition in the form of starlight per one of these elements is not felt and is “written off” as fluctuations. It is quite easy to see that it is the bright background of the sky that hides the stars from us. Here is an experiment on this subject that Yakov Perelman advises to conduct in his “Entertaining Astronomy” (Gostekhizdat, 1949, p. 155): “A simple experiment can clearly clarify the disappearance of stars in the daytime sky. To carry it out in the side wall of a cardboard box punch several holes located like some kind of constellation, and stick a sheet of white paper on the outside. The box is placed in a dark room and illuminated from the inside: holes illuminated from the inside then clearly appear on the broken wall - these are stars in the night sky. But all you have to do is, without stopping the illumination from within, light a sufficiently bright lamp in the room - and the artificial stars on the piece of paper disappear without a trace: it is “daylight” that extinguishes the stars." A star can become visible against the background of the daytime sky only if the flow of light from it will be comparable to the flux from the sky area, which the pupil projects onto one cone.Note that the angular size of this area is called the resolution of the human eye and is about 1 arc minute.

Of all the star-shaped objects, only Venus is sometimes visible in the daytime sky. Seeing it is not easy: the sky must be perfectly clear, and you need to know approximately where in the sky it is currently located. All other planets and stars have a brightness much weaker than that of Venus, so it is completely impossible to find them without a telescope during the day. However, some astronomers claim that under ideal conditions they were able to observe Jupiter during the day, which is several times fainter than Venus. But no one has yet been able to observe the brightest star in our sky, Sirius, during the day from sea level. True, they say that she was seen high in the mountains, against the backdrop of a dark purple sky. What does a telescope do that allows us to easily observe night stars during the day? Obviously, the telescope lens collects much more light than the pupil of the eye. But in this sense, the images of the star and the sky are equivalent - when observed through a telescope, the flow of light from them into the eye increases by the same number of times, approximately equal to the ratio of the area of ​​the lens to the area of ​​the pupil. In this case, something else is much more important - the telescope improves the resolution of the eye: after all, it increases the angular size of the observed objects. Moreover, the area that is projected onto one cone during observations with the naked eye is projected into several cones at once in a telescope, which means that each of them receives proportionally less light (for example, if a telescope increases the angular diameter of objects by A times, then the observed brightness of the sky decreases by A 2 times). However, the star has a very small angular size, and its light still falls on a single cone. Thus, the light of the star already appears “solid” against the background of the reduced brightness of the sky. And she becomes noticeable. What happens: take a telescope with high magnification and you can view the faintest stars during the day? No, that's not true. The Earth's atmosphere is inhomogeneous, so the image of the star is blurred and has a very definite angular size, although very small. At night, in good weather, high in the mountains it is about 1 arc. sec. And during the day at sea level - at least 2–3 arc. sec. Therefore, the maximum magnification we can use will be determined so that the star is still a point source. It is approximately 30–60 times. There is no point in a stronger magnification: the image of the star will be projected onto several cones at once, and will begin to weaken in the same way as the brightness of the sky. Let's evaluate how faint stars become visible during the day using a telescope. In clear weather, the daytime sky has a brightness of approximately –5 m per square minute of arc, that is, approximately one cone. The magnitude of Venus is about –4 m. Therefore, we will assume that a star becomes visible if its brightness is no more than one magnitude less than the surface brightness of the sky per square minute. Using a telescope with a magnification of, say, 45 times, we will achieve a decrease in the brightness of the sky background compared to the brightness of the star by 452 (about 2000 times), that is, by about 8 m. This means that in the field of view of the telescope, the brightness of the sky will decrease to +3 m per square minute, and thus stars up to +4 m will become available to us. The experience of astronomical observations shows that this is indeed the case. We've dealt with the telescope, now let's go back to the well. Can a well reduce the brightness of the sky for an observer inside it so that the stars can be seen from it? In principle, purely geometrically, perhaps, blocking the entire field of view with the exception of a small area, the flux of light from which will be comparable to the flux of light from a star. But for this to happen, the hole must be visible at an angle of less than one minute to an observer sitting at the bottom of the well. With a well diameter of 1 m, its depth should be more than 1/sin1´=3.4 km! In this case, the hole of the well will be visible to the observer only as a bright point, the brightness of which will increase only for an instant if any star passes exactly through the zenith. Even if one wishes, it is difficult to consider this procedure as “observation of the starry sky.” ...

There is an old and quite widespread belief that during the day you can see stars from a deep well. From time to time this is stated by quite authoritative authors. More than two thousand years ago, the ancient Greek philosopher Aristotle wrote that stars could be visible during the day from a deep cave. Later, the Roman scientist Pliny repeated the same thing, replacing the cave with a well.

Many writers mentioned this in their works: remember, in Kipling’s words, “the stars are visible at noon from the bottom of a deep gorge.” And Robert Ball, in his book “Star-Land” (Boston, 1889), gives detailed recommendations on how to observe the stars during the day from the bottom of a high chimney, explaining this by the fact that vision is sharper in a dark chimney.

So, are stars visible during the day? The famous German naturalist and traveler Alexander Humboldt, trying to see the stars during the day, descended into the deep mines of Siberia and America, but to no avail. There are some restless heads these days too. For example, journalist of the Komsomolskaya Pravda newspaper Leonid Repin wrote in the issue dated May 24, 1978:

“They say that even in broad daylight you can see the stars in the sky if you go down into a deep well. One day I decided to check if this was true, I went down into a sixty-meter well, but I still couldn’t see the stars. Just a small square of dazzling blue sky".

Here's another piece of evidence. An experienced amateur astronomer from Springfield (Massachusetts, USA), Richard Sanderson describes his observations in the Skeptical Inquirer magazine:

“Once about twenty years ago, when I was working as an intern at the planetarium of the Springfield Science Museum, my colleagues and I began to argue about this ancient belief. The director of the museum, Frank Korkosh, heard our dispute and proposed to resolve it experimentally. He took us to the basement of the museum, where a tall and narrow chimney began. It had a small door through which we could stick our heads. I remember the feeling of excitement at the prospect of seeing the night luminaries in broad daylight.

Looking up along the chimney, I saw a shining circle of blue sky against the background of the impenetrable blackness of the stove interior. From the surrounding darkness, my pupils dilated, and a piece of sky sparkled even brighter. I immediately realized that with the help of this “device” I would not be able to see the stars during the day.

When we got out of the museum basement, director Korkosh noticed that only one star can be observed during the day in good weather: this is the Sun.".

So, witnesses claim that the stars are not visible during the day from a deep well, as well as from a high chimney. However, let’s not rush to conclusions: through some pipes you can still see stars during the day. In this case we are talking about astronomical tubes - telescopes.

What's the matter? Why does a “tube with lenses” allow you to see stars during the day, but a simple tube does not?

First of all, let's think about why the stars are not visible during the day? The answer is quite obvious: simply because the daytime sky is bright due to sunlight scattered by the atmosphere. If for some reason this background weakens, for example, a total solar eclipse occurs, then the bright stars and planets will be perfectly visible during the day. They are also clearly visible in open space or from the surface of the Moon, where the sky is completely black and there is no background light. Why does the sunlight scattered in the earth's atmosphere hide the stars from us? After all, their own light does not weaken.

To understand this, you need to imagine our point of view. As you know, the main lens, the pupil, creates an image on the back wall of the eye surface, covered with a light-sensitive layer - the retina, which consists of a large number of elementary light receivers - cones and rods. They are sensitive to light in different ways, but this is not important for us now, and therefore, for simplicity, we will call them all cones. The important thing is that each cone transmits information to the brain about the flow of light falling on it, and the brain synthesizes from these individual messages (signals) a whole picture of what it saw.

The eye is a very complex receiver of information, and in some ways it is similar to a smart electronic device, such as a radio. It has an automatic gain control that makes it sensitive in bright light and increases it in the dark. It also has a noise reduction system that smoothes out random fluctuations in the light flux, both in time and across the surface of the retina. This one has certain threshold characteristics, so it does not notice rapid changes in the image (cinema principle) and small fluctuations in brightness.

When we observe a star at night, the flux of light from it per cone, although small, is significantly greater than the flux from the dark sky falling on neighboring cones. Therefore, it records this as a significant signal. But during the day, so much light from the sky falls on the cones that a small addition in the form of starlight per one of these elements is not felt and is “written off” as fluctuations.

It is quite easy to see that it is the bright background of the sky that hides the stars from us. Here is an experiment on this matter that Yakov Perelman advises to conduct in his “Entertaining Astronomy” (Gostekhizdat, 1949, p. 155):

“A simple one can clearly clarify the disappearance of stars in the daytime sky. To carry it out, several holes are punched in the side wall of a cardboard box, located like some kind of constellation, and a sheet of white paper is glued to the outside. The box is placed in a dark room and illuminated from the inside: holes illuminated from the inside then clearly appear on the broken wall - these are stars in the night sky. But one has only to light a sufficiently bright lamp in the room, without stopping the illumination from within, and the artificial stars on the piece of paper disappear without a trace: it is “daylight” that extinguishes the stars.”

A star can become visible against the background of the daytime sky only if the flux of light from it is comparable to the flux from the sky area that the pupil projects onto one cone. Note that the angular size of this area is called human resolution and is about 1 arc minute.

Of all the star-shaped objects, only Venus is sometimes visible in the daytime sky. It’s not easy to see it: the sky must be perfectly clear, and you need to know approximately where in the sky it is currently located. All other planets and stars have a brightness much weaker than that of Venus, so it is completely impossible to find them without a telescope during the day. However, some astronomers claim that under ideal conditions they were able to observe Jupiter during the day, which is several times fainter than Venus. But no one has yet been able to observe the brightest star in our sky, Sirius, during the day from sea level. True, they say that she was seen high in the mountains, against the backdrop of a dark purple sky.

What does a telescope do that allows us to easily observe night stars during the day? Obviously, the telescope lens collects much more light than the pupil of the eye. But in this sense, the images of the star and the sky are equivalent - when observed through a telescope, the flow of light from them into the eye increases by the same number of times, approximately equal to the ratio of the area of ​​the lens to the area of ​​the pupil. In this case, something else is much more important - the telescope improves the resolution of the eye: after all, it increases the angular size of the observed objects. Moreover, the area that is projected onto one cone during observations with the naked eye is projected onto several cones at once into the telescope, which means that each of them receives proportionally less light (for example, if the telescope increases the angular diameter of objects by A times, then the observed brightness the sky decreases by A2 times). However, the star has a very small angular size, and its light still falls on a single cone. Thus, the light of the star already appears “solid” against the background of the reduced brightness of the sky. And she's noticeable.

What happens: take a telescope with high magnification and you can view the faintest stars during the day? No, that's not true. The Earth's atmosphere is inhomogeneous, so the image of the star is blurred and has a very definite angular size, although very small. At night, in good weather, high in the mountains it is about 1 arc. sec. And during the day at sea level - at least 2–3 arc. sec. Therefore, the maximum magnification we can use will be determined so that the star is still a point source. It is approximately 30–60 times. There is no point in a stronger magnification: the image of the star will be projected onto several cones at once, and will begin to weaken in the same way as the brightness of the sky.

Let's evaluate how faint stars become visible during the day using a telescope. In clear weather, the daytime sky has a brightness of approximately -5m per square minute of arc, that is, approximately one cone. The magnitude of Venus is about -4m. Therefore, we will consider that a star is visible if its brightness is no more than one magnitude less than the surface brightness of the sky per square minute. Using a telescope with a magnification of, say, 45 times, we will achieve a decrease in the brightness of the sky background compared to the brightness of the star by 452 (about 2000 times), that is, by about 8m. This means that in the telescope field the brightness of the sky will decrease to +3m per square minute, and thus stars up to +4m will become available to us. Astronomical observations show that this is indeed the case.

We've dealt with the telescope, now let's go back to the well. Can a well reduce the brightness of the sky for an observer inside it so that the stars can be seen from it? In principle, purely geometrically, perhaps, blocking the entire field except for a small area, the flux of light from which will be comparable to the flux of light from a star. But for this to happen, the hole must be visible at an angle of less than one minute to an observer sitting at the bottom of the well. With a well diameter of 1 m, its depth will be more than 1/sin1"=3.4 km! In this case, the hole of the well will be visible to the observer only as a bright point, the brightness of which will increase only for a moment if any star passes exactly through the zenith. With all the desire It is difficult to consider this procedure as “observation of the starry sky.”

The tall tube can also be used for daytime stargazing. After all, it creates an air channel in which there is practically no diffused sunlight. And if this pipe passes through the entire thickness of the atmosphere, then through it we will be able to see the stars at any time of the day! However, it is worth considering that almost the entire mass of air is contained in the surface layer of the atmosphere about 20 km thick. It must be a long pipe!

Thus, the belief about observing stars during the day from a deep well, as well as from a high chimney, turned out to be a myth. However, where did he come from? One can only guess about this. Perhaps, while at the bottom of a well or mine, someone actually noticed Venus passing across the sky. But this is very unlikely and, in principle, possible only in tropical countries, where Venus is visible at its zenith. It is more plausible that, having descended into a well or a deep cave, people noticed specks of dust illuminated by the Sun against the background of dark walls. Perhaps they were mistaken for stars.

An absolutely enchanting failure of propaganda of the “space program”, in which different astronauts directly contradict each other, answering the same question.
Some say that the stars are NOT visible, others enthusiastically talk about bright space with clearly visible planets and satellites.

Particularly touching is the picture of absolutely empty “space” that accompanies the brave descriptions of countless stars.

I emphasize the point: in none of the shown segments are the stars visible, although some heroes talk about them as a self-evident fact, which their colleagues immediately refute.

Are stars visible in space and on the Moon? The astronauts answer.

Pay attention to the behavior of the three FIRST people in HISTORY who just returned from the Moon.

If you were walking around another world a couple of days ago, would you sit with such sour faces, nervously fiddling with your hands and trying to remember quite simple details?

This is actually some kind of performance, not an interview.

They suck the answers out of their fingers as they go

And where are these countless stars who went out to smoke? 0_o

Here we are talking about some designer who could not repeat the black color of the infinite universe.

Which designer are we talking about and what exactly he couldn’t repeat - curtains with tulle in those. compartment or graphics of the clip we are watching?

What's the point of making graphics if you can just film everything on camera, except to hide the real state of affairs?

So who to believe, comrades?

Maybe they live in different worlds or fly to different spaces?

Maybe some have dirty windows, while others have illuminated ones?

Maybe they are being given different amusing gases, oxygen, or the canned food has gone bad?

Maybe they are under hypnosis, because schizophrenics wouldn’t be allowed into space, right?

Or are they still feeding us blatant nonsense about space, without really bothering with the contradictions?

It will be interesting to know the arguments of the respected and polite skeptics about this.

On this topic:

Reality is multidimensional, opinions about it are multifaceted. Only one or a few faces are shown here. You should not take them as the ultimate truth, because truth is limitless, and each level of consciousness has its own picture of the world and level of information processing. We learn to separate what is ours from what is not ours, or to obtain information autonomously)

Many of us were interested in why stars are not visible in the sky during the day. After all, they do not disappear anywhere, do not move away, but the human eye is still not able to see them in the light of the sun. Scientists have long figured out this issue, but, nevertheless, many people still have difficulty understanding the reasons for this phenomenon.

Stars and sun

Each star is an impressively sized ball of gas that emits its own light. This is a key difference from planets and satellites: they create light by reflecting the sun's rays on their surface, while stars have their own glow (because they have nothing to reflect the sun's rays with).

This is the main reason why they are not visible during the day. In addition to this, it is worth considering some other nuances:

1. The planet has an atmosphere.

There are a large number of elements in the atmosphere. These are carbon dioxide, hydrogen and dozens of other gaseous substances (including water molecules) that cannot be seen with the naked eye.

When the sun's rays pass through the atmosphere, they have a specific color depending on the color wavelength:

• blue, violet and cyan colors (blue sky) have short waves;
• and long ones are red (sunset).

The sun is also a star, but its rays are so bright that they literally outshine the glow of any other stars and even planets. All other objects in space cannot be seen either, since their glow is much weaker than that of the sun.

1. During the day, when the Sun illuminates the Earth, the sun's rays are scattered and refracted.

Thus, the stars cannot be seen during the day, even if you move to another point on the planet (due to the scattering of rays in the atmosphere). The presence of the mentioned elements in the air is also of great importance:

• microscopic dust does not retain blue light from the sun;
• the presence of molecules of a certain gas (for example, red phosphorus) also affects the color scheme.

1. With such a wide range of shades of different colors, it is literally impossible to see the stars.

The reason for this is the presence of many light sources (which are created by the sun). Therefore, the glow of stars simply does not reach the surface of the planet, and if it does, the scattered rays of the Sun completely neutralize its impact. This is why stars cannot be seen during the day.

On the other hand, people can still see one star in daylight. But only the brightest of all possible – just the Sun.

Why are no other stars visible from behind the Sun?

It's very simple: the Sun is the only star in our solar system. All other stars are located much further, beyond its boundaries. That is why they cannot be seen during the day - they are too far away, and their radiance is interrupted and scattered under the influence of the sun's rays.

The Sun also consists of several layers that distinguish it from other (studied) stars. Yes, it consists of gases, but around it there is a constantly moving atmosphere, which exceeds the diameter of the Sun itself by 3 and even 4 times. This outer atmosphere is only the first layer of many others that make up the Sun.

Taking all this into account, the fact is once again confirmed that the stars cannot be seen during the day because of this “giant”, which, due to its structure, emits such a bright glow that it is impossible to interrupt it with anything.

At the same time, the structure of the human eye also influences:

• at night, in the open air, you can spend hours admiring the stars in the sky;
• but even 3 seconds of looking directly at the sun will be enough to radically damage your vision, and 6 seconds to require surgery to restore the structure of the eyeball.

Thus, it is again confirmed that the Sun is much brighter than other stars. And it also becomes clear that a person cannot use his eyes in such a way as to focus not on the rays of the Sun, but on more distant objects.

Although this will not be enough, because due to the refraction and scattering of light, the remaining stars completely merge with the sky, the rays of the sun and the molecules of substances. Even technology will not be able to see the stars during the day, let alone human vision?

How can you see stars during the day?

Ancient scientists, Aristotle and Pliny, wrote in their works that stars can be seen during the day from a deep well, cave or long chimney. This is a fairly common opinion: some claim that this is the true truth, and some call such sayings universal stupidity.

A more modern example is Robert Ball, who in 1889 claimed that he was able to see several stars in the daytime sky while standing in a long chimney. He believed that in a dark narrow pipe, the vision of any person becomes much clearer.

And this makes some sense: once you get from the light into a dark room, it is impossible to see anything. But once your eyes get used to the darkness, you can easily distinguish objects in the room.

However, unfortunately, there are no reliable facts that could confirm this theory. But many people hastened to refute it. Here are the most famous of them:

• Alexander Humboldt, at different times in his life, descended into the deepest mines of America and Siberia, but he was unable to discover any stars;
• Leonid Repin (journalist for Komsomolskaya Pravda) descended to the bottom of a 60-meter well in 1978, but looking up he found only a small piece of the daytime sky, of course, without any stars.

As a result, scientists came to the conclusion that ancient naturalists could perceive small specks of dust as stars, which rose upward (due to the observer’s descent) and slowly floated against the background of the visible sky. In a dark mine, well or other dark room, sunlight reflects very beautifully on tiny objects. As a result, such a phenomenon could be perceived as stars, although in reality it is not so.

It turns out that there is no way to see the stars during the day? It turns out that there is, but it is impossible to repeat such an experiment in laboratory conditions. That is, it will not be possible to recreate a similar situation with human forces and resources - a solar eclipse.

The same thing during which the moon comes between the human gaze and the sun. At this moment, the minimum amount of light reaches the Earth and it becomes unnaturally dark right in the middle of the working day. Due to the fact that sunlight does not reach the planet, the radiance of distant stars will no longer be refracted or scattered, and the stars can be seen during the day.

Are stars visible during the day (video)?

From this video you will learn whether it is possible to see stars during the day, how the human eye works and perceives light, and why only the Sun star is visible in the sky during the day.

It turns out that technically the stars can still be seen during the daytime. However, this cannot be done in other ways due to the laws of physics and the structure of the human eyeball. The scattering of light and refraction of rays from distant objects in space does not allow them to be seen even through a telescope. Especially when this is interfered with by the radiation of our Sun.