Since ancient times, people have looked at the night sky and marveled at how densely it is dotted with stars. The number of shining dots in the sky has worried mankind for thousands of years.


Ever since the time Ancient Greece scientists tried to count the stars, but even now, in the age of high technology and ultra-precise instruments, modern astronomers can only approximately answer the question of how many there really are.

The first catalog of stars in our history was compiled by the astronomer Hipparchus. Using a primitive telescope, he was able to detect about 1000 celestial bodies and determine their exact coordinates. It is he who owns the concept of "stellar magnitudes", which astronomers use to this day.

The essence of this system lies in the fact that all objects in the Universe are located at different observable magnitudes - the brighter the star, the smaller its magnitude. Initially, he broke all the stars into 6 magnitudes. The last, sixth, were the least bright, which can hardly be seen with human vision. In the future, scientists discovered many other quantities that are visible only with the help of special instruments.

How many stars are in six magnitudes? In other words, how many stars can we see at night with the naked eye? It is believed that people with perfect vision see no more than 5-6 thousand at the same time in both hemispheres.

In one hemisphere, only 2-3 thousand celestial bodies are visible, however, due to artificial lighting at night and reducing the transparency of the atmosphere near the horizon in major cities this number is reduced tenfold. With binoculars you can see up to 200 thousand stars, with an amateur telescope - about 10 times more.

solar system is one of the planetary systems of our galaxy and includes only one star -. All other objects in it are planets, satellites, asteroids, comets and other cosmic bodies. The sun appeared about 4.57 billion years ago and this moment is in the prime of his life.


Its mass is so great that it easily holds near itself and makes all smaller objects move. Unlike other stars, you can see the Sun not at night, but during the day, because at night it disappears below the horizon.

The galaxy in which our planet is located. In addition to the Sun, it is supposed to include 200 billion stars, although some scientists suggest that their number reaches 400 billion. In the pictures of the sky taken by the most powerful telescopes, you can see so many stars that astronomers consider it pointless to count them and give names.

Only 0.01% of all stars in the Milky Way are numbered and cataloged, and even fewer have names - only about 300 stars. As a rule, names are assigned only to the largest and brightest objects, such as Sirius, the North Star, Antares, Proxima Centauri.

Many star names (Aldebaran, Rigel, Algol) astronomers learned from folk tales, parables or legends. Some stars were named after the astronomers who first described them - Bernard's star, Kapteyn's star.

No one knows the number of stars in the universe. It is infinite and in its observable part (seen in the Hubble telescope) contains about a trillion galaxies. There are approximately 200 billion stars in the Milky Way, but there are galaxies that are 20 times larger than ours.

Each of them contains many hundreds of billions of stars, so it is not possible to count them. According to scientists, on average, about 10 24 (10 to the 24th power) stellar objects are available for observation, although it is possible that this number is much higher.

The work of the Hubble orbiting telescope has provided the first solid data to estimate the number of stars in the universe

The Hipparcos mission has recorded many millions of stars in our galaxy alone - and this is clearly not the limit.

The new Herschel telescope will be able to see the most distant stars in their infrared radiation. Its launch, unfortunately, has been delayed year after year, and is currently scheduled for spring 2009.

If you leave the illuminated city streets and look at the sky above your head on a fairly dark and cloudless night, it seems that myriads of stars will open. In fact, only a few thousand are visible to the naked eye - and even the simplest amateur telescope increases this number by orders of magnitude.

Modern instruments are discovering more and more distant galaxies, full of countless new stars, and it seems that there will be no end to this ... But how many of them, after all? Even for experts, it is not easy to answer this question. Let's try to figure it out.

Indeed, the stars are not distributed throughout the universe in a uniform "suspension", they are collected in large groups - galaxies. For example, our Sun is located in the Milky Way galaxy, and in total there are about 100 billion stars in it alone. But there are trillions of galaxies in the universe alone!

The ancient sage said that trying to count the stars is tantamount to counting all the grains of sand on all the coasts on the whole Earth. But if we do not need an exact number, but rather a rough estimate, then we can take satellite images, set approximately total area suitable coastline, find out the average thickness of the sand layer and, knowing the volume of all sand on Earth, divide it by the average volume of a grain of sand. It is not easy to get a rough figure, but it is possible.

If we return to heaven, then galaxies can act as such “beach” for us: it is approximately established that in our galaxy 1011−1012

stars, and in the Universe - 1011−1012 galaxies. A simple calculation shows that there should be 1022-1024 stars in the universe.

This, of course, is a rough figure, suggesting that our galaxy is quite average, that deviations from medium size small, and that we correctly estimated the number of galaxies in the universe. And the latter can be very misleading, because for a long time it was believed that there were about 50 billion galaxies, and only the work of the Hubble orbiting telescope increased this figure by 2.5 times!

And even Hubble doesn't see everything. Except for particularly distant or dim galaxies, many of them are simply invisible to a telescope operating in the optical range: they are obscured by a dense cloud of gas and dust that accompanies the process of active star formation. The Herschel infrared probe, which is preparing to launch this spring, will allow you to look into these distances (we talked about how it will work in the article “ Big-eyed”).

At the same time, it should be taken into account that no one has ever actually taken to count the number of stars in a galaxy: some generalizing characteristic is usually measured, in particular, the luminosity of a galaxy. Then we can, roughly speaking, divide the luminosity of the galaxy by the average luminosity of a star at the same distance - and estimate the number of stars in it. Herschel will work in approximately the same way, "counting" galaxies and measuring their luminosity in the IR range.

So you just have to wait - until you can say that the stars are not less than the above value: 1,000,000,000,000,000,000,000,000, that is, a trillion trillion.

Optical instruments that shorten the distance to the stars - binoculars, amateur and powerful professional telescopes - open up an endless series of celestial bodies. To the naked eye away from the lights big cities opens about two thousand stars. This is a third of the total visible in the two hemispheres of the planet. Out of view are the stars of the opposite hemisphere and those that are located near the horizon - where the transparency of the atmosphere decreases.

Named stars

The brightest and largest stars have several: each people of the Earth gave them their names. The names of about 300 of them have survived to our times - with Sumerian, Akkadian, Coptic, Semitic, Greek, Roman and, of course, Arabic roots. However, on the maps of the starry sky, the luminaries are indicated by the letters of the Greek alphabet with belonging to. The lower the brightness of the star, the farther from the beginning of the alphabet denoting it.

The star Deneb (“tail” in Arabic), the “alpha” of the constellation Cygnus, has several “namesakes” - from the constellations Kita (Deneb Kaitos), Leo (Denebol), Scorpio (Deneb Akrab), Dolphin and Eagle.

About two dozen astronomers who discovered or described them are named. Such are Barnard's flying star in the constellation Ophiuchus and Kapteyn's star in the constellation of the Painter, invisible to the naked eye and opened using powerful optical instruments. The pomegranate star Herschel in the constellation Cepheus is available for observation in the Northern Hemisphere. The names of the astronomers Van Maanen, Krzeminsky, Przybylsky, Popper, Leyten, Teegarden also accompany the mention of the stars they described. However, this one is unofficial. It is not easy to remember how many pioneers from other fields of science are characterized by the same modesty.

The cunning founders of companies that offer to name a star after someone who wants to pay money for it successfully make money out of thin air. There will be no information about the name in the official star atlases, and only two parties will know about the existence of a certificate on assigning a new name to the star - the one who paid and the one who accepted the payment.

Nameless stars

After about 6,000 stars visible to the naked eye, objects visible through binoculars follow. With this increase, the number of stars grows to 200 thousand. According to the system of stellar magnitudes developed by the ancient Greek astronomer Hipparchus of Nicaea and improved today, these are stars of magnitude 9-10.

Stars 11-12 magnitude eyepiece of a modest amateur telescope, and their number increases to 2 million. A powerful telescope allows objects up to 15-16 magnitude, increasing their number by more than 100 million.

It is believed that the number of stars up to magnitude 20 is in the tens of billions. However, not all of them are in constant visual availability (through telescopes, of course), periodically covered by clouds of cosmic dust. How many stars are even further away, you can only figure out approximately.

In the Atacama Desert (Chile) operates the most powerful telescope on Earth, a complex of 4 main and 4 auxiliary optical telescopes. It is called - Very Large (Very Large Telescope), or VLT.

According to astronomers

At night, far from the blinding lights of cities, the sky reveals a breathtaking picture of hundreds of stars scattered across the constellations and the Milky Way. It seems impossible to count them yourself - the numbers seem fantastic, from millions to billions. But it immediately comes to mind that this is exactly what astronomers should be doing. So how many stars are there really in the sky? Today we will try to determine the exact number.

Stars visible to the eye

We have heard more than once that there are trillions of stars in the Universe alone. But there is a nuance - not all of them are visible to a person. It's all about the brilliance, or - dim luminaries near look brighter than very powerful ones in the distance. How less stars The higher the value, the better the star is visible - but there is a limit beyond which even the most keen eye will not distinguish the star. The bar for the human eye is magnitude +7. The specific value fluctuates between +6 and +8 depending on the visual acuity and the darkness of the sky.

As a result, out of the entire vast number of stars, a person can see in the sky ... only 6000! But this is also an approximate number. As we already know, the celestial sphere is divided into two hemispheres, in each of which up to 3000 stars are visible. Moreover, some of the stars are near the horizon, where it is very difficult to observe them - they are hidden by a dense one. And we also need to make allowances for reality, where there is no perfectly flat horizon. It is constantly complicated by trees, buildings, hills and other uneven terrain, reducing the number of simultaneously visible stars to 2500.

  • An interesting fact - all these obstacles lead to the fact that large observatories are built in the mountains, at a distance from the settlements. There the atmosphere is not so dense, and the horizon on the very high mountain more available. Mountains near the sea or ocean are especially popular: the water surface is probably the only flat horizon in the world.

But even this number is available at ideal conditions observations - that is, a dark moonless night. In summer, the sky near the edges is brighter than in winter, and any city lamp creates a flare. in the middle big city the number of stars in the heavens drops immediately to 200-300. Hence, best view on the stars opens only in winter, at a distance of more than 5 kilometers from any locality or illuminated road.

Stars in a telescope, or the total number of stars in the sky

However, humanity has long found a way to circumvent the limitations of their own vision. Many powerful telescopes on Earth and in space daily push the visible boundaries of space, discovering new stars and galaxies. Even the most ordinary binoculars make it possible to see an additional 200,000 stars. A cheap one opens 10 times more luminaries!

Of course, we cannot see all the stars in the universe. The center of our galaxy is an insurmountable barrier that closes part of milky way, and clouds of cosmic dust absorb all rays except infrared. And although astronomers struggle with this - so, the telescope will penetrate those obstacles that were previously considered insurmountable - the universe remains limited. At least in appearance - the maximum distance we can look at is 45.7 billion light years.

Let's sum up the final score. There are approximately 100 to 400 billion stars in our galaxy. According to the telescope, about 100 billion galaxies have now been found, and it is believed that another 100 billion will be found soon. Our galaxy is traditionally considered average in terms of the number of stars it can contain - there are objects both larger and smaller.

Let's use the known numbers and count the number of stars in the sky together. We have 100 billion galaxies, each containing 100-400 billion stars. Multiply 10 11 by 10 11 - you get 10 22 stars, 10000000000000000000000 stars in the sky. And that's just the bare minimum! If there are more galaxies or stars, the number will increase by orders of magnitude.

Because of all these conventions and inaccuracies, astronomers rarely undertake to give an accurate estimate of the number of stars in the sky. There are simply too many of them, and not everything can be clearly seen and separated from the rest. Especially in distant galaxies - often they themselves look like one dim star.

Attempts to count the stars in the sky have been made since ancient times. Apparently, it is human nature to systematize and sort everything. The oldest known star catalog was compiled by the ancient Roman astronomer Hipparchus, and this was two and a half thousand years ago. It was he who introduced the concept of "star magnitude", which is still used today. Magnitude is not the size of a star, as you might think from this word. This is her brightness.

Hipparchus divided all the stars according to their brightness into six stellar magnitudes, of which the sixth was the weakest, visible at the limit of human vision. Then, with the development of optics, the seventh, and the tenth, and the fifteenth magnitude appeared ... Such stars cannot be seen with the naked eye at all, only with a telescope of the appropriate power. Through binoculars you can see stars no more than the eighth or ninth magnitude, by the way.

So how many stars can you see without instruments?

Let's go outside and look at the sky, if it is, of course, clear and clean. Impressive immediately great amount stars. But this feeling is somewhat misleading. In fact, a person with excellent vision will not be able to see more than 5-6 thousand stars in both hemispheres together, and in one - no more than 2.5-3 thousand. That is how many stars with brightness up to the 6th magnitude are in the sky.

In fact, we will see much less, and there are reasons for this.

For example, at the zenith one can see more stars, including the weak ones. This can be explained by a thinner layer of the atmosphere when looking straight up, and, accordingly, by less refraction of light and its absorption in dusty and foggy air. Stars closer to the horizon will be less visible. Low to it, we will not be able to see a star of the 6th magnitude by any means, it’s good if we can see the 4th. But the area of ​​the sky at the horizon is much larger than the area at the zenith.

In addition, there are many more faint stars than bright ones, and we will be able to see only a small part of them. Therefore, in fact, a person, even with perfect vision, will be able to see no more than 1.5 - 2 thousand stars in the sky. And this is clearly less than we expected.

It is worth remembering that the more extraneous lighting, the less stars you can see. Everyone has been to cities and probably noticed that the stars are almost invisible there, even in seemingly dark places. So - a few of the brightest, and that's it! The illumination of the sky by street lamps, the light of cars, thousands of windows interferes ... In such conditions, looking at the stars is the same as through a window from a room with the lights on. There are also far fewer stars visible when the moon is in the sky, and the brighter it is, the fewer stars are visible.

And how many stars are there in the sky?

Not only visible to the naked eye, but also invisible? There is no answer here, and there cannot be - the Universe is infinite, there are an infinite number of stars in it, moreover, every second some of them die, others appear. Life is in full swing in the universe, it would seem slow in our understanding, but on what scale!

It is worth noting simply that with each magnitude, about three times as many stars are visible. For example, with binoculars you can already see about 200 thousand stars. An average amateur telescope can already see up to 100 million stars up to magnitude 15-16.

If we go even further and arm ourselves with the most modern devices invented by man today, then we will be able to see a much larger piece of the Universe. We can even see individual stars in other galaxies. Then we can count already 70 sextillion stars. It's 7 and 22 zeros!

In fact, as soon as a person invents even more powerful devices, the boundary of the visible part of the Universe is still receding, and the number of new stars increases many times over. After all, there are an infinite number of stars in the sky!