- Translation
Do you know them all, as well as the reasons for their brightness?
I'm hungry for new knowledge. The point is to learn every day and become brighter and brighter. This is the essence of this world.
- Jay-Z
When you imagine the night sky, you most likely think of thousands of stars twinkling against the black blanket of night, something that can only be truly seen away from cities and other sources of light pollution.
But those of us who don't get to witness such a spectacle on a periodic basis are missing the fact that stars seen from urban areas with high light pollution look different than when viewed in dark conditions. Their color and relative brightness immediately set them apart from their neighboring stars, and each has its own story.
People in the northern hemisphere can probably immediately recognize Ursa Major or the letter W in Cassiopeia, while in the southern hemisphere the most famous constellation has to be the Southern Cross. But these stars are not among the ten brightest!
Milky Way next to the Southern Cross
Each star has its own life cycle, to which it is tied from the moment of birth. When any star forms, the dominant element will be hydrogen - the most abundant element in the Universe - and its fate is determined only by its mass. Stars with 8% the mass of the Sun can ignite nuclear fusion reactions in their cores, fusing helium from hydrogen, and their energy gradually moves from the inside out and pours out into the Universe. Low-mass stars are red (due to low temperatures), dim, and burn their fuel slowly—the longest-lived ones are destined to burn for trillions of years.
But the more mass a star gains, the hotter its core, and the larger the region in which nuclear fusion occurs. By the time it reaches solar mass, the star falls into class G, and its lifetime does not exceed ten billion years. Double the solar mass and you get a class A star that is bright blue and lives for less than two billion years. And the most massive stars, classes O and B, live only a few million years, after which their core runs out of hydrogen fuel. Not surprisingly, the most massive and hot stars are also the brightest. A typical class A star can be 20 times brighter than the Sun, and the most massive ones can be tens of thousands of times brighter!
But no matter how a star begins life, the hydrogen fuel in its core runs out.
And from that moment on, the star begins to burn heavier elements, expanding into a giant star, cooler, but also brighter than the original one. The giant phase is shorter than the hydrogen burning phase, but its incredible brightness makes it visible from much greater distances than the original star was visible from.
Taking all this into account, let's move on to the ten brightest stars in our sky, in increasing order of brightness.
10. Achernar. A bright blue star with seven times the mass of the Sun and 3,000 times the brightness. This is one of the fastest rotating stars known to us! It rotates so fast that its equatorial radius is 56% greater than its polar radius, and the temperature at the pole - since it is much closer to the core - is 10,000 K higher. But it is quite far from us, 139 light years away.
9. Betelgeuse. A red giant star in the Orion constellation, Betelgeuse was a bright and hot O-class star until it ran out of hydrogen and switched to helium. Despite its low temperature of 3,500 K, it is more than 100,000 times brighter than the Sun, which is why it is among the ten brightest, despite being 600 light years away. Over the next million years, Betelgeuse will go supernova and temporarily become the brightest star in the sky, possibly visible during the day.
8. Procyon. The star is very different from those we have considered. Procyon is a modest F-class star, just 40% larger than the Sun, and on the verge of running out of hydrogen in its core - meaning it is a subgiant in the process of evolution. It is about 7 times brighter than the Sun, but is only 11.5 light years away, so it may be brighter than all but seven stars in our sky.
7. Rigel. In Orion, Betelgeuse is not the brightest of the stars - this distinction is awarded to Rigel, a star even more distant from us. It is 860 light years away, and with a temperature of just 12,000 degrees, Rigel is not a main sequence star - it is a rare blue supergiant! It is 120,000 times brighter than the Sun, and shines so brightly not because of its distance from us, but because of its own brightness.
6. Chapel. This is a strange star because it is actually two red giants with temperatures comparable to the Sun, but each is about 78 times brighter than the Sun. At a distance of 42 light years, it is the combination of its own brightness, relatively short distance and the fact that there are two of them that allows Capella to be on our list.
5. Vega. The brightest star from the Summer-Autumn Triangle, the home of the aliens from the film “Contact”. Astronomers used it as a standard "zero magnitude" star. It is located only 25 light years from us, belongs to the stars of the main sequence, and is one of the brightest class A stars known to us, and is also quite young, only 400-500 million years old. Moreover, it is 40 times brighter than the Sun, and the fifth brightest star in the sky. And of all the stars in the northern hemisphere, Vega is second only to one star...
4. Arcturus. The orange giant, on the evolutionary scale, is somewhere between Procyon and Capella. It is the brightest star in the northern hemisphere and can be easily found by the "handle" of the Big Dipper. It is 170 times brighter than the Sun, and following its evolutionary path, it can become even brighter! It is only 37 light years away, and only three stars are brighter than it, all located in the southern hemisphere.
3. Alpha Centauri. This is a triple system in which the main member is very similar to the Sun, and is itself fainter than any star in the ten. But the Alpha Centauri system consists of the stars closest to us, so its location affects its apparent brightness - after all, it is only 4.4 light years away. Not at all like number 2 on the list.
2. Canopus. A white supergiant, Canopus is 15,000 times brighter than the Sun, and is the second brightest star in the night sky, despite being 310 light-years away. It is ten times more massive than the Sun and 71 times larger - it is not surprising that it shines so brightly, but it could not reach the first place. After all, the brightest star in the sky is...
1. Sirius. It is twice as bright as Canopus, and northern hemisphere observers can often see it rising behind the constellation Orion in winter. It flickers frequently because its bright light can penetrate the lower atmosphere better than that of other stars. It's only 8.6 light-years away, but it's a class A star, twice as massive and 25 times brighter than the Sun.
It may surprise you that the top stars on the list are not the brightest or the closest stars, but rather combinations of bright enough and close enough to shine the brightest. Stars located twice as far away have four times less brightness, so Sirius shines brighter than Canopus, which shines brighter than Alpha Centauri, etc. Interestingly, class M dwarf stars, to which three out of every four stars in the Universe belong, are not on this list at all.
What we can take away from this lesson: sometimes the things that seem most striking and most obvious to us turn out to be the most unusual. Common things can be much harder to find, but that means we need to improve our observation methods!
Not only astronomers and romantics love to look at the sky. We all look up to the stars from time to time and admire their eternal beauty. That is why each of us is at least sometimes interested in which star in the sky is the brightest.
The Greek scientist Hipparchus first asked this question, and he proposed his classification 22 centuries ago! He divided the stars into six groups, where the first magnitude stars were the brightest he could observe, and the sixth magnitude were those barely visible to the naked eye.
Needless to say that we are talking about relative brightness, and not about the actual ability to glow? Indeed, in addition to the amount of light produced, the brightness of a star observed from Earth is affected by the distance from this star to the observation site. It seems to us that the brightest star in the sky is the Sun, because it is closest to us. In fact, it is not at all a bright and very small star.
Nowadays, approximately the same system for distinguishing stars by brightness is used, only improved. Vega was taken as the reference point, and the brightness of the remaining stars is measured from its indicator. The brightest stars have a negative index.
So, we will consider exactly those stars that are recognized as the brightest according to the improved Hipparchus scale
10 Betelgeuse (α Orionis)
The red giant, with 17 times the mass of our Sun, rounds out the top 10 brightest night stars.
This is one of the most mysterious stars in the Universe, because it is capable of changing its size, while its density remains unchanged. The color and brightness of the giant varies at different points.
Scientists expect Betelgeuse to explode in the future, but given that the star is located at a huge distance from the Earth (according to some scientists - 500, according to others - 640 light years), this should not affect us. However, for several months the star can be seen in the sky even during the day.
9 Achernar (α Eridani)
A favorite of science fiction writers, a blue star with a mass 8 times greater than that of the Sun looks very impressive and unusual. The star Achernar is flattened so that it resembles a rugby ball or a tasty torpedo melon, and the reason for this is a fantastic rotation speed of more than 300 km per second, approaching the so-called separation speed, at which the centrifugal force becomes identical to the force of gravity.
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Around Achernar you can observe a luminous shell of star matter - this is plasma and hot gas, and the orbit of Alpha Eridani is also very unusual. By the way, Achernar is a double star.
This star can only be observed in the Southern Hemisphere.
8 Procyon (α Canis Minor)
One of the two “dog stars” is similar to Sirius in that it is the brightest star in the constellation Canis Minor (and Sirius is the brightest star in Canis Major), and in that it is also double.
Procyon A is a pale yellow star about the size of the Sun. It is gradually expanding, and in 10 million years it will become an orange or red giant. According to scientists, the process is already underway, as evidenced by the unprecedented brightness of the star - it is more than 7 times brighter than the sun, although similar in size and spectrum.
Procyon B, its companion, a dim white dwarf, is about the same distance from Procyon A as Uranus is from the Sun.
And there were some mysteries here. Ten years ago, a long-term study of the star was undertaken using an orbiting telescope. Astronomers were eager to get confirmation of their hypotheses. However, the hypotheses were not confirmed, and now scientists are trying to explain what is happening on Procyon in some other way.
Continuing the “dog” theme – the name of the star means “in front of the dog”; this means that Procyon appears in the sky before Sirius.
7 Rigel (β Orionis)
In seventh place in terms of relative (observed by us) brightness is one of the most powerful stars in the Universe with an absolute magnitude of -7, that is, the brightest of the stars located more or less nearby.
It is located 870 light years away, so less bright but closer stars appear brighter to us. Meanwhile, Rigel is 130 thousand times brighter than the Sun and 74 times larger in diameter!
The temperature on Rigel is so high that if something were to be at the same distance from it as the Earth is relative to the Sun, this object would immediately turn into a stellar wind!
Rigel has two companion stars, almost invisible in the bright glow of the blue-white supergiant.
6 Chapel (α Auriga)
Capella ranks third among the brightest stars in the Northern Hemisphere. Of the stars of the first magnitude (the famous Polaris is only of the second magnitude), Capella is located closest to the North Pole.
This is also a double star, and the weaker of the pair is already becoming red, and the brighter is still white, although the hydrogen in its body has obviously already turned into helium, but has not yet ignited.
The name of the star means Goat, because the Greeks identified it with the goat Amalthea, who suckled Zeus.
5 Vega (α Lyrae)
The brightest of the Sun's neighbors can be observed throughout the entire Northern Hemisphere and almost the entire Southern Hemisphere, except Antarctica.
Vega is beloved by astronomers for being the second most studied star after the Sun. Although there is still a lot of mystery in this “most studied” star. What can we do, the stars are in no hurry to reveal their secrets to us!
Vega's rotation speed is very high (it rotates 137 times faster than the Sun, almost as fast as Achernar), so the star's temperature (and therefore its color) differs at the equator and at the poles. Now we see Vega from the pole, so it appears pale blue to us.
Around Vega there is a large cloud of dust, the origin of which is controversial among scientists. The question of whether Vega has a planetary system is also debatable.
4 The brightest star in the Northern Hemisphere is Arcturus (α Bootes)
In fourth place is the brightest star of the Northern Hemisphere - Arcturus, which in Russia can be observed anywhere throughout the year. However, it is also visible in the Southern Hemisphere.
Arcturus is many times brighter than the Sun: if we take into account only the range perceived by the human eye, then more than a hundred times, but if we take the intensity of the glow as a whole, then 180 times! This is an orange giant with an atypical spectrum. Someday our Sun will reach the same stage that Arcturus is at now.
According to one version, Arcturus and its neighboring stars (the so-called Arcturus Stream) were once captured by the Milky Way. That is, all these stars are of extragalactic origin.
3 Toliman (α Centauri)
This is a double, or rather, even a triple star, but we see two of them as one, and the third, dimmer one, which is called Proxima, as if separately. However, in fact, all these stars are not very bright, but are located not far from us.
Since Toliman is somewhat similar to the Sun, astronomers have long and persistently been looking for a planet near it, similar to Earth and located at a distance that makes life on it possible. In addition, this system, as already mentioned, is located relatively close, so the first interstellar flight will probably be there.
Therefore, the love of science fiction writers for Alpha Centauri is understandable. Stanislav Lem (creator of the famous Solaris), Asimov, Heinlein devoted pages of their books to this system; The action of the acclaimed film “Avatar” also takes place in the Alpha Centauri system.
2 Canopus (α Carinae) is the brightest star in the Southern Hemisphere
In absolute terms of luminosity, Canopus is much brighter than Sirius, which, in turn, is much closer to Earth, so that objectively it is the brightest night star, but from a distance (it is located at a distance of 310 light years) it seems dimmer to us than Sirius.
Canopus is a yellowish supergiant whose mass is 9 times the mass of the Sun, and it glows 14 thousand times more intensely!
Unfortunately, it is impossible to see this star in Russia: it is not visible north of Athens.
But in the Southern Hemisphere, Canopus was used to determine their location in navigation. In the same capacity, Alpha Carinae is used by our astronauts.
1 The brightest star in our starry sky is Sirius (α Canis Majoris)
The famous “dog star” (it was not for nothing that J. Rowling called her hero, who turned into a dog, that way), the appearance of which in the sky meant the beginning of vacation for ancient schoolchildren (this word means “dog days”) is one of the closest to the solar system and therefore perfectly visible from almost anywhere on Earth, except the Far North.
It is now believed that Sirius is a double star. Sirius A is twice as large as the Sun, and Sirius B is smaller. Although millions of years ago, apparently, it was the other way around.
Many peoples have left various legends associated with this star. The Egyptians considered Sirius to be the star of Isis, the Greeks - the dog of Orion taken to heaven, the Romans called him Canicula (“little dog”), in Old Russian this star was called Psitsa.
The ancients described Sirius as a red star, while we observe a bluish glow. Scientists can only explain this by assuming that all ancient descriptions were compiled by people who saw Sirius low above the horizon, when its color was distorted by water vapor.
Be that as it may, now Sirius is the brightest star in our sky, which can be seen with the naked eye even during the day!
People have always admired the starry sky. Back in the Stone Age, living in caves and dressing in skins, at night they raised their heads to the sky and admired the glowing lights.
Today the stars still attract our gaze. We know well that the brightest of them is the Sun. But what are the others called? Which stars, besides the Sun, are the brightest?
1. Sirius
Sirius is the brightest star in the night sky. It is not much higher (only 22 times), but due to its proximity to Earth it is more noticeable than others. The star can be seen from almost every corner of the globe, except the northern regions.
In 1862, astronomers discovered that Sirius had a companion star. Both of them revolve around a single center of mass, but only one of them is visible from Earth - Sirius A. According to scientists, the star is gradually approaching the Sun. Its speed is 7.6 km/s, so it will become even brighter over time.
2. Canopus
Canopus is part of the constellation Carina and is second in brightness after Sirius. It belongs to the supergiants, exceeding the Sun in radius by 65 times.
Among all the stars located at a distance of 700 light years from Earth, Canopus has the greatest luminosity, but due to its remoteness it does not shine as brightly as Sirius. Once upon a time, before the invention of the compass, sailors used it as a guiding star.
3. Toliman
Toliman is also called Alpha Centauri. It is actually a binary system with stars A and B, but these stars are so close to each other that they cannot be distinguished with the naked eye. The third brightest in the sky is one of them - Alpha Centauri A.
There is another star in the same system - Proxima Centauri, but it is usually considered separately, and in terms of brightness it is not even included in the 25 stars with the highest luminosity.
4. Arcturus
Arcturus is an orange giant and shines brighter than other stars included in it. In different regions of the Earth it can be seen at different times of the year, but in Russia it is always visible.
According to the observations of astronomers, Arcturus is a variable star, that is, it changes its brightness. Every 8 days its brightness varies by 0.04 magnitude, which is explained by surface pulsation.
5. Vega
The fifth brightest star is part of the Lyra constellation and is the most studied after the Sun. Vega is located at a short distance from the solar system (only 25 light years) and is visible from anywhere on the planet, with the exception of Antarctica and the northern regions of North America.
Around Vega there is a disk of gas and dust, which, under the influence of its energy, emits infrared rays.
6. Chapel
From an astronomical point of view, the star is interesting for its binary system. Capella is two giant stars separated by 100 million kilometers. One of them, called Capella Aa, is old and is gradually beginning to fade. 
The second - Capella Ab - still shines quite brightly, but, according to scientists, the processes of helium synthesis have already ended there. Sooner or later, the shells of both stars will expand and touch each other.
7. Rigel
The luminosity of Rigel is 130 thousand times greater than the Sun. It is one of the most powerful stars in the Milky Way, but due to its distance from the solar system (773 light years), it is only seventh in brightness.
Like Arcturus, Rigel is considered a variable star and changes its brightness at intervals of 22 to 25 days.
8. Procyon
Procyon's distance from Earth is only 11.4 light years. Its system includes two stars - Procyon A (bright) and Procyon B (dim). The first is a yellow subgiant and shines about 7.5 times brighter than the Sun. Due to its age, over time it will begin to expand and shine much better.
It is believed that sooner or later it will increase to 150 times its current size, and then take on an orange or red color.
9. Achernar
In the list of the 10 brightest stars in the sky, Achernar ranks only ninth, but at the same time it is the hottest and the bluest. The star is located in the constellation Eridanus and shines 3000 times brighter than the Sun.
An interesting feature of Achernar is its very rapid rotation around its axis, as a result of which it has an elongated shape.
10. Betelgeuse
Betelgeuse's maximum luminosity is 105,000 times that of the Sun, but it is about 640 light-years from the solar system, so it is not as bright as the previous nine stars. 
Because Betelgeuse's brightness gradually decreases from the center to the surface, scientists still cannot calculate its diameter.
Imagining the starry sky, probably everyone has in their head the thought of thousands of stars of the same type, shining on the boundless dark canvas of our planet. Not at all, in industrial cities, due to pollution, it is difficult to see that the flickering luminaries seriously differ not only in size, distance from the Earth, but also in power. If you want to see this difference, we recommend watching the amazing spectacle in nature, in an open area far from the city. We'll tell you where you need to look to see them, and finally answer the question - " Which star is the brightest in the sky?".
10 brightest stars in the sky
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Each star has its own history, life cycle and stages of formation. They differ in color and strength. For example, some of them are capable of igniting a nuclear fusion reaction. Amazing, isn't it? And one of the most powerful, unusual and brightest is the star Achernar, located 139 light years from our world. We are talking about a blue star whose brightness is 3000 times greater than the sun. Features fast rotation and high temperature. Due to the speed of movement, its equatorial radius is approximately 56% larger than the polar one.
A red star called Betelgeuse shines even brighter and more powerfully. It is the hottest in its class. Experts suggest that this will not last long, because sooner or later the hydrogen will run out and Betelgeuse will switch to helium. It is worth noting that the temperature is not too high, only 3500K, but it shines about 100,000 times brighter than the Sun. It is located approximately 600 light years from Earth. Over the next million years, the star is expected to go supernova, and will likely become its brightest. Perhaps our descendants will be able to see it even during the day.
The next brightest star is the F-class celestial body called Procyon. A rather modest star in its parameters, which today is on the verge of exhausting its hydrogen reserves. In terms of its dimensions, it is only 40% larger than the Sun, however, in terms of evolution, the subgiant shines 7 times more intensely and brightly. Why did Procyon receive such a high place in the ranking, since there are more powerful luminaries? The fact is that it is brighter than the Sun, taking into account 11.5 light years from us. This must be taken into account; if it were closer, we would have to pay more attention to creating lenses in sunglasses.
One of the brightest stars on the planet, the power of which can only be fully appreciated from Orion. An even more distant star, located 860 years from the planet. In this case, the core temperature is 12,000 degrees. It must be said that Rigel is not one of the main sequence stars. However, the blue giant is 120 thousand times brighter than the sun. To give you an idea, if a star were as distant from our planet as Mercury, we would not be able to see anything. However, even in the territory of Orion it blinds.
Speaking of unusual stars, Capella is the undisputed leader. What is so unique about the heavenly body? The fact is that this star consists of two surfaces at once, the temperature of each of which is greater than the sun. At the same time, supergiants are 78 times brighter. They are located 42 light years away. The combination of two stars is quite easy to detect on a clear day, or rather night. However, only knowledgeable people will be able to understand what this miracle in the sky looks like. You probably already understand what names are used to describe many terms in the Russian language, and not only that.
For many people, Vega is associated with an Internet provider, and for film fans, it is the home of aliens (the film “Contact”). In fact, Vega is a bright star located 25 light years from Earth. Its age is 500 million years. Today, astronomers use it as a zero star, that is, zero magnitude. Among all Class A luminaries, it is considered the most powerful. At the same time, it is about 40 times brighter than the sun. In our sky it is the fifth brightest, and in the northern part of the hemisphere it is second in this parameter to only one unique luminary, which will be discussed further.
The only orange star in this rating, on the evolutionary scale located between Capella and Procyon. The brightest star in the northern hemisphere of the planet. If you want to have an idea of its placement, focus on the handle of the Big Dipper bucket. It is always within a given constellation. About 170 times brighter than the sun. As part of its further development, it should become much stronger. It is located approximately 37 light years away.
We are talking about a triple system, each member of which is similar in its parameters to the sun. It's funny, but all the members of the Alpha Centauri system are much dimmer, any of the stars presented in the ranking are the brightest. However, the system is close enough to Earth that its illumination is noticeable even in the city. The distance is 4.4 light years. Well, it's time to talk about the most unique celestial bodies of this top. Surely, many are now aware of the choice of astrologers, who spend their time studying truly intangible objects for years on end.
This week they will take part in a project to count the stars in the constellation Orion, reports the Daily Telegraph. The campaign, organized by the Campaign to Protect Rural England (CPRE) and the British Astronomical Association's Campaign for Dark Skies (CfDS), aims to measure light pollution that interferes with vision stars from Earth.
A similar study conducted 4 years ago showed that 4/5 of the population (83%) does not see the starry sky at all, as it is obscured by light from the Earth. In 2007, almost 2 thousand people took part in the event and only 2% of them were able to see more than 30 stars in the sky. More than half of the people who took part in the study saw fewer than 10 stars.
The organizers of the action say that not only astronomers, but also ordinary residents suffer from this state of affairs, since excess light affects night sleep and disrupts the way of life accepted in the village. They are calling on local authorities to reduce street lighting at night, which should help improve the environmental situation and also save money from local budgets.
As “Around the World” reported, astronomers from Russia also complain about light pollution. In 2007, they called on First Deputy Prime Minister Dmitry Medvedev to “adopt a law or government resolution on the issue of light pollution in our cities,” arguing that such laws exist in many European countries. In particular, these laws do not allow floodlights to be shined into the sky and require that the light be directed only at specific objects.
There is also a medical side to the problem: American physician Richard Stevens from the University of Connecticut Health Center in Farmington, USA, and researchers from the Oncology Research Institute. N.N. Petrova in St. Petersburg came to the conclusion that increasing the level of night lighting and working night shifts lead to inhibition of melatonin synthesis. This is a hormone that prevents the formation and development of malignant tumors.
Interestingly, the most illuminated city on the planet is Las Vegas, USA. At nightfall, 24,000 neon electric lines light up every day over its 80-mile-square area. It is followed in terms of illumination by New York, Paris, Tokyo and Mexico City. According to our cosmonauts, Moscow is not much inferior to the largest metropolises in the world. But its luminous transport arteries are lost in the vast expanses of Russia, while in the USA, for example, they are clearly visible and cover the entire territory of the country like blood vessels.
