In fact, this question is not as simple as it seems. Determining the exact sizes of stars is very difficult; this is calculated based on a lot of indirect data, because we cannot see their disks directly. Direct observation of the stellar disk has so far been carried out only for some large and nearby supergiants, and there are millions of stars in the sky. Therefore, determine which is the most big star in the Universe, it is not so simple - you have to rely mainly on calculated data.
In addition, for some stars the boundary between the surface and the huge atmosphere is very blurred, and it is difficult to understand where one ends and the other begins. But this is an error not of some hundreds, but of millions of kilometers.
Many stars do not have a strictly defined diameter; they pulsate and become larger and smaller. And they can change their diameter very significantly.
In addition, science does not stand still. More and more accurate measurements are being made, distances and other parameters are being clarified, and some stars suddenly turn out to be much more interesting than they seemed. This also applies to sizes. Therefore, we will consider several candidates that are among the largest stars in the Universe. Note that all of them are located not so far by cosmic standards, and they are also the most big stars in the Galaxy.
A red hypergiant that claims to be the largest star in the Universe. Alas, this is not true, but it is very close. In size it is in third place.
VV Cephei - that is, double, and the giant in this system is component A, which will be discussed. The second component is an unremarkable blue star, 8 times bigger than the sun. But the red hypergiant is also a pulsating star, with a period of 150 days. Its size can vary from 1050 to 1900 times the diameter of the Sun, and at its maximum it shines 575,000 times brighter than our star!
This star is located 5000 light years away from us, and at the same time it has a brightness of 5.18 m in the sky, that is, with a clear sky and good vision, it can be found, and even easily with binoculars.
UY Shield
This red hypergiant is also striking in its size. Some sites mention it as the largest star in the Universe. Refers to semi-regular variables and pulsates, so the diameter can vary - from 1708 to 1900 solar diameters. Just imagine a star 1900 times larger than our Sun! If you place it in the center solar system, then all the planets, up to Jupiter, will be inside it.
Sun, Sirius, Pollux, Arcturus, against the background of UY Scutum. It is probably the largest star in the Universe.
In numbers, the diameter of this one of the largest stars in space is 2.4 billion kilometers, or 15.9 astronomical units. 5 billion suns could fit inside it. It shines 340,000 times stronger than the Sun, although the surface temperature is much lower - due to its larger area.
At its peak brightness, UY Scuti is visible as a faint reddish star with a brightness of 11.2 m, that is, it can be seen with a small telescope, but is not visible to the naked eye. The fact is that the distance to this large star is 9500 light years - we would not have seen another one at all. In addition, there are clouds of dust between us - if they were not there, UY Scuti would be one of the brightest stars in our sky, despite the enormous distance to it.
UY Scuti is a huge star. It can be compared with the previous candidate - VV Cepheus. At maximum they are approximately the same, and it is not even clear which one is larger. However, there is definitely an even bigger star!
VY Canis Majoris
The diameter of VY, however, according to some data, is estimated at 1800-2100 solar, that is, it is a clear record holder among all other red hypergiants. If it were in the center of the solar system, it would swallow all the planets, along with Saturn. The previous candidates for the title of the largest stars in the Universe would also fit completely into it.
It only takes 14.5 seconds for light to circle our Sun completely. To go around VY Canis Major, the light would have to fly 8.5 hours! If you decided to fly around the surface in a fighter jet at a speed of 4500 km/h, such a non-stop journey would take 220 years.
Comparison of the sizes of the Sun and VY Canis Majoris.
This star still raises a lot of questions, since its exact size is difficult to establish due to the blurry corona, which has a much lower density than the solar one. And the star itself has a density thousands of times less than the density of the air we breathe.
In addition, VY Canis Majoris is losing its matter and has formed a noticeable nebula around itself. This nebula may now contain even more matter than the star itself. In addition, it is unstable, and in the next 100 thousand years it will explode as a hypernova. Fortunately, it is 3900 light years away, and this terrible explosion does not threaten the Earth.
This star can be found in the sky with binoculars or a small telescope - its brightness varies from 6.5 to 9.6 m.
Which star is the largest in the Universe?
We looked at several of the largest stars in the Universe known to scientists today. Their sizes are amazing. All of them are candidates for this title, but the data is constantly changing - science does not stand still. According to some data, UY Scuti can also “swell” to 2200 solar diameters, that is, become even larger than VY Canis Majoris. On the other hand, there is too much disagreement about the size of VY Canis Majoris. So these two stars are almost equal candidates for the title of the largest stars in the Universe.
Which one will actually be larger will be shown further research and clarifications. While the majority is inclined in favor of UY Scuti, and you can safely call this star the largest in the Universe, it will be difficult to refute this statement.
Of course, it is not too correct to talk about the entire Universe. Perhaps this is the largest star in our galaxy Milky Way, known to scientists today. But since even larger ones have not yet been discovered, it is still the largest in the Universe.
Today you will learn about the most unusual stars. It is estimated that there are about 100 billion galaxies in the Universe and about 100 billion stars in each galaxy. With so many stars, there are bound to be some strange ones among them. Many of the sparkling, burning balls of gas are quite similar to each other, but some stand out for their strange size, weight and behavior. Using modern telescopes, scientists continue to study these stars to better understand them and the Universe, but mysteries still remain. Curious to know about the strangest stars? Here are the 25 most unusual stars in the Universe.
25. UY Scuti
Considered a supergiant star, UY Scuti is so large that it could engulf our star, half of our neighboring planets, and virtually our entire solar system. Its radius is approximately 1700 times the radius of the Sun.
24. Star of Methuselah
Photo: commons.wikimedia.org
The Star of Methuselah, also named HD 140283, truly lives up to its name. Some believe it is 16 billion years old, which is problematic because Big bang happened only 13.8 billion years ago. Astronomers have tried to use more advanced age methods to better date the star, but still believe it is at least 14 billion years old.
23. Torna-Zhitkov object
Photo: Wikipedia Commons.com
The existence of this object was originally proposed theoretically by Kip Thorne and Anna Zytkow; it consists of two stars, a neutron and a red supergiant, combined into one star. A potential candidate for this object has been named HV 2112.
22.R136a1 
Photo: flickr
Although UY Scuti is the biggest star, known to man, R136a1 is definitely one of the heaviest in the Universe. Its mass is 265 times greater than the mass of our Sun. What makes it strange is that we don't know exactly how it was formed. The main theory is that it was formed by the merger of several stars.
21.PSR B1257+12
Photo: en.wikipedia.org
Most of the exoplanets in the solar system PSR B1257+12 are dead and bathed in deadly radiation from their old star. Amazing fact about their star is a zombie star or pulsar that has died but the core still remains. The radiation emanating from it makes this solar system a no man's land.
20.SAO 206462
Photo: flickr
Consisting of two spiral arms spanning 14 million miles across, SAO 206462 is certainly a strange and unique star in the universe. While some galaxies are known to have arms, stars typically do not. Scientists believe that this star is in the process of creating planets.
19. 2MASS J0523-1403
Photo: Wikipedia Commons.com
2MASS J0523-1403 may be the smallest known star in the Universe, and it lies just 40 light-years away. Because it is small in size and mass, scientists believe it may be 12 trillion years old.
18. Heavy metal subdwarfs
Photo: ommons.wikimedia.org
Recently, astronomers discovered a pair of stars with a large number lead in the atmosphere, which creates thick and heavy clouds around the star. They're called HE 2359-2844 and HE 1256-2738, and they're located 800 and 1000 light-years away respectively, but you could just call them heavy metal subdwarfs. Scientists are still not sure how they form.
17. RX J1856.5-3754
Photo: Wikipedia Commons.com
From the moment they are born, neutron stars begin to continuously lose energy and cool down. It is therefore unusual that a 100,000-year-old neutron star such as RX J1856.5-3754 could be so hot and show no signs of activity. Scientists believe interstellar material is held tightly gravitational field star, resulting in enough energy to heat the star.
16. KIC 8462852
Photo: Wikipedia Commons.com
The star system KIC 8462852 has received intense attention and interest from SETI and astronomers for its unusual behavior recently. Sometimes it dims by 20 percent, which could mean something is orbiting around it. Of course, this led some to the conclusion that these were aliens, but another explanation is the debris of a comet that entered the same orbit with the star.
15. Vega
Photo: Wikipedia Commons.com
Vega is the fifth brightest star in the night sky, but that's not what makes it strange. Its high rotation speed of 960,600 km per hour gives it an egg shape, rather than a spherical shape like our Sun. There are also temperature variations, with colder temperatures at the equator.
14. SGR 0418+5729
Photo: commons.wikimedia.org
A magnet located 6,500 light-years from Earth, SGR 0418+5729 has the strongest magnetic field in the Universe. The strange thing about it is that it does not correspond to the image of traditional magnetars with a surface magnetic field, like ordinary neutron stars.
13. Kepler-47
Photo: Wikipedia Commons.com
In the constellation Cygnus, 4,900 light-years from Earth, astronomers have discovered for the first time a pair of planets orbiting two stars. Known as the Kelper-47 system, the orbiting stars eclipse each other every 7.5 days. One star is roughly the size of our Sun, but only 84 percent as bright. The discovery proves that there may be more than one planet in the stressed orbit of a binary star system.
12. La Superba
Photo: commons.wikimedia.org
La Superba is another massive star located 800 light years away. It is about 3 times heavier than our Sun and the size of four astronomical units. It is so bright that it can be observed from Earth with the naked eye.
11. MY Camelopardalis
Photo: commons.wikimedia.org
MY Camelopardalis was thought to be a single bright star, but it was later discovered that the two stars are so close that they practically touch each other. Two stars slowly join together to form one star. Nobody knows when they will completely merge.
10.PSR J1719-1438b
Photo: Wikipedia Commons.com
Technically, PSR J1719-1438b is not a star, but it once was. While it was still a star, its outer layers were sucked out by another star, turning it into a small planet. What's even more surprising about this former star, what is now a giant diamond planet, five times the size of Earth.
9. OGLE TR-122b
Photo: Photo: commons.wikimedia.org
The average star usually makes the other planets look like pebbles, but OGLE TR-122b is about the same size as Jupiter. That's right, this is the smallest star in the Universe. Scientists believe it originated as a stellar dwarf several billion years ago, marking the first time a star the size of a planet has been discovered.
8. L1448 IRS3B
Photo: commons.wikimedia.org
Astronomers discovered the three-star system L1448 IRS3B as it began to form. Using the ALMA telescope in Chile, they observed two young stars orbiting a much older star. They believe that these two young stars were the result of nuclear reaction with gas rotating around the star.
Photo: Wikipedia Commons.com
Mira, also known as Omicron Ceti, is 420 light-years away and is quite strange due to its constantly fluctuating brightness. Scientists consider it a dying star located on recent years of your life. Even more amazingly, it moves through space at a speed of 130 km per second and has a tail that stretches several light years.
6. Fomalhaut-C
Photo: Wikipedia Commons.com
If you thought the two-star system was cool, then you might want to see the Fomalhaut-C. This is a three-star system just 25 light-years from Earth. While triple star systems are not entirely unique, this one is because the location of the stars far away rather than close to each other is an anomaly. The star Fomalhaut-C is particularly far away from A and B.
5. Swift J1644+57
Photo: Wikipedia Commons.com
The black hole's appetite is indiscriminate. In the case of Swift J1644+57, a dormant black hole woke up and devoured the star. Scientists made this discovery in 2011 using X-ray and radio waves. It took 3.9 billion light years for the light to reach Earth.
4.PSR J1841-0500
Photo: Wikipedia Commons.com
Known for their regular and constantly pulsating glow, they are rapidly rotating stars that rarely turn off. But PSR J1841-0500 surprised scientific topics that he did this for only 580 days. Scientists believe that studying this star will help them understand how pulsars work.
3.PSR J1748-2446
Photo: Wikipedia Commons.com
The strangest thing about PSR J1748-2446 is that it is the fastest spinning object in the Universe. It has a density 50 trillion times that of lead. To top it all off, its magnetic field is a trillion times stronger than that of our Sun. In short, this is an insanely overactive star.
2. SDSS J090745.0+024507
Photo: Wikipedia Commons.com
SDSS J090745.0+024507 is a ridiculously long name for a runaway star. With the help of a supermassive black hole, the star has been knocked out of its orbit and is moving fast enough to escape the Milky Way. Let's hope that none of these stars rush towards us.
1. Magnetar SGR 1806-20
Photo: Wikipedia Commons.com
Magnetar SGR 1806-20 is a terrifying force that exists in our Universe. Astronomers detected a bright flash 50,000 light-years away that was so powerful it bounced off the Moon and illuminated Earth's atmosphere for ten seconds. A solar flare caused scientists questions about whether something like this could lead to the extinction of all life on Earth.
>> The largest star in the Universe
UY Scuti is the largest star in the Universe: description and characteristics of the star with photo, location in the constellation, distance from Earth, list of the most big stars.
It's easy to feel tiny when looking at the night sky. You just need to select an object for comparison. How about a star? Just look into the territory of the Scutum constellation and you will find the largest star in our galaxy and visible Universe - UY Scutum.
In 1860, the star was found by German scientists at the Bonn Observatory. But only in 2012 was it possible to conduct a review in Very Large Telescope(Atacama Desert). Since its discovery, it has become the largest star in size, surpassing Betelgeuse, VY Canis Majoris and NML Cygnus.
Of course, there are record holders for brightness and density, but UY Scuti has the largest overall size, with a radius of 1,054,378,000 - 1,321,450,000 miles, which is 1,700 times the Sun.
People think that the Earth is huge. But let's take an 8-inch ball. Then, in terms of scale, the Sun will be 73 feet in diameter, which is greater than the height of the White House. Now let's put UY Shield next to it and get a diameter of 125,000 feet.
What happens if you put UY Scutum in the solar position? The star will dine on the first five planets and leave the orbital path of Jupiter. But many people think that it is even capable of crossing the orbit of Saturn.
Well, let’s be glad that the star is still not located in the Solar System and is 9500 light years away.
It is important to emphasize that with the improvement of terrestrial instruments, we are discovering new objects that are distant over long distances. This means that one day we may come across an even bigger star.
It is worth noting that the largest known stars are represented here, since many objects remain outside the field of view. Also, some of these are variables, which means they are constantly compressing and expanding. Now you know what the biggest star in space is. Let's look at the rest of the ten biggest stars in the universe:
List of the largest stars in the Universe
The radius of the red supergiant VY Canis Majoris reaches 1800-2100 solar, making it the largest in the galaxy. If placed in place, it would cover the orbital path. Located 3900 light years away in the constellation Canis Major.
It is a red supergiant, 1000 times the radius of the Sun. Located 6000 light years away. Presented binary system, Where main star accompanied by a small blue one.
Mu Cephei
Mu Cephei is a red supergiant whose radius is 1,650 times larger than the Sun's and 38,000 times brighter.
V 838 Monoceros is a red variable star located 20,000 light years away. It can reach the size of Mu Cephei or VV Cepheus A, but the large distance makes it difficult to determine accurately. The range covers 380-1970 solar radii.
A red supergiant that is 1540 times larger than the solar radius. Located in the constellation Dorado.
V354 Cephei
A red supergiant, 1520 times the solar radius. Located 9000 light years away in the constellation Cepheus.
KY Swan
1420 times larger than the solar radius, although some estimates put the figure at 2850 times. The star is located 5,000 light years away and has not yet been able to obtain a clear image.
KW Sagittarius
The red supergiant is 1,460 times larger in radius than the Sun. Located 7800 light years away.
RW Cepheus
A red supergiant with a radius of 1600 solar. From the position of the Sun, it could reach the orbital path of Jupiter.
A red supergiant whose radius is 1000 times greater than the Sun. This is the most popular star, as it is located quite close (640 light years) in . It can transform into a supernova at any moment.
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10th place - AH Scorpio
The tenth place of the largest stars in our Universe is occupied by the red supergiant, located in the constellation Scorpio. The equatorial radius of this star is 1287 - 1535 radii of our Sun. Located approximately 12,000 light years from Earth.
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9th place - KY Lebed
The ninth place is occupied by a star located in the constellation Cygnus at a distance of approximately 5 thousand light years from Earth. The equatorial radius of this star is 1420 solar radii. However, its mass exceeds the mass of the Sun by only 25 times. KY Cygni shines about a million times brighter than the Sun.
8
8th place - VV Cepheus A
VV Cephei - eclipsing double star type Algol in the constellation Cepheus, which is located at a distance of about 5000 light years from Earth. In the Milky Way Galaxy it is the second largest star (after VY Canis Majoris). The equatorial radius of this star is 1050 - 1900 solar radii.
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7th place - VY Canis Major
The largest star in our Galaxy. The radius of the star lies in the range 1300 - 1540 radii of the Sun. It would take light 8 hours to circle the star. Research has shown that the star is unstable. Astronomers predict that VY Canis Majoris will explode as a hypernova within the next 100 thousand years. Theoretically, a hypernova explosion would cause gamma-ray bursts that could damage the contents of a local part of the Universe, destroying any cellular life within a radius of several light years, however, the hypergiant is not close enough to Earth to pose a threat (about 4 thousand light years).
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6th place - VX Sagittarius
A giant pulsating variable star. Its volume, as well as its temperature, change periodically. According to astronomers, the equatorial radius of this star is equal to 1520 radii of the Sun. The star got its name from the name of the constellation in which it is located. The manifestations of the star due to its pulsation resemble the biorhythms of the human heart.
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5th place - Westerland 1-26
The fifth place is occupied by a red supergiant, the radius of this star lies in the range 1520 - 1540 solar radii. It is located 11,500 light years from Earth. If Westerland 1-26 were at the center of the solar system, its photosphere would encompass the orbit of Jupiter. For example, the typical depth of the photosphere for the Sun is 300 km.
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4th place - WOH G64
WOH G64 is a red supergiant star located in the constellation Doradus. Located in the neighboring galaxy Large Magellanic Cloud. The distance to the solar system is approximately 163,000 light years. The radius of the star lies in the range 1540 - 1730 solar radii. The star will end its existence and go supernova in a few thousand or tens of thousands of years.
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3rd place - RW Cepheus
Bronze goes to the star RW Cephei. The red supergiant is located 2,739 light-years away. The equatorial radius of this star is 1636 solar radii.
2
2nd place - NML Lebed
The second place of the largest stars in the Universe is occupied by the red hypergiant in the constellation Cygnus. The radius of the star is approximately equal to 1650 solar radii. The distance to it is estimated at about 5300 light years. Astronomers discovered substances such as water, carbon monoxide, hydrogen sulfide, and sulfur oxide in the star's composition.
1
1st place - UY Shield
The largest star in our Universe at the moment is a hypergiant in the constellation Scutum. Located at a distance of 9500 light years from the Sun. The equatorial radius of the star is 1708 radii of our Sun. The star's luminosity is approximately 120,000 times greater than the luminosity of the Sun in the visible part of the spectrum, and would be much brighter if there were not a large accumulation of gas and dust around the star.
One of the popular ways of presenting information today is to compile ratings - finding out the tallest person in the world, the longest river, the oldest tree, etc. There are such ratings in the world of astronomy - the science of stars.
From school lessons We know well that our Sun, which gives our planet heat and light, is very small on the scale of the Universe. Stars of this type are called yellow dwarfs, and among the countless millions of stars there are many much larger and more spectacular astronomical objects to be found.
"Stellar" life cycle
Before looking for the largest star, let's remember how stars live and what stages they go through in their development cycle.
As is known, stars are formed from giant clouds of interstellar dust and gas, which gradually become denser, increase in mass and, under the influence of their own gravity, compress more and more. The temperature inside the cluster gradually increases, and the diameter decreases.
The phase indicating that an astronomical object has become a full-fledged star lasts 7-8 billion years. Depending on the temperature, stars in this phase can be blue, yellow, red, etc. The color is determined by the mass of the star and the physical and chemical processes occurring in it. 
But any star eventually begins to cool down and at the same time expand in volume, turning into a “red giant”, with a diameter tens or even hundreds of times greater than the original star. At this time, the star can pulsate, either expanding or contracting in diameter.
This period lasts several hundred million years and ends with an explosion, after which the remnants of the star collapse, forming a dim “white dwarf”, neutron star or “black hole”.
So, if we are looking for the largest star in the Universe, then it will most likely be a “red giant” - a star in the aging phase.
Biggest star
Today, astronomers know quite a lot of “red giants,” which can be called the largest stars in the observable part of the Universe. Since this type of star is subject to pulsation, then different years The leaders in size were considered:
- KY Cygnus - the mass exceeds the mass of the Sun by 25 times, and the diameter is 1450 solar;
- VV Cepheus - with a diameter of about 1200 solar;
- VY Canis Majoris - considered the largest in our Galaxy, its diameter is about 1540 solar diameters;
— VX Sagittarius – the diameter at the maximum pulsation phase reaches 1520 solar;
— WOH G64 is a star from our closest neighboring galaxy, the diameter of which reaches, according to various estimates, 1500-1700 solar; 
— RW Cepheus – with a diameter of 1630 times the diameter of the Sun;
— NML Cygnus is a “red giant” with a circumference exceeding 1650 solar diameters;
- UV Scutum - today is considered the largest in the observable part of the Universe, with a diameter of about 1700 diameters of our Sun.
The heaviest star in the Universe
It is worth mentioning another champion star, which is designated by astronomers as R136a1 and is located in one of the galaxies of the Large Magellanic Cloud. Its diameter is not very impressive yet, but its mass is 256 times the mass of our Sun. This star violates one of the main astrophysical theories, which states that the existence of stars with a mass of more than 150 solar masses is impossible due to the instability of internal processes.
By the way, according to astronomical calculations, R136a1 lost a fifth of its mass - initially this figure was within 310 solar masses. It is believed that the giant was formed as a result of the merger of several ordinary stars, so it is not stable and can explode at any moment, turning into a Supernova.
Even today it is ten million times brighter than the Sun. If you move R136a1 into our galaxy, it will eclipse the Sun with the same brightness with which the Sun now eclipses the Moon.
The brightest stars in the sky
Of those stars that we can see with the naked eye in the sky, the blue giant Rigel (constellation Orion) and the red Deneb (constellation Cygnus) have. 
The third brightest is the red Betelgeuse, which together with Rigel makes up the famous Belt of Orion.
