The Milky Way Galaxy is very majestic and beautiful. This huge world is our Motherland, our Solar system. All the stars and other objects that are visible to the naked eye in the night sky are our galaxy. Although there are some objects that are located in the Andromeda Nebula, a neighbor of our Milky Way.
Description of the Milky Way
The Milky Way Galaxy is huge, 100 thousand light years in size, and, as you know, one light year is equal to 9460730472580 km. Our solar system is located 27,000 light years from the center of the galaxy, in one of the arms called the Orion arm.
Our solar system orbits the center of the Milky Way galaxy. This happens in the same way as the Earth rotates around the Sun. The solar system completes a revolution every 200 million years.
Deformation
The Milky Way Galaxy appears as a disk with a bulge in the center. It's not the perfect shape. On one side there is a bend north of the center of the galaxy, and on the other it goes down, then turns to the right. Outwardly, this deformation somewhat resembles a wave. The disk itself is deformed. This is due to the presence of the Small and Large Magellanic Clouds nearby. They rotate around the Milky Way very quickly - this was confirmed by the Hubble telescope. These two dwarf galaxies are often called satellites of the Milky Way. The clouds create a gravitationally bound system that is very heavy and quite massive due to the heavy elements in the mass. It is assumed that they are like a tug of war between galaxies, creating vibrations. As a result, the Milky Way galaxy is deformed. The structure of our galaxy is special; it has a halo.
Scientists believe that in billions of years the Milky Way will absorb the Magellanic Clouds, and after some time it will be absorbed by Andromeda.
Halo
Wondering what kind of galaxy the Milky Way is, scientists began to study it. They managed to find out that 90% of its mass consists of dark matter, which is why a mysterious halo appears. Everything that is visible to the naked eye from Earth, namely that luminous matter, is approximately 10% of the galaxy.
Numerous studies have confirmed that the Milky Way has a halo. Scientists have compiled various models that take into account the invisible part and without it. After experiments, it was suggested that if there were no halo, then the speed of movement of the planets and other elements of the Milky Way would be less than now. Because of this feature, it was assumed that most of the components consist of invisible mass or dark matter.
Number of stars
The Milky Way galaxy is considered one of the most unique. The structure of our galaxy is unusual; there are more than 400 billion stars in it. About a quarter of them are large stars. Note: other galaxies have fewer stars. There are about ten billion stars in the Cloud, some others consist of a billion, and in the Milky Way there are more than 400 billion different stars, and only a small part is visible from Earth, about 3000. It is impossible to say exactly how many stars are contained in the Milky Way, so how the galaxy is constantly losing objects due to them going supernova.
Gases and dust
Approximately 15% of the galaxy is dust and gases. Maybe because of them our galaxy is called the Milky Way? Despite its enormous size, we can see about 6,000 light years ahead, but the size of the galaxy is 120,000 light years. It may be larger, but even the most powerful telescopes cannot see beyond that. This is due to the accumulation of gas and dust.
The thickness of the dust does not allow visible light to pass through, but infrared light passes through, allowing scientists to create star maps.
What happened before
According to scientists, our galaxy has not always been like this. The Milky Way was created by the merger of several other galaxies. This giant captured other planets and areas, which had a strong impact on the size and shape. Even now, planets are being captured by the Milky Way galaxy. An example of this is the objects of Canis Major, a dwarf galaxy located near our Milky Way. Canis stars are periodically added to our universe, and from ours they move to other galaxies, for example, objects are exchanged with the Sagittarius galaxy.
View of the Milky Way
Not a single scientist or astronomer can say exactly what our Milky Way looks like from above. This is due to the fact that Earth is located in the Milky Way galaxy, 26,000 light years from the center. Because of this location, it is not possible to take pictures of the entire Milky Way. Therefore, any image of a galaxy is either pictures of other visible galaxies or someone’s imagination. And we can only guess what she really looks like. There is even a possibility that we now know as much about it as the ancient people who believed the Earth to be flat.
Center
The center of the Milky Way galaxy is called Sagittarius A* - a great source of radio waves, suggesting that there is a huge black hole at its very heart. According to assumptions, its size is a little more than 22 million kilometers, and this is the hole itself.
All the substances that try to get into the hole form a huge disk, almost 5 million times larger than our Sun. But even this retraction force does not prevent new stars from forming at the edge of the black hole.
Age
Based on estimates of the composition of the Milky Way galaxy, it was possible to establish an estimated age of about 14 billion years. The oldest star is just over 13 billion years old. The age of a galaxy is calculated by determining the age of the oldest star and the phases preceding its formation. Based on the available data, scientists have suggested that our universe is about 13.6-13.8 billion years old.
First, the bulge of the Milky Way was formed, then its middle part, in the place of which a black hole subsequently formed. Three billion years later, a disk with sleeves appeared. Gradually it changed, and only about ten billion years ago it began to look the way it does now.
We are part of something bigger
All the stars in the Milky Way galaxy are part of a larger galactic structure. We are part of the Virgo Supercluster. The closest galaxies to the Milky Way, such as the Magellanic Cloud, Andromeda and other fifty galaxies, are one cluster, the Virgo Supercluster. A supercluster is a group of galaxies that occupies a huge area. And this is only a small part of the stellar surroundings.
The Virgo Supercluster contains more than a hundred groups of clusters over an area more than 110 million light-years in diameter. The Virgo cluster itself is a small part of the Laniakea supercluster, and it, in turn, is part of the Pisces-Cetus complex.
Rotation
Our Earth moves around the Sun, making a full revolution in 1 year. Our Sun orbits in the Milky Way around the center of the galaxy. Our galaxy moves in relation to a special radiation. CMB radiation is a convenient reference point that allows us to determine the speed of a wide variety of matters in the Universe. Studies have shown that our galaxy rotates at a speed of 600 kilometers per second.
Appearance of the name
The galaxy got its name because of its special appearance, reminiscent of spilled milk in the night sky. The name was given to it back in Ancient Rome. Back then it was called the “milk road.” To this day it is called the Milky Way, associating the name with the appearance of a white stripe in the night sky, with spilled milk.
References to the galaxy have been found since the era of Aristotle, who said that the Milky Way is the place where the celestial spheres contact the terrestrial ones. Until the telescope was created, no one added anything to this opinion. And only from the seventeenth century people began to look at the world differently.
Our neighbours
For some reason, many people think that the closest galaxy to the Milky Way is Andromeda. But this opinion is not entirely correct. Our closest “neighbor” is the Canis Major galaxy, located inside the Milky Way. It is located at a distance of 25,000 light years from us, and 42,000 light years from the center. In fact, we are closer to Canis Major than to the black hole at the center of the galaxy.
Before the discovery of Canis Major at a distance of 70 thousand light years, Sagittarius was considered the closest neighbor, and after that the Large Magellanic Cloud. Unusual stars with enormous class M densities were discovered in Canis.
According to the theory, the Milky Way swallowed Canis Major along with all its stars, planets and other objects.
Collision of galaxies
Recently, information has become increasingly common that the closest galaxy to the Milky Way, the Andromeda Nebula, will swallow our universe. These two giants formed at about the same time - about 13.6 billion years ago. It is believed that these giants are capable of uniting galaxies, but due to the expansion of the Universe they should move away from each other. But, contrary to all the rules, these objects are moving towards each other. The speed of movement is 200 kilometers per second. It is estimated that in 2-3 billion years Andromeda will collide with the Milky Way.
Astronomer J. Dubinsky created a model of the collision shown in this video:
The collision will not lead to a catastrophe on a global scale. And after several billion years, a new system will be formed, with the usual galactic forms.
Lost galaxies
Scientists conducted a large-scale study of the starry sky, covering approximately an eighth of it. As a result of an analysis of the star systems of the Milky Way galaxy, it was possible to find out that there are previously unknown streams of stars on the outskirts of our universe. This is all that remains of small galaxies that were once destroyed by gravity.
The telescope installed in Chile took a huge number of images that allowed scientists to assess the sky. The images estimate that our galaxy is surrounded by a halo of dark matter, thin gas and few stars, remnants of dwarf galaxies that were once swallowed up by the Milky Way. Having a sufficient amount of data, scientists were able to assemble a “skeleton” of dead galaxies. It’s like in paleontology - it’s difficult to say from a few bones what a creature looked like, but with enough data, you can assemble a skeleton and guess what the lizard was like. So it is here: the information content of the images made it possible to recreate eleven galaxies that were swallowed up by the Milky Way.
Scientists are confident that as they observe and evaluate the information they receive, they will be able to find several more new disintegrated galaxies that were “eaten” by the Milky Way.
We're under fire
According to scientists, the hypervelocity stars located in our galaxy did not originate in it, but in the Large Magellanic Cloud. Theorists cannot explain many aspects regarding the existence of such stars. For example, it is impossible to say exactly why a large number of hypervelocity stars are concentrated in Sextant and Leo. Having revised the theory, scientists came to the conclusion that such a speed can only develop due to the influence of a black hole located in the center of the Milky Way.
Recently, more and more stars have been discovered that do not move from the center of our galaxy. After analyzing the trajectory of ultra-fast stars, scientists were able to find out that we are under attack from the Large Magellanic Cloud.
Death of the planet
By observing the planets in our galaxy, scientists were able to see how the planet died. She was consumed by the aging star. During the expansion and transformation into a red giant, the star absorbed its planet. And another planet in the same system changed its orbit. Having seen this and assessed the state of our Sun, scientists came to the conclusion that the same thing would happen to our luminary. In about five million years it will become a red giant.
How the galaxy works
Our Milky Way has several arms that rotate in a spiral. The center of the entire disk is a gigantic black hole.
We can see the galactic arms in the night sky. They look like white stripes, reminiscent of a milk road that is strewn with stars. These are the branches of the Milky Way. They are best seen in clear weather in the warm season, when there is the most cosmic dust and gases.
The following arms are distinguished in our galaxy:
- Angle branch.
- Orion. Our solar system is located in this arm. This sleeve is our “room” in the “house”.
- Carina-Sagittarius sleeve.
- Perseus branch.
- Branch of the Shield of the Southern Cross.
It also contains a core, a gas ring, and dark matter. It supplies about 90% of the entire galaxy, and the remaining ten are visible objects.
Our Solar System, the Earth and other planets are a single whole of a huge gravitational system that can be seen every night in a clear sky. In our “home” a variety of processes are constantly taking place: stars are born, they decay, we are bombarded by other galaxies, dust and gases appear, stars change and go out, others flare up, they dance around... And all this happens somewhere out there, far away in a universe about which we know so little. Who knows, maybe the time will come when people will be able to reach other branches and planets of our galaxy in a matter of minutes, and travel to other universes.
The Milky Way is our home galaxy, in which the solar system is located, in which the planet Earth is located, on which people live. It belongs to the barred spiral galaxies and is included in the Local Group of galaxies along with the Andromeda Galaxy, the Triangulum Galaxy and 40 dwarf galaxies. The diameter of the Milky Way is 100,000 light years. There are about 200-400 billion stars in our galaxy. Our solar system is located on the outskirts of the galactic disk, in a relatively calm place that allowed life to arise on our planet. Perhaps we are not the only ones living in the Milky Way, but this remains to be seen. Although, in the ocean of the Universe, the entire history of mankind is nothing more than a barely noticeable ripple, it is very interesting for us to explore the Milky Way and follow the developments of events in our native galaxy.
According to astronomers, most stars slowly rotate around galactic centers at a speed of no more than 100 kilometers per second. However, there are exceptions to this rule. Over the past few decades, scientists have discovered about 20 hypervelocity stars in our galaxy. The latest such discovery is object PSR J0002+6216. its movement is 1130 kilometers per second or more than four million kilometers per hour. It is quite enough to get to the same Moon in 6 minutes. According to astronomers from the American National Radio Astronomy Observatory, who discovered it, if such dynamics continue, in the distant future the object will escape from our galaxy.
On a clear, moonless night, a pale, faintly shining ribbon spreads across the entire sky in a bright arc - Milky Way like a ring encircling the entire sky. Looking at it through a telescope, you are convinced that it is a huge collection of very faint stars.
Since the Milky Way encircles the entire sky, dividing it almost in half, then, obviously, our solar system is located near this plane, near the galactic plane, as it is called.
The farther from the plane of the Milky Way, the fewer faint stars there are and the smaller the distance in these directions the star system stretches. In general, our star system, called Galaxy, occupies a space that resembles a lens from the outside. It is flattened - thickest in the middle and thinner towards the edges. If we could see it “from above” or “from below”, it would have, roughly speaking, the appearance of a circle (not a ring). From the “side” it would look like a spindle. But what are the dimensions of this “spindle”? Is the arrangement of stars in it uniform?
This has become clear in recent years, although the answer to this question is given by a simple examination of the Milky Way, which all consists of a heap of star clouds. Some clouds are brighter and have more stars (such as in the constellations Sagittarius and Cygnus), while others are poorer in stars. The solar system is also located in one of them, called local system.
The Milky Way - how we can see it from Earth
The most powerful clouds of stars are in the direction of the constellation Sagittarius - this is where the core of the galaxy is located, which is where the Milky Way is brightest. Considering that we see the constellation Sagittarius “from the side,” it is logical to conclude that our solar system is far from being in the center of the Milky Way Galaxy, but rather is shifted closer to its edge.
Considering that the diameter of our Galaxy is almost 100 thousand light years, the solar system is located 25 thousand light years from its center, that is, about half its radius.
The solar system revolves around the center of the Galaxy, which lies at a distance of 25 thousand light years from us in the direction of the constellation Sagittarius, at a speed of 250 km/sec. The shape of its orbit is still unknown, but if it is close to a circle, which is likely, then the Sun completes one revolution along it in 200 million years. This period, if you like, can be taken as a “cosmic year” for measuring very large periods of time.
The entire history of mankind in comparison with such a period is only a short moment! If we could see the Sun rushing and turning in its orbit, as we see a train turning at a curve in the track, then we could not follow the revolutions of the planets around the Sun: they would seem to be spinning faster than an electric fan.
When rotating around the center of the Galaxy, not all stars move exactly the same way, and, for example, short-period ones lag behind the Sun by 100 kilometers every second.
The movement of our solar system at a speed of 20 km/sec in the direction of our “neighbor” constellation Lyra is movement within our star cloud, or local system. It is small and does not prevent us, together with the entire local system, from circling around the galactic center.
How bright the center of our Galaxy - the clouds of stars of the Milky Way in the constellation Sagittarius - should have seemed, if they had not been concealed, eclipsed by the absorption of light in the masses filling the space between us and this center!
The mass of our Galaxy, now estimated in various ways, is equal to two hundred billion solar masses, with one thousandth of it contained in interstellar gas and dust. The mass is almost the same, and the mass of the Triangulum galaxy is estimated to be twenty times less.
Looking at the Milky Way and other galaxies from the side, it seems that the stars are so close in it that they literally rub their sides against each other. In reality, everything is completely different.
If we built a model of the Milky Way in which the stars were represented as raindrops, then to give a correct idea of the distribution of stars within a typical galaxy, the mutual distances of the drops would have to be approximately 65 km!
Consequently, for every cubic centimeter of stellar matter there are over 10,000,000,000,000,000,000,000,000 cubic centimeters.
It’s a paradox, but for studying the structure of the Milky Way Galaxy we are at a very disadvantage. We live in it and see it from the inside. It's like trying to imagine the outside of your home while you're in your apartment and looking out the window.
But if our home is the Galaxy, then other houses are other galaxies. Therefore, we can guess about the appearance of our house by studying other houses that we see from the window.
Observing the Milky Way in the sky.
However, no one prevents us from looking at what is visible directly “from the window” in the sky. So what will an observer from Earth see?
The Milky Way passes through the constellations Swan, Cassiopeia And Perseus. The Milky Way is almost invisible. It stretches along the northern side of the sky in a small and low arc from the northwest (where Perseus stands) to the northeast (where Swan stands). The highest point of this arc, at Cassiopeia, is located midway between the horizon and the horizon.
The cosmos that we are trying to study is a huge and endless space in which there are tens, hundreds, thousands of trillions of stars, united in certain groups. Our Earth does not live on its own. We are part of the solar system, which is a small particle and part of the Milky Way, a larger cosmic formation.
Our Earth, like the other planets of the Milky Way, our star called the Sun, like other stars of the Milky Way, move in the Universe in a certain order and occupy designated places. Let's try to understand in more detail what is the structure of the Milky Way, and what are the main features of our galaxy?
Origin of the Milky Way
Our galaxy has its own history, like other areas of outer space, and is the product of a catastrophe on a universal scale. The main theory of the origin of the Universe that dominates the scientific community today is the Big Bang. A model that perfectly characterizes the Big Bang theory is a nuclear chain reaction at the microscopic level. Initially, there was some kind of substance that, for certain reasons, instantly began to move and exploded. There is no need to talk about the conditions that led to the onset of the explosive reaction. This is far from our understanding. Now the Universe, formed 15 billion years ago as a result of a cataclysm, is a huge, endless polygon.
The primary products of the explosion initially consisted of accumulations and clouds of gas. Subsequently, under the influence of gravitational forces and other physical processes, the formation of larger objects on a universal scale occurred. Everything happened very quickly by cosmic standards, over billions of years. First there was the formation of stars, which formed clusters and later merged into galaxies, the exact number of which is unknown. In its composition, galactic matter is atoms of hydrogen and helium in the company of other elements, which are the building material for the formation of stars and other space objects.
It is not possible to say exactly where in the Universe the Milky Way is located, since the exact center of the universe is unknown.
Due to the similarity of the processes that formed the Universe, our galaxy is very similar in structure to many others. By its type, it is a typical spiral galaxy, a type of object that is widespread in the Universe. In terms of its size, the galaxy is in the golden mean - neither small nor huge. Our galaxy has many more smaller stellar neighbors than those of colossal size.
The age of all galaxies that exist in outer space is also the same. Our galaxy is almost the same age as the Universe and is 14.5 billion years old. Over this enormous period of time, the structure of the Milky Way has changed several times, and this is still happening today, only imperceptibly, in comparison with the pace of earthly life.
There is a curious story about the name of our galaxy. Scientists believe that the name Milky Way is legendary. This is an attempt to connect the location of the stars in our sky with the ancient Greek myth about the father of the gods Kronos, who devoured his own children. The last child, who faced the same sad fate, turned out to be thin and was given to a nurse to be fattened. During feeding, splashes of milk fell on the sky, thereby creating a milk trail. Subsequently, scientists and astronomers of all times and peoples agreed that our galaxy is indeed very similar to a milk road.
The Milky Way is currently in the middle of its development cycle. In other words, the cosmic gas and material to form new stars is running out. The existing stars are still quite young. As in the story with the Sun, which may turn into a Red Giant in 6-7 billion years, our descendants will observe the transformation of other stars and the entire galaxy as a whole into the red sequence.
Our galaxy may cease to exist as a result of another universal cataclysm. Research topics in recent years are focused on the upcoming meeting of the Milky Way with our closest neighbor, the Andromeda galaxy, in the distant future. It is likely that the Milky Way will break up into several small galaxies after meeting the Andromeda Galaxy. In any case, this will be the reason for the emergence of new stars and the reorganization of the space closest to us. We can only guess what the fate of the Universe and our galaxy will be in the distant future.
Astrophysical parameters of the Milky Way
In order to imagine what the Milky Way looks like on a cosmic scale, it is enough to look at the Universe itself and compare its individual parts. Our galaxy is part of a subgroup, which in turn is part of the Local Group, a larger formation. Here our cosmic metropolis neighbors the Andromeda and Triangulum galaxies. The trio is surrounded by more than 40 small galaxies. The local group is already part of an even larger formation and is part of the Virgo supercluster. Some argue that these are only rough guesses about where our galaxy is located. The scale of the formations is so enormous that it is almost impossible to imagine it all. Today we know the distance to the nearest neighboring galaxies. Other deep space objects are out of sight. Their existence is only theoretically and mathematically allowed.
The location of the galaxy became known only thanks to approximate calculations that determined the distance to its nearest neighbors. The Milky Way's satellites are dwarf galaxies - the Small and Large Magellanic Clouds. In total, according to scientists, there are up to 14 satellite galaxies that form the escort of the universal chariot called the Milky Way.
As for the visible world, today there is enough information about what our galaxy looks like. The existing model, and with it the map of the Milky Way, is compiled on the basis of mathematical calculations, data obtained as a result of astrophysical observations. Each cosmic body or fragment of the galaxy takes its place. This is just like in the Universe, only on a smaller scale. The astrophysical parameters of our cosmic metropolis are interesting, and they are impressive.
Our galaxy is a barred spiral galaxy, which is designated on star maps by the index SBbc. The diameter of the galactic disk of the Milky Way is about 50-90 thousand light years or 30 thousand parsecs. For comparison, the radius of the Andromeda galaxy is 110 thousand light years on the scale of the Universe. One can only imagine how much larger our neighbor is than the Milky Way. The sizes of the dwarf galaxies closest to the Milky Way are tens of times smaller than those of our galaxy. Magellanic clouds have a diameter of only 7-10 thousand light years. There are about 200-400 billion stars in this huge stellar cycle. These stars are collected in clusters and nebulae. A significant part of it is the arms of the Milky Way, in one of which our solar system is located.
Everything else is dark matter, clouds of cosmic gas and bubbles that fill interstellar space. The closer to the center of the galaxy, the more stars there are, the more crowded outer space becomes. Our Sun is located in a region of space consisting of smaller space objects located at a considerable distance from each other.
The mass of the Milky Way is 6x1042 kg, which is trillions of times more than the mass of our Sun. Almost all the stars inhabiting our stellar country are located in the plane of one disk, the thickness of which, according to various estimates, is 1000 light years. It is not possible to know the exact mass of our galaxy, since most of the visible spectrum of stars is hidden from us by the arms of the Milky Way. In addition, the mass of dark matter, which occupies vast interstellar spaces, is unknown.
The distance from the Sun to the center of our galaxy is 27 thousand light years. Being on the relative periphery, the Sun rapidly moves around the center of the galaxy, completing a full revolution every 240 million years.
The center of the galaxy has a diameter of 1000 parsecs and consists of a core with an interesting sequence. The center of the core has the shape of a bulge, in which the largest stars and a cluster of hot gases are concentrated. It is this region that releases a huge amount of energy, which in total is greater than that emitted by the billions of stars that make up the galaxy. This part of the core is the most active and brightest part of the galaxy. At the edges of the core there is a bridge, which is the beginning of the arms of our galaxy. Such a bridge arises as a result of the colossal gravitational force caused by the rapid speed of rotation of the galaxy itself.
Considering the central part of the galaxy, the following fact appears paradoxical. Scientists for a long time could not understand what is in the center of the Milky Way. It turns out that in the very center of a star country called the Milky Way there is a supermassive black hole, the diameter of which is about 140 km. It is there that most of the energy released by the galactic core goes; it is in this bottomless abyss that stars dissolve and die. The presence of a black hole at the center of the Milky Way indicates that all processes of formation in the Universe must end someday. Matter will turn into antimatter and everything will happen again. How this monster will behave in millions and billions of years, the black abyss is silent, which indicates that the processes of absorption of matter are only gaining strength.
The two main arms of the galaxy extend from the center - the Shield of the Centaur and the Shield of Perseus. These structural formations received their names from the constellations located in the sky. In addition to the main arms, the galaxy is surrounded by 5 more minor arms.
Near and distant future
The arms, born from the core of the Milky Way, unwind in a spiral, filling outer space with stars and cosmic material. An analogy with cosmic bodies that revolve around the Sun in our star system is appropriate here. A huge mass of stars, large and small, clusters and nebulae, cosmic objects of various sizes and natures, spins on a giant carousel. All of them create a wonderful picture of the starry sky, which people have been looking at for thousands of years. When studying our galaxy, you should know that the stars in the galaxy live according to their own laws, being today in one of the arms of the galaxy, tomorrow they will begin their journey in the other direction, leaving one arm and flying to another.
Earth in the Milky Way galaxy is far from the only planet suitable for life. This is just a particle of dust, the size of an atom, which is lost in the vast star world of our galaxy. There can be a huge number of such Earth-like planets in the galaxy. It is enough to imagine the number of stars that in one way or another have their own stellar planetary systems. Other life may be far away, at the very edge of the galaxy, tens of thousands of light years away, or, conversely, present in neighboring areas that are hidden from us by the arms of the Milky Way.
Astronomers say that with the naked eye a person can see about 4.5 thousand stars. And this despite the fact that only a small part of one of the most amazing and unidentified pictures of the world is revealed to our eyes: in the Milky Way Galaxy alone there are more than two hundred billion celestial bodies (scientists have the opportunity to observe only two billion).
The Milky Way is a barred spiral galaxy, representing a huge gravitationally bound star system in space. Together with the neighboring Andromeda and Triangulum galaxies and more than forty dwarf satellite galaxies, it is part of the Virgo Supercluster.
The age of the Milky Way exceeds 13 billion years, and during this time from 200 to 400 billion stars and constellations, more than a thousand huge gas clouds, clusters and nebulae have formed in it. If you look at a map of the Universe, you can see that the Milky Way is presented on it in the form of a disk with a diameter of 30 thousand parsecs (1 parsec is equal to 3.086 * 10 to the 13th power of kilometers) and an average thickness of about a thousand light years (in one light year almost 10 trillion kilometers).
Astronomers find it difficult to answer exactly how much the Galaxy weighs, since most of the weight is not contained in the constellations, as previously thought, but in dark matter, which does not emit or interact with electromagnetic radiation. According to very rough calculations, the weight of the Galaxy ranges from 5*10 11 to 3*10 12 solar masses.
Like all celestial bodies, the Milky Way rotates around its axis and moves around the Universe. It should be taken into account that when moving, galaxies constantly collide with each other in space and the one that has larger sizes absorbs smaller ones, but if their sizes coincide, active star formation begins after the collision.
Thus, astronomers suggest that in 4 billion years the Milky Way in the Universe will collide with the Andromeda Galaxy (they are approaching each other at a speed of 112 km/s), causing the emergence of new constellations in the Universe.
As for the movement around its axis, the Milky Way moves unevenly and even chaotically in space, since each star system, cloud or nebula located in it has its own speed and orbits of different types and shapes.
Galaxy structure
If you look closely at a map of space, you can see that the Milky Way is very compressed in the plane and looks like a “flying saucer” (the Solar system is located almost at the very edge of the star system). The Milky Way Galaxy consists of a core, a bar, a disk, spiral arms and a crown.
Core
The core is located in the constellation Sagittarius, where there is a source of non-thermal radiation, the temperature of which is about ten million degrees - a phenomenon characteristic only of the nuclei of galaxies. In the center of the core there is a condensation - a bulge, consisting of a large number of old stars moving in an elongated orbit, many of which are at the end of their life cycle.
So, some time ago, American astronomers discovered an area here measuring 12 by 12 parsecs, consisting of dead and dying constellations.
At the very center of the core there is a supermassive black hole (an area in outer space that has such powerful gravity that even light is unable to leave it), around which a smaller black hole rotates. Together they exert such a strong gravitational influence on nearby stars and constellations that they move along trajectories unusual for celestial bodies in the Universe.
Also, the center of the Milky Way is characterized by an extremely strong concentration of stars, the distance between which is several hundred times less than at the periphery. The speed of movement of most of them is absolutely independent of how far they are from the core, and therefore the average rotation speed ranges from 210 to 250 km/s.
Jumper
The bridge, 27 thousand light years in size, crosses the central part of the Galaxy at an angle of 44 degrees to the conventional line between the Sun and the core of the Milky Way. It consists mainly of old red stars (about 22 million), and is surrounded by a ring of gas that contains most of the molecular hydrogen, and is therefore the region where stars are formed in the greatest numbers. According to one theory, such active star formation occurs in the bridge due to the fact that it passes gas through itself, from which constellations are born.
Disk
The Milky Way is a disk consisting of constellations, gas nebulae and dust (its diameter is about 100 thousand light years with a thickness of several thousand). The disk rotates much faster than the corona, which is located at the edges of the Galaxy, while the rotation speed at different distances from the core is unequal and chaotic (varies from zero in the core to 250 km/h at a distance of 2 thousand light years from it). Gas clouds, as well as young stars and constellations, are concentrated near the plane of the disk.
On the outer side of the Milky Way there are layers of atomic hydrogen, which extend into space one and a half thousand light years from the outer spirals. Despite the fact that this hydrogen is ten times thicker than in the center of the Galaxy, its density is just as many times lower. On the outskirts of the Milky Way, dense accumulations of gas with a temperature of 10 thousand degrees, the dimensions of which exceed several thousand light years, were discovered.
Spiral sleeves
Immediately behind the gas ring there are five main spiral arms of the Galaxy, the size of which ranges from 3 to 4.5 thousand parsecs: Cygnus, Perseus, Orion, Sagittarius and Centauri (the Sun is located on the inner side of the Orion arm). Molecular gas is located unevenly in the arms and does not always obey the rules of rotation of the Galaxy, introducing errors.
Crown
The Milky Way's corona appears as a spherical halo that extends five to ten light years beyond the Galaxy. The corona consists of globular clusters, constellations, individual stars (mostly old and low-mass), dwarf galaxies, and hot gas. They all move around the core in elongated orbits, while the rotation of some stars is so random that even the speed of nearby stars can differ significantly, so the corona rotates extremely slowly.
According to one hypothesis, the corona arose as a result of the absorption of smaller galaxies by the Milky Way, and is therefore their remnants. According to preliminary data, the age of the halo exceeds twelve billion years and is the same age as the Milky Way, and therefore star formation here has already completed.
star space
If you look at the night starry sky, the Milky Way can be seen from absolutely anywhere on the globe in the form of a strip of lightish color (since our star system is located inside the Orion arm, only part of the Galaxy is accessible for viewing).
The map of the Milky Way shows that our Sun is located almost on the disk of the Galaxy, at its very edge, and its distance to the core is from 26-28 thousand light years. Considering that the Sun moves at a speed of about 240 km/h, to make one revolution, it needs to spend about 200 million years (over the entire period of its existence, our star has not flown around the Galaxy thirty times).
It is interesting that our planet is located in a corotation circle - a place where the speed of rotation of stars coincides with the speed of rotation of the arms, so stars never leave these arms or enter them. This circle is characterized by a high level of radiation, so it is believed that life can only arise on planets near which there are very few stars.
This fact also applies to our Earth. Being on the periphery, it is located in a fairly calm place in the Galaxy, and therefore for several billion years it was almost not subject to global cataclysms, for which the Universe is so rich. Perhaps this is one of the main reasons that life was able to originate and survive on our planet.