Our Galaxy - Milky Way

© Vladimir Kalanov
"Knowledge is power".

Looking at the night starry sky, you can see a dimly glowing whitish stripe that crosses the celestial sphere. This diffuse glow comes both from several hundred billion stars and from the scattering of light by tiny particles of dust and gas in interstellar space. This is our Milky Way galaxy. The Milky Way is a galaxy to which the solar system belongs with its planets, including the Earth. It is visible from anywhere on the earth's surface. The Milky Way forms a ring, so from any point on Earth we see only part of it. The Milky Way, which appears to be a dim road of light, is actually made up of a huge number of stars that are not individually visible to the naked eye. He was the first to think about this at the beginning of the 17th century when he pointed the telescope he had made at the Milky Way. What Galileo first saw took his breath away. In the place of the huge whitish strip of the Milky Way, sparkling clusters of countless stars, visible individually, opened up to his gaze. Today, scientists believe that the Milky Way contains a huge number of stars - about 200 billion.

Rice. 1 schematic representation of our Galaxy and the surrounding halo.

The Milky Way is a galaxy consisting of a large flat - main - disk-shaped body with a diameter exceeding a distance of 100 thousand light years. The disk of the Milky Way itself is “relatively thin” – several thousand light years thick. Most of the stars are located inside the disk. In terms of its morphology, the disk is not compact, has a complex structure; inside it there are uneven structures that extend from the core to the periphery of the Galaxy. These are the so-called “spiral arms” of our Galaxy, high-density zones where new stars form from clouds of interstellar dust and gas.

Rice. 2 Center of the Galaxy. Conditional tone image of the center of the Milky Way.

Explanation of the picture: The light source in the middle is Sagittarius A, an active star formation zone, located near the galactic core. The center is surrounded by a gaseous ring (pink circle). The outer ring contains molecular clouds (orange) and ionized hydrogen space in pink.

The galactic core is located in the central part of the Milky Way's disk. The core is made up of billions of old stars. The central part of the core itself is a very massive region with a diameter of only a few light years, inside of which, according to the latest astronomical research, there is a supermassive black hole, possibly even several black holes, with masses of about 3 million Suns.

Around the disk of the Galaxy there is a spherical halo (corona) containing dwarf galaxies (Large and Small Magellanic clouds, etc.), globular star clusters, individual stars, groups of stars and hot gas. Some of the individual groups of stars interact with globular clusters and dwarf galaxies. There is a hypothesis, arising from an analysis of the structure of the halo and the trajectories of motion of star clusters, that globular clusters, like the galactic corona itself, may be the remnants of former satellite galaxies absorbed by our Galaxy as a result of earlier interactions and collisions.

According to scientific assumptions, our Galaxy also contains dark matter, which is perhaps much more abundant than all visible matter in all observation ranges.

Dense regions of gas several thousand light years in size, with a temperature of 10,000 degrees and a mass of 10 million Suns have been discovered on the outskirts of the Galaxy.

Our Sun is almost on the disk, at a distance of about 28,000 light years from the center of the Galaxy. In other words, it is located on the periphery, at a distance of almost 2/3 of the galactic radius from the center, which is a distance of about 8 kiloparsecs from the center of our Galaxy.

Rice. 3 The plane of the Galaxy and the plane of the Solar System do not coincide, but are at an angle to each other.

Position of the Sun in the Galaxy

The position of the Sun in the Galaxy and its movement are also discussed in detail in the “Sun” section of our website (see). To complete a full revolution, the Sun takes about 250 million years (according to some sources 220 million years), which constitute a galactic year (the speed of the Sun is 220 km/s, that is, almost 800,000 km/h!). Every 33 million years, the Sun crosses the galactic equator, then rises above its plane to a height of 230 light years and descends again towards the equator. It takes, as already mentioned, about 250 million years for the Sun to complete a full revolution.

Since we are inside the Galaxy and looking at it from the inside, its disk appears visible on the celestial sphere as a strip of stars (this is the Milky Way), and therefore it is difficult to determine the real three-dimensional spatial structure of the Milky Way from Earth.

Rice. 4 full sky survey in galactic coordinates obtained at 408 MHz (wavelength 73 cm), shown in false colors.

Radio intensity is displayed on a linear color scale from dark blue (lowest intensity) to red (highest intensity). The angular resolution of the map is approximately 2°. Many well-known radio sources are visible along the galactic plane, including the supernova remnants of Cassiopeia A and the Crab Nebula.
Complexes of local arms (Swan X and Parus X), surrounded by diffuse radio emission, are clearly visible. The diffuse radio emission of the Milky Way is mainly synchrotron emission from cosmic ray electrons as they interact with the magnetic field of our Galaxy.

Rice. 5 Two full-sky images based on data obtained in 1990 by the DIRBE Diffuse Infrared Background Experiment on the COBE satellite.

Both images show strong radiation from the Milky Way. The top photo shows combined emission data at 25, 60 and 100 micron far infrared wavelengths, shown in blue, green and red respectively. This radiation comes from cold interstellar dust. The pale blue background radiation is generated by interplanetary dust in the solar system. The bottom image combines emission data at wavelengths 1.2, 2.2, and 3.4 microns in the near-infrared, shown in blue, green, and red, respectively.

New map of the Milky Way

The Milky Way can be classified as spiral galaxy. As already said, it consists of a main body in the form of a flat disk with a diameter of more than 100,000 light years, within which lies most of the stars. The disk has a non-compact structure, and its uneven structure is obvious, starting from the core and spreading to the periphery of the Galaxy. These are spiral branches of regions of the highest density of matter, the so-called. spiral arms in which the process of formation of new stars takes place, starting in interstellar gas and dust clouds. Nothing can be said about the reason for the emergence of spiral arms, except that arms always appear in numerical simulations of the birth of a galaxy if the mass and torque are given sufficiently large.

To see the description, touch the cell for a long time To enlarge the image - briefly To return from the image - return key on your phone or browser

A new computer-generated three-dimensional model of the Milky Way with the real location of hundreds of thousands of nebulae and stars.
© National Geographic Society, Washington D.C. 2005.

Rotation of parts of the galaxy

Parts of the galaxy rotate at different speeds around its center. If we could look at the Galaxy “from above”, we would see a dense and bright core, inside which the stars are located very close to each other, as well as arms. In them, stars are concentrated less compactly.

The direction of rotation of the Milky Way, as well as similar spiral galaxies (indicated on the map in the lower left corner when enlarged) is such that the spiral arms seem to twist. And here it is necessary to focus attention on this specific point. During the existence of the Galaxy (at least 12 billion years, according to any modern estimates), the spiral branches would have to spin around the center of the Galaxy several dozen times! And this is not observed either in other galaxies or in ours. Back in 1964, Q. Lin and F. Shu from the USA proposed a theory according to which spiral arms are not some kind of material formations, but waves of matter density that stand out against the smooth background of the galaxy primarily because active star formation is taking place in them, accompanied by the birth of high luminosity stars. The rotation of the spiral arm has nothing to do with the movement of stars in galactic orbits.

At short distances from the core, the orbital velocities of stars exceed the velocity of the arm, and stars “flow” into it from the inside and leave from the outside. At large distances, the opposite is true: the arm seems to run toward the stars, temporarily includes them in its composition, and then overtakes them. As for the bright OB stars that determine the pattern of the sleeve, they, having been born in the sleeve, end their relatively short lives in it, not having time to leave the sleeve during their existence.

The gas ring and the movement of stars

According to one of the hypotheses for the structure of the Milky Way, between the center of the Galaxy and the spiral arms there is also the so-called.

To facilitate the task of stellar kinematics, stars are divided into families according to certain characteristics, age, physical data, and location within the Galaxy. The vast majority of young stars concentrated in spiral arms have a rotation speed (relative to the Galactic center, of course) of several kilometers per second. It is believed that such stars had too little time to interact with other stars; they did not “use” mutual attraction to increase their rotation speed. Middle-aged stars have higher speeds.

Old stars have the highest speed; they are located on a spherical halo surrounding our Galaxy up to a distance of 100,000 light years from the center. Their speed exceeds 100 km/s (like globular star clusters).

In the inner regions, where they are densely concentrated, the Galaxy in its motion manifests itself similarly to a solid body. In these regions, the speed of rotation of stars is directly proportional to their distance from the center. The rotation curve will appear as a straight line.

At the periphery, the Galaxy in motion no longer resembles a solid body. In this part it is not densely “populated” with celestial bodies. The “rotation curve” for the peripheral regions will be “Keplerian”, similar to the rule about the unequal speed of movement of the planets in the Solar System. The rotation speed of stars decreases as they move away from the center of the galaxy.

Star clusters

Not only stars are in constant motion, but also other celestial objects inhabiting the Milky Way: these are open and globular star clusters, nebulae, etc. The movement of globular star clusters - dense formations that include hundreds of thousands of old stars - deserves special study. These clusters have a clear spherical shape; they move around the center of the Galaxy in elongated elliptical orbits inclined to its disk. Their speed of movement averages about two hundred km/s. Globular star clusters cross the disk at intervals of several million years. Being fairly densely grouped formations, they are relatively stable and do not disintegrate under the influence of the gravity of the Milky Way plane. Things are different with open star clusters. They consist of several hundred or thousands of stars, and they are located mainly in spiral arms. The stars there are not so close to each other. It is believed that open star clusters tend to disintegrate after a few billion years of existence. Globular star clusters are old in terms of formation, they can be about ten billion years old, open clusters are much younger (the count goes from a million to tens of millions of years), very rarely their age exceeds one billion years.

Dear visitors!

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.

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.

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.

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.

Currently, the Milky Way is 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. It’s 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.

The starry sky has attracted people's gaze since ancient times. The best minds of all nations tried to comprehend our place in the Universe, imagine and justify its structure. Scientific progress has made it possible to move in the study of the vast expanses of space from romantic and religious constructions to logically verified theories based on numerous factual materials. Now any schoolchild has an idea of ​​what our Galaxy looks like according to the latest research, who, why and when gave it such a poetic name and what its expected future is.

origin of name

The expression “Milky Way Galaxy” is essentially a tautology. Galactikos roughly translated from ancient Greek means “milk”. This is what the inhabitants of the Peloponnese called the cluster of stars in the night sky, attributing its origin to the hot-tempered Hera: the goddess did not want to feed Hercules, the illegitimate son of Zeus, and in anger splashed breast milk. The drops formed a star trail, visible on clear nights. Centuries later, scientists discovered that the observed luminaries are only an insignificant part of existing celestial bodies. They gave the name Galaxy or the Milky Way system to the space of the Universe in which our planet is located. After confirming the assumption of the existence of other similar formations in space, the first term became universal for them.

A look from the inside

Scientific knowledge about the structure of the part of the Universe, including the Solar System, learned little from the ancient Greeks. Understanding of what our Galaxy looks like has evolved from Aristotle's spherical universe to modern theories that include black holes and dark matter.

The fact that Earth is part of the Milky Way system imposes certain limitations on those trying to figure out what shape our Galaxy has. To answer this question unambiguously, a view from the outside is required, and at a great distance from the object of observation. Now science is deprived of such an opportunity. A kind of substitute for an outside observer is the collection of data on the structure of the Galaxy and its correlation with the parameters of other space systems available for study.

The information collected allows us to say with confidence that our Galaxy has the shape of a disk with a thickening (bulge) in the middle and spiral arms diverging from the center. The latter contain the brightest stars in the system. The diameter of the disk is more than 100 thousand light years.

Structure

The center of the Galaxy is hidden by interstellar dust, making it difficult to study the system. Radio astronomy methods help to cope with the problem. Waves of a certain length easily overcome any obstacles and allow you to obtain the much desired image. Our Galaxy, according to the data obtained, has an inhomogeneous structure.

Conventionally, we can distinguish two elements connected with each other: the halo and the disk itself. The first subsystem has the following characteristics:

• the shape is a sphere;

• its center is considered to be a bulge;
• the highest concentration of stars in the halo is characteristic of its middle part; as you approach the edges, the density decreases greatly;
• The rotation of this zone of the galaxy is quite slow;
• the halo mainly contains old stars with relatively low mass;
• a significant space of the subsystem is filled with dark matter.

The density of stars in the galactic disk greatly exceeds the halo. In the sleeves there are young and even just emerging

Center and core

The “heart” of the Milky Way is located in Without studying it, it is difficult to fully understand what our Galaxy is like. The name "core" in scientific writings either refers only to the central region, only a few parsecs in diameter, or includes the bulge and gas ring, considered the birthplace of stars. In what follows, the first version of the term will be used.

Visible light has difficulty penetrating the center of the Milky Way because it encounters a lot of cosmic dust, hiding what our Galaxy looks like. Photos and images taken in the infrared range significantly expand astronomers' knowledge of the nucleus.

Data on the characteristics of radiation in the central part of the Galaxy led scientists to believe that there is a black hole at the core of the nucleus. Its mass is more than 2.5 million times the mass of the Sun. Around this object, according to researchers, another, but less impressive in its parameters, black hole rotates. Modern knowledge about the structural features of space suggests that such objects are located in the central part of most galaxies.

Light and darkness

The combined influence of black holes on the motion of stars makes its own adjustments to the way our Galaxy looks: it leads to specific changes in orbits that are not typical for cosmic bodies, for example, near the Solar system. The study of these trajectories and the relationship between the speed of movement and the distance from the center of the Galaxy formed the basis of the now actively developing theory of dark matter. Its nature is still shrouded in mystery. The presence of dark matter, which supposedly makes up the vast majority of all matter in the Universe, is registered only by the effect of gravity on orbits.

If we dispel all the cosmic dust that hides the core from us, an amazing picture will be revealed. Despite the concentration of dark matter, this part of the Universe is full of light emitted by a huge number of stars. There are hundreds of times more of them per unit of space here than near the Sun. About ten billion of them form a galactic bar, also called a bar, of an unusual shape.

Space nut

Studying the center of the system in the long-wavelength range allowed us to obtain a detailed infrared image. Our Galaxy, as it turns out, has a structure at its core that resembles a peanut in a shell. This “nut” is the bridge, which includes more than 20 million red giants (bright, but less hot stars).

The spiral arms of the Milky Way radiate from the ends of the bar.

The work associated with the discovery of the “peanut” at the center of the star system not only shed light on the structure of our Galaxy, but also helped to understand how it developed. Initially, in the space of space there was an ordinary disk, in which a jumper formed over time. Under the influence of internal processes, the bar changed its shape and began to resemble a nut.

Our home on the space map

The activity occurs both in the bar and in the spiral arms that our Galaxy possesses. They were named after the constellations where sections of the branches were discovered: the arms of Perseus, Cygnus, Centaurus, Sagittarius and Orion. Near the latter (at a distance of at least 28 thousand light years from the core) is the Solar System. This area has certain characteristics that, according to experts, made possible the emergence of life on Earth.

The galaxy and our solar system rotate along with it. The patterns of movement of individual components do not coincide. stars are sometimes included in the spiral branches, sometimes separated from them. Only luminaries lying on the boundary of the corotation circle do not make such “travels”. These include the Sun, protected from powerful processes constantly occurring in the arms. Even a slight shift would negate all other benefits for the development of organisms on our planet.

The sky is in diamonds

The Sun is just one of many similar bodies that our Galaxy is full of. The total number of stars, single or grouped, according to the latest data, exceeds 400 billion. The closest to us, Proxima Centauri, is part of a system of three stars, along with the slightly more distant Alpha Centauri A and Alpha Centauri B. The brightest point of the night sky, Sirius A, is located in Its luminosity, according to various sources, exceeds that of the sun by 17-23 times. Sirius is also not alone; he is accompanied by a satellite bearing a similar name, but marked B.

Children often begin to get acquainted with what our Galaxy looks like by searching the sky for the North Star or Alpha Ursa Minor. It owes its popularity to its position above the North Pole of the Earth. In terms of luminosity, Polaris is significantly higher than Sirius (almost two thousand times brighter than the Sun), but it cannot challenge Alpha Canis Majoris for the title of the brightest due to its distance from Earth (estimated from 300 to 465 light years).

Types of luminaries

Stars differ not only in luminosity and distance from the observer. Each is assigned a certain value (the corresponding parameter of the Sun is taken as one), the degree of surface heating, and color.

Supergiants have the most impressive sizes. Neutron stars have the highest concentration of matter per unit volume. The color characteristic is inextricably linked with temperature:

• reds are the coldest;
• heating the surface to 6,000º, like the Sun, gives rise to a yellow tint;
• white and blue luminaries have a temperature of more than 10,000º.

May vary and reach a maximum shortly before its collapse. Supernova explosions make a huge contribution to understanding what our Galaxy looks like. Photos of this process taken by telescopes are amazing.
The data collected on their basis helped to reconstruct the process that led to the outbreak and predict the fate of a number of cosmic bodies.

The future of the Milky Way

Our Galaxy and other galaxies are constantly in motion and interacting. Astronomers have found that the Milky Way has repeatedly absorbed its neighbors. Similar processes are expected in the future. Over time, it will include the Magellanic Cloud and a number of other dwarf systems. The most impressive event is expected in 3-5 billion years. This will be a collision with the only neighbor that is visible from Earth with the naked eye. As a result, the Milky Way will become an elliptical galaxy.

The endless expanses of space amaze the imagination. It is difficult for the average person to realize the scale of not only the Milky Way or the entire Universe, but even the Earth. However, thanks to the achievements of science, we can imagine at least approximately what kind of grandiose world we are part of.

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.

Astronomers from the European Space Agency (ESA) have been able to more accurately calculate the approximate mass of our galaxy. It turned out to be twice as large as predicted by previous studies. How much? Almost doubled. The findings of a 2016 study suggested that the mass of the Milky Way could be about 750 billion solar masses. ESA specialists indicate a different figure – almost 1.5 trillion. Why such difference?