The Milky Way is the galaxy that contains the Earth, the solar system, and all the individual stars visible to the naked eye. Refers to barred spiral galaxies.

The Milky Way, together with the Andromeda Galaxy (M31), the Triangulum Galaxy (M33) and more than 40 dwarf satellite galaxies - its own and Andromeda - form the Local Group of galaxies, which is part of the Local Supercluster (Virgo Supercluster).

History of discovery

Galileo's discovery

The Milky Way revealed its secret only in 1610. It was then that the first telescope was invented, which was used by Galileo Galilei. The famous scientist saw through the device that the Milky Way was a real cluster of stars, which, when viewed with the naked eye, merged into a continuous, faintly flickering strip. Galileo even managed to explain the heterogeneity of the structure of this band. It was caused by the presence of not only star clusters in the celestial phenomenon. There are also dark clouds there. The combination of these two elements creates an amazing image of a night phenomenon.

William Herschel's discovery

The study of the Milky Way continued into the 18th century. During this period, its most active researcher was William Herschel. The famous composer and musician was engaged in the manufacture of telescopes and studied the science of stars. Herschel's most important discovery was the Great Plan of the Universe. This scientist observed the planets through a telescope and counted them in different parts of the sky. Research has led to the conclusion that the Milky Way is a kind of star island in which our Sun is located. Herschel even drew a schematic plan of his discovery. In the picture, the star system was depicted in the form of a millstone and had an elongated irregular shape. At the same time, the sun was inside this ring that surrounded our world. This is exactly how all scientists imagined our Galaxy until the beginning of the last century.

It was only in the 1920s that the work of Jacobus Kaptein was published, in which the Milky Way was described in the most detail. At the same time, the author gave a diagram of the star island, as similar as possible to the one that is currently known to us. Today we know that the Milky Way is a Galaxy that contains the Solar System, the Earth and those individual stars that are visible to humans with the naked eye.

What shape does the Milky Way have?

When studying galaxies, Edwin Hubble classified them into various types of elliptical and spiral. Spiral galaxies are disk-shaped with spiral arms inside. Since the Milky Way is disk-shaped along with spiral galaxies, it is logical to assume that it is likely a spiral galaxy.

In the 1930s, R. J. Trumpler realized that the estimates of the size of the Milky Way galaxy made by Capetin and other scientists were erroneous because the measurements were based on observations using radiation waves in the visible region of the spectrum. Trumpler concluded that the huge amount of dust in the plane of the Milky Way absorbs visible light. Therefore, distant stars and their clusters seem more ghostly than they really are. Because of this, to accurately image the stars and star clusters inside the Milky Way, astronomers had to find a way to see through the dust.

In the 1950s, the first radio telescopes were invented. Astronomers have discovered that hydrogen atoms emit radiation in radio waves, and that such radio waves can penetrate dust in the Milky Way. Thus, it became possible to see the spiral arms of this galaxy. For this purpose, the marking of stars was used by analogy with marks when measuring distances. Astronomers realized that spectral type O and B stars could serve to achieve this goal.

Such stars have several features:

• brightness– they are very noticeable and often found in small groups or associations;
• warm– they emit waves of different lengths (visible, infrared, radio waves);
• short life time– they live about 100 million years. Given the speed at which stars rotate at the center of the galaxy, they do not travel far from their birthplace.

Astronomers can use radio telescopes to pinpoint the positions of O and B stars and, based on Doppler shifts in the radio spectrum, determine their speed. After performing such operations on many stars, scientists were able to produce combined radio and optical maps of the Milky Way's spiral arms. Each arm is named after the constellation that exists in it.

Astronomers believe that the movement of matter around the center of the galaxy creates density waves (regions of high and low density), just like what you see when you mix cake batter with an electric mixer. These density waves are believed to have caused the spiral nature of the galaxy.

Thus, by viewing the sky at different wavelengths (radio, infrared, visible, ultraviolet, x-ray) using various ground-based and space telescopes, different images of the Milky Way can be obtained.

Doppler effect. Just as the high-pitched sound of a fire truck siren becomes lower as the vehicle moves away, the movement of stars affects the wavelengths of light that travel from them to Earth. This phenomenon is called the Doppler effect. We can measure this effect by measuring the lines in the star's spectrum and comparing them to the spectrum of a standard lamp. The degree of Doppler shift shows how fast the star is moving relative to us. Additionally, the direction of the Doppler shift can tell us the direction in which the star is moving. If the spectrum of a star shifts to the blue end, then the star is moving towards us; if in the red direction, it moves away.

Structure of the Milky Way

If we carefully examine the structure of the Milky Way, we will see the following:

1. Galactic disk. Most of the stars in the Milky Way are concentrated here.

The disk itself is divided into the following parts:

• The nucleus is the center of the disk;
• Arcs are the areas around the nucleus, including the areas directly above and below the plane of the disk.
• Spiral arms are areas that extend outward from the center. Our Solar System is located in one of the spiral arms of the Milky Way.

1. Globular clusters. Several hundred of them are scattered above and below the plane of the disk.
2. Halo. This is a large, dim region that surrounds the entire galaxy. The halo consists of high-temperature gas and possibly dark matter.

The radius of the halo is significantly larger than the size of the disk and, according to some data, reaches several hundred thousand light years. The center of symmetry of the Milky Way halo coincides with the center of the galactic disk. The halo consists mainly of very old, dim stars. The age of the spherical component of the Galaxy exceeds 12 billion years. The central, densest part of the halo within several thousand light years from the center of the Galaxy is called bulge(translated from English as “thickening”). The halo as a whole rotates very slowly.

Compared to halo disk spins noticeably faster. It looks like two plates folded at the edges. The diameter of the Galaxy's disk is about 30 kpc (100,000 light years). The thickness is about 1000 light years. The rotation speed is not the same at different distances from the center. It quickly increases from zero in the center to 200-240 km/s at a distance of 2 thousand light years from it. The mass of the disk is 150 billion times greater than the mass of the Sun (1.99 * 10 30 kg). Young stars and star clusters are concentrated in the disk. Among them are many bright and hot stars. The gas in the galactic disk is distributed unevenly, forming giant clouds. The main chemical element in our Galaxy is hydrogen. Approximately 1/4 of it consists of helium.

One of the most interesting regions of the Galaxy is its center, or core, located in the direction of the constellation Sagittarius. The visible radiation from the central regions of the Galaxy is completely hidden from us by thick layers of absorbing matter. Therefore, it began to be studied only after the creation of receivers for infrared and radio radiation, which are absorbed to a lesser extent. The central regions of the Galaxy are characterized by a strong concentration of stars: there are many thousands of them in each cubic parsec. Closer to the center, areas of ionized hydrogen and numerous sources of infrared radiation are noted, indicating star formation occurring there. In the very center of the Galaxy, the existence of a massive compact object is assumed - a black hole with a mass of about a million solar masses.

One of the most notable formations is spiral branches (or sleeves). They gave the name to this type of objects – spiral galaxies. Along the arms are mainly concentrated the youngest stars, many open star clusters, as well as chains of dense clouds of interstellar gas in which stars continue to form. Unlike a halo, where any manifestations of stellar activity are extremely rare, vigorous life continues in the branches, associated with the continuous transition of matter from interstellar space to stars and back. The spiral arms of the Milky Way are largely hidden from us by absorbing matter. Their detailed study began after the advent of radio telescopes. They made it possible to study the structure of the Galaxy by observing the radio emission of interstellar hydrogen atoms concentrated along long spirals. According to modern concepts, spiral arms are associated with compression waves propagating across the galactic disk. Passing through regions of compression, the matter of the disk becomes denser, and the formation of stars from gas becomes more intense. The reasons for the appearance of such a unique wave structure in the disks of spiral galaxies are not entirely clear. Many astrophysicists are working on this problem.

The Sun's Place in the Galaxy

In the vicinity of the Sun, it is possible to trace sections of two spiral branches, distant from us by about 3 thousand light years. Based on the constellations where these areas are found, they are called the Sagittarius arm and the Perseus arm. The sun is almost halfway between these spiral arms. True, relatively close (by galactic standards) to us, in the constellation Orion, there passes another, not so clearly expressed branch, which is considered a branch of one of the main spiral arms of the Galaxy.

The distance from the Sun to the center of the Galaxy is 23-28 thousand light years, or 7-9 thousand parsecs. This suggests that the Sun is located closer to the outskirts of the disk than to its center.

Together with all nearby stars, the Sun rotates around the center of the Galaxy at a speed of 220–240 km/s, completing one revolution in approximately 200 million years. This means that during its entire existence, the Earth has flown around the center of the Galaxy no more than 30 times.

The speed of rotation of the Sun around the center of the Galaxy practically coincides with the speed with which the compaction wave, forming the spiral arm, moves in this region. This situation is generally unusual for the Galaxy: the spiral branches rotate at a constant angular velocity, like the spokes of a wheel, and the movement of stars, as we have seen, obeys a completely different pattern. Therefore, almost the entire stellar population of the disk either falls inside the spiral branch or leaves it. The only place where the velocities of stars and spiral arms coincide is the so-called corotation circle, and it is on it that the Sun is located!

This circumstance is extremely favorable for the Earth. Indeed, violent processes occur in the spiral branches, generating powerful radiation that is destructive for all living things. And no atmosphere could protect from it. But our planet exists in a relatively calm place in the Galaxy and for hundreds of millions and billions of years has not experienced the influence of these cosmic cataclysms. Perhaps this is why life could originate and survive on Earth.

For a long time, the position of the Sun among the stars was considered the most ordinary. Today we know that this is not so: in a certain sense it is privileged. And this must be taken into account when discussing the possibility of the existence of life in other parts of our Galaxy.

Location of stars

In a cloudless night sky, the Milky Way is visible from anywhere on our planet. However, only part of the Galaxy is accessible to human eyes, which is a system of stars located inside the Orion arm. What is the Milky Way? The definition of all its parts in space becomes most clear if we consider a star map. In this case, it becomes clear that the Sun, which illuminates the Earth, is located almost on the disk. This is almost the edge of the Galaxy, where the distance from the core is 26-28 thousand light years. Moving at a speed of 240 kilometers per hour, the Sun spends 200 million years on one revolution around the core, so during its entire existence it traveled around the disk, circling the core, only thirty times. Our planet is located in the so-called corotation circle. This is a place where the rotation speeds of the arms and stars are identical. This circle is characterized by an increased level of radiation. That is why life, as scientists believe, could only arise on that planet near which there are a small number of stars. Our Earth was such a planet. It is located on the periphery of the Galaxy, in its quietest place. This is why there have been no global cataclysms on our planet for several billion years, which often occur in the Universe.

What will the death of the Milky Way look like?

The cosmic story of the death of our galaxy begins here and now. We may look around blindly, thinking that the Milky Way, Andromeda (our big sister) and a bunch of unknowns - our cosmic neighbors - are our home, but in reality there is much more to it. It's time to explore what else is around us. Go.

• Triangulum Galaxy. With a mass of approximately 5% of the Milky Way's mass, it is the third largest galaxy in the local group. It has a spiral structure, its own satellites and may be a satellite of the Andromeda galaxy.
• Large Magellanic Cloud. This galaxy makes up only 1% of the mass of the Milky Way, but is the fourth largest in our local group. It is very close to our Milky Way—less than 200,000 light-years away—and is undergoing active star formation as tidal interactions with our galaxy cause gas to collapse and produce new, hotter, larger stars in the Universe.
• Small Magellanic Cloud, NGC 3190 and NGC 6822. All of them have a mass between 0.1% and 0.6% of the Milky Way (and it is not clear which is larger) and all three are independent galaxies. Each of them contains more than a billion solar masses of material.
• Elliptical galaxies M32 and M110. They may be "only" satellites of Andromeda, but they each have more than a billion stars, and they may even be more massive than numbers 5, 6, and 7.

In addition, there are at least 45 other known smaller galaxies that make up our local group. Each of them has a halo of dark matter surrounding it; each of them is gravitationally tied to the other, located at a distance of 3 million light years. Despite their size, mass and size, none of them will remain in a few billion years.

So, the main thing

As time passes, galaxies interact gravitationally. They not only pull together due to gravitational attraction, but also interact tidally. We usually talk about tides in the context of the Moon pulling on Earth's oceans and creating high and low tides, and this is partly true. But from a galactic perspective, tides are a less noticeable process. The part of a small galaxy that is close to a large one will be attracted with greater gravitational force, and the part that is further away will experience less gravity. As a result, the small galaxy will stretch out and eventually break apart under the influence of gravity.

Small galaxies that are part of our local group, including both Magellanic clouds and dwarf elliptical galaxies, will be torn apart in this way, and their material will be included in the large galaxies with which they merge. “So what,” you say. After all, this is not completely death, because large galaxies will remain alive. But even they will not exist forever in this state. In 4 billion years, the mutual gravitational pull of the Milky Way and Andromeda will pull the galaxies into a gravitational dance that will lead to a great merger. Although this process will take billions of years, the spiral structure of both galaxies will be destroyed, resulting in the creation of a single, giant elliptical galaxy at the core of our local group: Mammals.

A small percentage of stars will be ejected during such a merger, but most will remain intact and there will be a large burst of star formation. Eventually, the rest of the galaxies in our local group will also be sucked in, leaving one big giant galaxy that has devoured the rest. This process will occur in all connected groups and clusters of galaxies throughout the Universe, while dark energy pushes individual groups and clusters away from each other. But this cannot be called death, because the galaxy will remain. And it will be like this for some time. But the galaxy is made of stars, dust and gas, and everything will come to an end someday.

Throughout the Universe, galactic mergers will take place over tens of billions of years. During the same time, dark energy will drag them throughout the Universe to a state of complete solitude and inaccessibility. And although the last galaxies outside our local group will not disappear until hundreds of billions of years have passed, the stars in them will live. The longest-lived stars in existence today will continue to burn their fuel for tens of trillions of years, and new stars will emerge from the gas, dust and stellar corpses that populate every galaxy - albeit fewer and fewer.

When the last stars burn out, only their corpses will remain - white dwarfs and neutron stars. They will shine for hundreds of trillions or even quadrillions of years before they go out. When that inevitable happens, we'll be left with brown dwarfs (failed stars) that randomly merge, reignite nuclear fusion, and create starlight over tens of trillions of years.

When the last star goes out tens of quadrillions of years in the future, there will still be some mass left in the galaxy. This means that this cannot be called “true death.”

All masses gravitationally interact with each other, and gravitational objects of different masses exhibit strange properties when interacting:

• Repeated “approaches” and close passes cause exchanges of speed and impulses between them.
• Objects with low mass are ejected from the galaxy, and objects with higher mass sink into the center, losing speed.
• Over a sufficiently long period of time, most of the mass will be ejected, and only a small part of the remaining mass will be firmly attached.

At the very center of these galactic remains there will be a supermassive black hole in every galaxy, and the rest of the galactic objects will orbit a larger version of our own solar system. Of course, this structure will be the last, and since the black hole will be as large as possible, it will eat everything it can reach. At the center of Milkomeda there will be an object hundreds of millions of times more massive than our Sun.

But this will come to an end too?

Thanks to the phenomenon of Hawking radiation, even these objects will one day decay. It will take about 10,80 to 10,100 years, depending on how massive our supermassive black hole becomes as it grows, but the end is coming. After this, the remains orbiting around the galactic center will unravel and leave only a halo of dark matter, which can also randomly dissociate, depending on the properties of this very matter. Without any matter there will no longer be anything that we once called the local group, the Milky Way and other names dear to our hearts.

Mythology

Armenian, Arabic, Wallachian, Jewish, Persian, Turkish, Kyrgyz

According to one of the Armenian myths about the Milky Way, the god Vahagn, the ancestor of the Armenians, stole straw from the ancestor of the Assyrians, Barsham, in the harsh winter and disappeared into the sky. When he walked with his prey across the sky, he dropped straws on his way; from them a light trail was formed in the sky (in Armenian “Straw Thief Road”). The myth of scattered straw is also spoken of in Arabic, Jewish, Persian, Turkish and Kyrgyz names (Kirg. Samanchyn Zholu– the strawman’s path) of this phenomenon. The people of Wallachia believed that Venus stole this straw from St. Peter.

Buryat

According to Buryat mythology, good forces create peace and change the universe. Thus, the Milky Way arose from the milk that Manzan Gourmet strained from her breast and splashed out after Abai Geser, who deceived her. According to another version, the Milky Way is a “seam of the sky”, sewn up after the stars poured out of it; Tengris walk along it, like on a bridge.

Hungarian

According to Hungarian legend, Attila would descend the Milky Way if the Székelys were in danger; the stars represent sparks from hooves. Milky Way. accordingly, it is called the “road of warriors.”

Ancient Greek

Etymology of the word Galaxias (Γαλαξίας) and its connection with milk (γάλα) are revealed by two similar ancient Greek myths. One of the legends tells about the mother’s milk spilling across the sky from the goddess Hera, who was breastfeeding Hercules. When Hera learned that the baby she was nursing was not her own child, but the illegitimate son of Zeus and an earthly woman, she pushed him away, and the spilled milk became the Milky Way. Another legend says that the spilled milk was the milk of Rhea, the wife of Kronos, and the baby was Zeus himself. Kronos devoured his children because it was foretold that he would be overthrown by his own son. Rhea hatched a plan to save her sixth child, newborn Zeus. She wrapped a stone in baby clothes and slipped it to Kronos. Kronos asked her to feed her son one more time before he swallowed him. The milk spilled from Rhea's breast onto a bare rock later became known as the Milky Way.

Indian

Ancient Indians considered the Milky Way to be the milk of the evening red cow passing across the sky. In the Rig Veda, the Milky Way is called the throne road of Aryaman. The Bhagavata Purana contains a version according to which the Milky Way is the belly of a celestial dolphin.

Inca

The main objects of observation in Inca astronomy (which was reflected in their mythology) in the sky were the dark areas of the Milky Way - peculiar “constellations” in the terminology of Andean cultures: Lama, Baby Lama, Shepherd, Condor, Partridge, Toad, Snake, Fox; as well as the stars: Southern Cross, Pleiades, Lyra and many others.

Ketskaya

In Ket myths, similar to the Selkup ones, the Milky Way is described as the road of one of three mythological characters: the Son of Heaven (Esya), who went hunting to the western side of the sky and froze there, the hero Albe, who pursued the evil goddess, or the first shaman Doha, who climbed this road to the sun.

Chinese, Vietnamese, Korean, Japanese

In the mythologies of the Sinosphere, the Milky Way is called and compared to a river (in Vietnamese, Chinese, Korean and Japanese the name “silver river” is retained). The Chinese also sometimes called the Milky Way the “Yellow Road”, after the color of the straw.

Indigenous peoples of North America

The Hidatsa and Eskimos call the Milky Way "The Ash". Their myths tell of a girl who scattered ashes across the sky so that people could find their way home at night. The Cheyenne believed that the Milky Way was mud and silt raised by the belly of a turtle swimming through the sky. Eskimos from the Bering Strait - that these are the traces of the Creator Raven walking across the sky. The Cherokees believed that the Milky Way was formed when one hunter stole the wife of another out of jealousy, and her dog began to eat cornmeal left unattended and scattered it across the sky (the same myth is found among the Khoisan people of the Kalahari). Another myth of the same people says that the Milky Way is the footprint of a dog dragging something across the sky. The Ktunaha called the Milky Way the “tail of the dog,” and the Blackfoot called it the “wolf road.” Wyandot myth says that the Milky Way is a place where the souls of dead people and dogs come together and dance.

Maori

In Maori mythology, the Milky Way is considered the boat of Tama-rereti. The bow of the boat is the constellation Orion and Scorpio, the anchor is the Southern Cross, Alpha Centauri and Hadar are the rope. According to legend, one day Tama-rereti was sailing in his canoe and saw that it was late and he was far from home. There were no stars in the sky, and, fearing that Tanifa might attack, Tama-rereti began throwing sparkling pebbles into the sky. The heavenly deity Ranginui liked what he was doing and placed Tama-rereti's boat in the sky and turned the pebbles into stars.

Finnish, Lithuanian, Estonian, Erzya, Kazakh

The Finnish name is Finnish. Linnunrata– means “Way of the Birds”; the Lithuanian name has a similar etymology. Estonian myth also connects the Milky Way with bird flight.

The Erzya name is “Kargon Ki” (“Crane Road”).

The Kazakh name is “Kus Zholy” (“Path of the Birds”).

Interesting facts about the Milky Way galaxy

• The Milky Way began forming as a cluster of dense regions after the Big Bang. The first stars to appear were in globular clusters, which continue to exist. These are the oldest stars in the galaxy;
• The galaxy increased its parameters due to absorption and merger with others. It is now taking stars from the Sagittarius Dwarf Galaxy and the Magellanic Clouds;
• The Milky Way moves through space with an acceleration of 550 km/s relative to the cosmic microwave background radiation;
• The supermassive black hole Sagittarius A* lurks at the galactic center. Its mass is 4.3 million times greater than that of the Sun;
• Gas, dust and stars rotate around the center at a speed of 220 km/s. This is a stable indicator, implying the presence of a dark matter shell;
• In 5 billion years, a collision with the Andromeda Galaxy is expected.

The Milky Way is the galaxy that contains the Earth, the solar system, and all the individual stars visible to the naked eye. Refers to barred spiral galaxies.

The Milky Way, together with the Andromeda Galaxy (M31), the Triangulum Galaxy (M33) and more than 40 dwarf satellite galaxies - its own and Andromeda - form the Local Group of galaxies, which is part of the Local Supercluster (Virgo Supercluster).

History of discovery

Galileo's discovery

The Milky Way revealed its secret only in 1610. It was then that the first telescope was invented, which was used by Galileo Galilei. The famous scientist saw through the device that the Milky Way was a real cluster of stars, which, when viewed with the naked eye, merged into a continuous, faintly flickering strip. Galileo even managed to explain the heterogeneity of the structure of this band. It was caused by the presence of not only star clusters in the celestial phenomenon. There are also dark clouds there. The combination of these two elements creates an amazing image of a night phenomenon.

William Herschel's discovery

The study of the Milky Way continued into the 18th century. During this period, its most active researcher was William Herschel. The famous composer and musician was engaged in the manufacture of telescopes and studied the science of stars. Herschel's most important discovery was the Great Plan of the Universe. This scientist observed the planets through a telescope and counted them in different parts of the sky. Research has led to the conclusion that the Milky Way is a kind of star island in which our Sun is located. Herschel even drew a schematic plan of his discovery. In the picture, the star system was depicted in the form of a millstone and had an elongated irregular shape. At the same time, the sun was inside this ring that surrounded our world. This is exactly how all scientists imagined our Galaxy until the beginning of the last century.

It was only in the 1920s that the work of Jacobus Kaptein was published, in which the Milky Way was described in the most detail. At the same time, the author gave a diagram of the star island, as similar as possible to the one that is currently known to us. Today we know that the Milky Way is a Galaxy that contains the Solar System, the Earth and those individual stars that are visible to humans with the naked eye.

What shape does the Milky Way have?

When studying galaxies, Edwin Hubble classified them into various types of elliptical and spiral. Spiral galaxies are disk-shaped with spiral arms inside. Since the Milky Way is disk-shaped along with spiral galaxies, it is logical to assume that it is likely a spiral galaxy.

In the 1930s, R. J. Trumpler realized that the estimates of the size of the Milky Way galaxy made by Capetin and other scientists were erroneous because the measurements were based on observations using radiation waves in the visible region of the spectrum. Trumpler concluded that the huge amount of dust in the plane of the Milky Way absorbs visible light. Therefore, distant stars and their clusters seem more ghostly than they really are. Because of this, to accurately image the stars and star clusters inside the Milky Way, astronomers had to find a way to see through the dust.

In the 1950s, the first radio telescopes were invented. Astronomers have discovered that hydrogen atoms emit radiation in radio waves, and that such radio waves can penetrate dust in the Milky Way. Thus, it became possible to see the spiral arms of this galaxy. For this purpose, the marking of stars was used by analogy with marks when measuring distances. Astronomers realized that spectral type O and B stars could serve to achieve this goal.

Such stars have several features:

• brightness– they are very noticeable and often found in small groups or associations;
• warm– they emit waves of different lengths (visible, infrared, radio waves);
• short life time– they live about 100 million years. Given the speed at which stars rotate at the center of the galaxy, they do not travel far from their birthplace.

Astronomers can use radio telescopes to pinpoint the positions of O and B stars and, based on Doppler shifts in the radio spectrum, determine their speed. After performing such operations on many stars, scientists were able to produce combined radio and optical maps of the Milky Way's spiral arms. Each arm is named after the constellation that exists in it.

Astronomers believe that the movement of matter around the center of the galaxy creates density waves (regions of high and low density), just like what you see when you mix cake batter with an electric mixer. These density waves are believed to have caused the spiral nature of the galaxy.

Thus, by viewing the sky at different wavelengths (radio, infrared, visible, ultraviolet, x-ray) using various ground-based and space telescopes, different images of the Milky Way can be obtained.

Doppler effect. Just as the high-pitched sound of a fire truck siren becomes lower as the vehicle moves away, the movement of stars affects the wavelengths of light that travel from them to Earth. This phenomenon is called the Doppler effect. We can measure this effect by measuring the lines in the star's spectrum and comparing them to the spectrum of a standard lamp. The degree of Doppler shift shows how fast the star is moving relative to us. Additionally, the direction of the Doppler shift can tell us the direction in which the star is moving. If the spectrum of a star shifts to the blue end, then the star is moving towards us; if in the red direction, it moves away.

Structure of the Milky Way

If we carefully examine the structure of the Milky Way, we will see the following:

1. Galactic disk. Most of the stars in the Milky Way are concentrated here.

The disk itself is divided into the following parts:

• The nucleus is the center of the disk;
• Arcs are the areas around the nucleus, including the areas directly above and below the plane of the disk.
• Spiral arms are areas that extend outward from the center. Our Solar System is located in one of the spiral arms of the Milky Way.

1. Globular clusters. Several hundred of them are scattered above and below the plane of the disk.
2. Halo. This is a large, dim region that surrounds the entire galaxy. The halo consists of high-temperature gas and possibly dark matter.

The radius of the halo is significantly larger than the size of the disk and, according to some data, reaches several hundred thousand light years. The center of symmetry of the Milky Way halo coincides with the center of the galactic disk. The halo consists mainly of very old, dim stars. The age of the spherical component of the Galaxy exceeds 12 billion years. The central, densest part of the halo within several thousand light years from the center of the Galaxy is called bulge(translated from English as “thickening”). The halo as a whole rotates very slowly.

Compared to halo disk spins noticeably faster. It looks like two plates folded at the edges. The diameter of the Galaxy's disk is about 30 kpc (100,000 light years). The thickness is about 1000 light years. The rotation speed is not the same at different distances from the center. It quickly increases from zero in the center to 200-240 km/s at a distance of 2 thousand light years from it. The mass of the disk is 150 billion times greater than the mass of the Sun (1.99 * 10 30 kg). Young stars and star clusters are concentrated in the disk. Among them are many bright and hot stars. The gas in the galactic disk is distributed unevenly, forming giant clouds. The main chemical element in our Galaxy is hydrogen. Approximately 1/4 of it consists of helium.

One of the most interesting regions of the Galaxy is its center, or core, located in the direction of the constellation Sagittarius. The visible radiation from the central regions of the Galaxy is completely hidden from us by thick layers of absorbing matter. Therefore, it began to be studied only after the creation of receivers for infrared and radio radiation, which are absorbed to a lesser extent. The central regions of the Galaxy are characterized by a strong concentration of stars: there are many thousands of them in each cubic parsec. Closer to the center, areas of ionized hydrogen and numerous sources of infrared radiation are noted, indicating star formation occurring there. In the very center of the Galaxy, the existence of a massive compact object is assumed - a black hole with a mass of about a million solar masses.

One of the most notable formations is spiral branches (or sleeves). They gave the name to this type of objects – spiral galaxies. Along the arms are mainly concentrated the youngest stars, many open star clusters, as well as chains of dense clouds of interstellar gas in which stars continue to form. Unlike a halo, where any manifestations of stellar activity are extremely rare, vigorous life continues in the branches, associated with the continuous transition of matter from interstellar space to stars and back. The spiral arms of the Milky Way are largely hidden from us by absorbing matter. Their detailed study began after the advent of radio telescopes. They made it possible to study the structure of the Galaxy by observing the radio emission of interstellar hydrogen atoms concentrated along long spirals. According to modern concepts, spiral arms are associated with compression waves propagating across the galactic disk. Passing through regions of compression, the matter of the disk becomes denser, and the formation of stars from gas becomes more intense. The reasons for the appearance of such a unique wave structure in the disks of spiral galaxies are not entirely clear. Many astrophysicists are working on this problem.

The Sun's Place in the Galaxy

In the vicinity of the Sun, it is possible to trace sections of two spiral branches, distant from us by about 3 thousand light years. Based on the constellations where these areas are found, they are called the Sagittarius arm and the Perseus arm. The sun is almost halfway between these spiral arms. True, relatively close (by galactic standards) to us, in the constellation Orion, there passes another, not so clearly expressed branch, which is considered a branch of one of the main spiral arms of the Galaxy.

The distance from the Sun to the center of the Galaxy is 23-28 thousand light years, or 7-9 thousand parsecs. This suggests that the Sun is located closer to the outskirts of the disk than to its center.

Together with all nearby stars, the Sun rotates around the center of the Galaxy at a speed of 220–240 km/s, completing one revolution in approximately 200 million years. This means that during its entire existence, the Earth has flown around the center of the Galaxy no more than 30 times.

The speed of rotation of the Sun around the center of the Galaxy practically coincides with the speed with which the compaction wave, forming the spiral arm, moves in this region. This situation is generally unusual for the Galaxy: the spiral branches rotate at a constant angular velocity, like the spokes of a wheel, and the movement of stars, as we have seen, obeys a completely different pattern. Therefore, almost the entire stellar population of the disk either falls inside the spiral branch or leaves it. The only place where the velocities of stars and spiral arms coincide is the so-called corotation circle, and it is on it that the Sun is located!

This circumstance is extremely favorable for the Earth. Indeed, violent processes occur in the spiral branches, generating powerful radiation that is destructive for all living things. And no atmosphere could protect from it. But our planet exists in a relatively calm place in the Galaxy and for hundreds of millions and billions of years has not experienced the influence of these cosmic cataclysms. Perhaps this is why life could originate and survive on Earth.

For a long time, the position of the Sun among the stars was considered the most ordinary. Today we know that this is not so: in a certain sense it is privileged. And this must be taken into account when discussing the possibility of the existence of life in other parts of our Galaxy.

Location of stars

In a cloudless night sky, the Milky Way is visible from anywhere on our planet. However, only part of the Galaxy is accessible to human eyes, which is a system of stars located inside the Orion arm. What is the Milky Way? The definition of all its parts in space becomes most clear if we consider a star map. In this case, it becomes clear that the Sun, which illuminates the Earth, is located almost on the disk. This is almost the edge of the Galaxy, where the distance from the core is 26-28 thousand light years. Moving at a speed of 240 kilometers per hour, the Sun spends 200 million years on one revolution around the core, so during its entire existence it traveled around the disk, circling the core, only thirty times. Our planet is located in the so-called corotation circle. This is a place where the rotation speeds of the arms and stars are identical. This circle is characterized by an increased level of radiation. That is why life, as scientists believe, could only arise on that planet near which there are a small number of stars. Our Earth was such a planet. It is located on the periphery of the Galaxy, in its quietest place. This is why there have been no global cataclysms on our planet for several billion years, which often occur in the Universe.

What will the death of the Milky Way look like?

The cosmic story of the death of our galaxy begins here and now. We may look around blindly, thinking that the Milky Way, Andromeda (our big sister) and a bunch of unknowns - our cosmic neighbors - are our home, but in reality there is much more to it. It's time to explore what else is around us. Go.

• Triangulum Galaxy. With a mass of approximately 5% of the Milky Way's mass, it is the third largest galaxy in the local group. It has a spiral structure, its own satellites and may be a satellite of the Andromeda galaxy.
• Large Magellanic Cloud. This galaxy makes up only 1% of the mass of the Milky Way, but is the fourth largest in our local group. It is very close to our Milky Way—less than 200,000 light-years away—and is undergoing active star formation as tidal interactions with our galaxy cause gas to collapse and produce new, hotter, larger stars in the Universe.
• Small Magellanic Cloud, NGC 3190 and NGC 6822. All of them have a mass between 0.1% and 0.6% of the Milky Way (and it is not clear which is larger) and all three are independent galaxies. Each of them contains more than a billion solar masses of material.
• Elliptical galaxies M32 and M110. They may be "only" satellites of Andromeda, but they each have more than a billion stars, and they may even be more massive than numbers 5, 6, and 7.

In addition, there are at least 45 other known smaller galaxies that make up our local group. Each of them has a halo of dark matter surrounding it; each of them is gravitationally tied to the other, located at a distance of 3 million light years. Despite their size, mass and size, none of them will remain in a few billion years.

So, the main thing

As time passes, galaxies interact gravitationally. They not only pull together due to gravitational attraction, but also interact tidally. We usually talk about tides in the context of the Moon pulling on Earth's oceans and creating high and low tides, and this is partly true. But from a galactic perspective, tides are a less noticeable process. The part of a small galaxy that is close to a large one will be attracted with greater gravitational force, and the part that is further away will experience less gravity. As a result, the small galaxy will stretch out and eventually break apart under the influence of gravity.

Small galaxies that are part of our local group, including both Magellanic clouds and dwarf elliptical galaxies, will be torn apart in this way, and their material will be included in the large galaxies with which they merge. “So what,” you say. After all, this is not completely death, because large galaxies will remain alive. But even they will not exist forever in this state. In 4 billion years, the mutual gravitational pull of the Milky Way and Andromeda will pull the galaxies into a gravitational dance that will lead to a great merger. Although this process will take billions of years, the spiral structure of both galaxies will be destroyed, resulting in the creation of a single, giant elliptical galaxy at the core of our local group: Mammals.

A small percentage of stars will be ejected during such a merger, but most will remain intact and there will be a large burst of star formation. Eventually, the rest of the galaxies in our local group will also be sucked in, leaving one big giant galaxy that has devoured the rest. This process will occur in all connected groups and clusters of galaxies throughout the Universe, while dark energy pushes individual groups and clusters away from each other. But this cannot be called death, because the galaxy will remain. And it will be like this for some time. But the galaxy is made of stars, dust and gas, and everything will come to an end someday.

Throughout the Universe, galactic mergers will take place over tens of billions of years. During the same time, dark energy will drag them throughout the Universe to a state of complete solitude and inaccessibility. And although the last galaxies outside our local group will not disappear until hundreds of billions of years have passed, the stars in them will live. The longest-lived stars in existence today will continue to burn their fuel for tens of trillions of years, and new stars will emerge from the gas, dust and stellar corpses that populate every galaxy - albeit fewer and fewer.

When the last stars burn out, only their corpses will remain - white dwarfs and neutron stars. They will shine for hundreds of trillions or even quadrillions of years before they go out. When that inevitable happens, we'll be left with brown dwarfs (failed stars) that randomly merge, reignite nuclear fusion, and create starlight over tens of trillions of years.

When the last star goes out tens of quadrillions of years in the future, there will still be some mass left in the galaxy. This means that this cannot be called “true death.”

All masses gravitationally interact with each other, and gravitational objects of different masses exhibit strange properties when interacting:

• Repeated “approaches” and close passes cause exchanges of speed and impulses between them.
• Objects with low mass are ejected from the galaxy, and objects with higher mass sink into the center, losing speed.
• Over a sufficiently long period of time, most of the mass will be ejected, and only a small part of the remaining mass will be firmly attached.

At the very center of these galactic remains there will be a supermassive black hole in every galaxy, and the rest of the galactic objects will orbit a larger version of our own solar system. Of course, this structure will be the last, and since the black hole will be as large as possible, it will eat everything it can reach. At the center of Milkomeda there will be an object hundreds of millions of times more massive than our Sun.

But this will come to an end too?

Thanks to the phenomenon of Hawking radiation, even these objects will one day decay. It will take about 10,80 to 10,100 years, depending on how massive our supermassive black hole becomes as it grows, but the end is coming. After this, the remains orbiting around the galactic center will unravel and leave only a halo of dark matter, which can also randomly dissociate, depending on the properties of this very matter. Without any matter there will no longer be anything that we once called the local group, the Milky Way and other names dear to our hearts.

Mythology

Armenian, Arabic, Wallachian, Jewish, Persian, Turkish, Kyrgyz

According to one of the Armenian myths about the Milky Way, the god Vahagn, the ancestor of the Armenians, stole straw from the ancestor of the Assyrians, Barsham, in the harsh winter and disappeared into the sky. When he walked with his prey across the sky, he dropped straws on his way; from them a light trail was formed in the sky (in Armenian “Straw Thief Road”). The myth of scattered straw is also spoken of in Arabic, Jewish, Persian, Turkish and Kyrgyz names (Kirg. Samanchyn Zholu– the strawman’s path) of this phenomenon. The people of Wallachia believed that Venus stole this straw from St. Peter.

Buryat

According to Buryat mythology, good forces create peace and change the universe. Thus, the Milky Way arose from the milk that Manzan Gourmet strained from her breast and splashed out after Abai Geser, who deceived her. According to another version, the Milky Way is a “seam of the sky”, sewn up after the stars poured out of it; Tengris walk along it, like on a bridge.

Hungarian

According to Hungarian legend, Attila would descend the Milky Way if the Székelys were in danger; the stars represent sparks from hooves. Milky Way. accordingly, it is called the “road of warriors.”

Ancient Greek

Etymology of the word Galaxias (Γαλαξίας) and its connection with milk (γάλα) are revealed by two similar ancient Greek myths. One of the legends tells about the mother’s milk spilling across the sky from the goddess Hera, who was breastfeeding Hercules. When Hera learned that the baby she was nursing was not her own child, but the illegitimate son of Zeus and an earthly woman, she pushed him away, and the spilled milk became the Milky Way. Another legend says that the spilled milk was the milk of Rhea, the wife of Kronos, and the baby was Zeus himself. Kronos devoured his children because it was foretold that he would be overthrown by his own son. Rhea hatched a plan to save her sixth child, newborn Zeus. She wrapped a stone in baby clothes and slipped it to Kronos. Kronos asked her to feed her son one more time before he swallowed him. The milk spilled from Rhea's breast onto a bare rock later became known as the Milky Way.

Indian

Ancient Indians considered the Milky Way to be the milk of the evening red cow passing across the sky. In the Rig Veda, the Milky Way is called the throne road of Aryaman. The Bhagavata Purana contains a version according to which the Milky Way is the belly of a celestial dolphin.

Inca

The main objects of observation in Inca astronomy (which was reflected in their mythology) in the sky were the dark areas of the Milky Way - peculiar “constellations” in the terminology of Andean cultures: Lama, Baby Lama, Shepherd, Condor, Partridge, Toad, Snake, Fox; as well as the stars: Southern Cross, Pleiades, Lyra and many others.

Ketskaya

In Ket myths, similar to the Selkup ones, the Milky Way is described as the road of one of three mythological characters: the Son of Heaven (Esya), who went hunting to the western side of the sky and froze there, the hero Albe, who pursued the evil goddess, or the first shaman Doha, who climbed this road to the sun.

Chinese, Vietnamese, Korean, Japanese

In the mythologies of the Sinosphere, the Milky Way is called and compared to a river (in Vietnamese, Chinese, Korean and Japanese the name “silver river” is retained). The Chinese also sometimes called the Milky Way the “Yellow Road”, after the color of the straw.

Indigenous peoples of North America

The Hidatsa and Eskimos call the Milky Way "The Ash". Their myths tell of a girl who scattered ashes across the sky so that people could find their way home at night. The Cheyenne believed that the Milky Way was mud and silt raised by the belly of a turtle swimming through the sky. Eskimos from the Bering Strait - that these are the traces of the Creator Raven walking across the sky. The Cherokees believed that the Milky Way was formed when one hunter stole the wife of another out of jealousy, and her dog began to eat cornmeal left unattended and scattered it across the sky (the same myth is found among the Khoisan people of the Kalahari). Another myth of the same people says that the Milky Way is the footprint of a dog dragging something across the sky. The Ktunaha called the Milky Way the “tail of the dog,” and the Blackfoot called it the “wolf road.” Wyandot myth says that the Milky Way is a place where the souls of dead people and dogs come together and dance.

Maori

In Maori mythology, the Milky Way is considered the boat of Tama-rereti. The bow of the boat is the constellation Orion and Scorpio, the anchor is the Southern Cross, Alpha Centauri and Hadar are the rope. According to legend, one day Tama-rereti was sailing in his canoe and saw that it was late and he was far from home. There were no stars in the sky, and, fearing that Tanifa might attack, Tama-rereti began throwing sparkling pebbles into the sky. The heavenly deity Ranginui liked what he was doing and placed Tama-rereti's boat in the sky and turned the pebbles into stars.

Finnish, Lithuanian, Estonian, Erzya, Kazakh

The Finnish name is Finnish. Linnunrata– means “Way of the Birds”; the Lithuanian name has a similar etymology. Estonian myth also connects the Milky Way with bird flight.

The Erzya name is “Kargon Ki” (“Crane Road”).

The Kazakh name is “Kus Zholy” (“Path of the Birds”).

Interesting facts about the Milky Way galaxy

• The Milky Way began forming as a cluster of dense regions after the Big Bang. The first stars to appear were in globular clusters, which continue to exist. These are the oldest stars in the galaxy;
• The galaxy increased its parameters due to absorption and merger with others. It is now taking stars from the Sagittarius Dwarf Galaxy and the Magellanic Clouds;
• The Milky Way moves through space with an acceleration of 550 km/s relative to the cosmic microwave background radiation;
• The supermassive black hole Sagittarius A* lurks at the galactic center. Its mass is 4.3 million times greater than that of the Sun;
• Gas, dust and stars rotate around the center at a speed of 220 km/s. This is a stable indicator, implying the presence of a dark matter shell;
• In 5 billion years, a collision with the Andromeda Galaxy is expected.

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 with its planets, including the Earth, belongs. 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 saw for the first time 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.

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. "gas ring" The gas ring contains billions of solar masses of gas and dust and is a site of active star formation. This area emits strongly in the radio and infrared range. The study of this formation was carried out using clouds of gas and dust located along the line of sight, and therefore measuring the exact distances to this formation, as well as its exact configuration, is very difficult and there are still two main opinions of scientists on this matter. According to the first, scientists believe that this formation is not a ring, but grouped spirals. According to another opinion, this formation can be considered ring-shaped. Presumably it is located at a distance between 10 and 16 thousand light years from the center.

There is a special branch of astrophysics that studies the movement of stars in the Milky Way, it is called “stellar kinematics”.

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 is on average 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!

In our age, illuminated by hundreds of electric lights, city residents have no opportunity to see the Milky Way. This phenomenon, which appears in our sky only during a certain period of the year, is observed only far from large populated areas. In our latitudes it is especially beautiful in August. In the last month of summer, the Milky Way rises above the Earth in the form of a giant celestial arch. This weak, blurry strip of light appears denser and brighter in the direction of Scorpio and Sagittarius, and paler and more diffuse near Perseus.

Star Riddle

The Milky Way is an unusual phenomenon, the secret of which has not been revealed to people for a whole string of centuries. In the legends and myths of many peoples it was called differently. The amazing glow was the mysterious Star Bridge leading to heaven, the Road of the Gods and the magical Heavenly River carrying divine milk. At the same time, all peoples believed that the Milky Way was something sacred. The radiance was worshiped. Even temples were built in his honor.

Few people know that our New Year tree is an echo of the cults of people who lived in former times. Indeed, in ancient times it was believed that the Milky Way was the axis of the Universe or the World Tree, on whose branches stars ripened. That is why at the beginning of the annual cycle they decorated the Christmas tree. The earthly tree was an imitation of the eternally fruitful tree of heaven. Such a ritual gave hope for the favor of the gods and a good harvest. So great was the importance of the Milky Way for our ancestors.

Scientific assumptions

What is the Milky Way? The history of the discovery of this phenomenon goes back almost 2000 years. Plato also called this strip of light a seam connecting the celestial hemispheres. In contrast to this, Anaxagoras and Demoxide argued that the Milky Way (we’ll look at what color it is) is a kind of illumination of stars. She is the decoration of the night sky. Aristotle explained that the Milky Way is the glow of luminous lunar vapors in the air of our planet.

There were many other assumptions. Thus, the Roman Marcus Manilius said that the Milky Way is a constellation of small celestial bodies. It was he who was closest to the truth, but he could not confirm his assumptions in those days when the sky was observed only with the naked eye. All ancient researchers believed that the Milky Way was part of the solar system.

Galileo's discovery

The Milky Way revealed its secret only in 1610. It was then that the first telescope was invented, which was used by Galileo Galilei. The famous scientist saw through the device that the Milky Way was a real cluster of stars, which, when viewed with the naked eye, merged into a continuous, faintly flickering strip. Galileo even managed to explain the heterogeneity of the structure of this band.

It was caused by the presence of not only star clusters in the celestial phenomenon. There are also dark clouds there. The combination of these two elements creates an amazing image of a night phenomenon.

William Herschel's discovery

The study of the Milky Way continued into the 18th century. During this period, its most active researcher was William Herschel. The famous composer and musician was engaged in the manufacture of telescopes and studied the science of stars. Herschel's most important discovery was the Great Plan of the Universe. This scientist observed the planets through a telescope and counted them in different parts of the sky. Research has led to the conclusion that the Milky Way is a kind of star island in which our Sun is located. Herschel even drew a schematic plan of his discovery. In the picture, the star system was depicted in the form of a millstone and had an elongated irregular shape. At the same time, the sun was inside this ring that surrounded our world. This is exactly how all scientists imagined our Galaxy until the beginning of the last century.

It was only in the 1920s that the work of Jacobus Kaptein was published, in which the Milky Way was described in the most detail. At the same time, the author gave a diagram of the star island, as similar as possible to the one that is currently known to us. Today we know that the Milky Way is a Galaxy that contains the Solar System, the Earth and those individual stars that are visible to humans with the naked eye.

Structure of galaxies

With the development of science, astronomical telescopes became more and more powerful. At the same time, the structure of the observed galaxies became increasingly clear. It turned out that they are not similar to each other. Some of them were incorrect. Their structure had no symmetry.

Elliptical and spiral galaxies have also been observed. What type of these types does the Milky Way belong to? This is our Galaxy, and, being inside, it is very difficult to determine its structure. However, scientists have found an answer to this question. Now we know what the Milky Way is. Its definition was given by researchers who established that it is a disk with an internal core.

general characteristics

The Milky Way is a spiral galaxy. Moreover, it has a bridge in the form of a huge interconnected gravitational force.

The Milky Way is believed to have existed for over thirteen billion years. This is the period during which about 400 billion constellations and stars, over a thousand huge gas nebulae, clusters and clouds were formed in this Galaxy.

The shape of the Milky Way is clearly visible on the map of the Universe. Upon examination, it becomes clear that this cluster of stars is a disk whose diameter is 100 thousand light years (one such light year is ten trillion kilometers). The thickness is 15 thousand, and the depth is about 8 thousand light years.

How much does the Milky Way weigh? It is not possible to calculate this (determining its mass is a very difficult task). Difficulties arise in determining the mass of dark matter, which does not interact with electromagnetic radiation. This is why astronomers cannot definitively answer this question. But there are rough calculations according to which the weight of the Galaxy ranges from 500 to 3000 billion solar masses.

The Milky Way is like all celestial bodies. It rotates around its axis, moving through the Universe. Astronomers point to the uneven, even chaotic movement of our Galaxy. This is explained by the fact that each of its constituent stellar systems and nebulae has its own speed, different from the others, as well as different shapes and types of orbits.

What parts does the Milky Way consist of? These are the core and bridges, the disc and spiral arms, and the crown. Let's take a closer look at them.

Core

This part of the Milky Way is located in the core. There is a source of non-thermal radiation with a temperature of about ten million degrees. At the center of this part of the Milky Way is a compaction called a “bulge.” This is a whole string of old stars that moves along an elongated orbit. Most of these celestial bodies are already reaching the end of their life cycle.

In the central part of the core of the Milky Way is located. This section of outer space, the weight of which is equal to the mass of three million suns, has the most powerful gravity. Another black hole rotates around it, only smaller. Such a system creates such a force that nearby constellations and stars move along very unusual trajectories.

The center of the Milky Way has other features. Thus, it is characterized by a large cluster of stars. Moreover, the distance between them is hundreds of times smaller than that observed on the periphery of the formation.

It is also interesting that, observing the nuclei of other galaxies, astronomers note their bright shine. But why is it not visible in the Milky Way? Some researchers have even suggested that there is no core in our Galaxy. However, it was determined that in spiral nebulae there are dark layers that are interstellar accumulations of dust and gas. They are also found in the Milky Way. These huge dark clouds prevent the earthly observer from seeing the glow of the core. If such a formation did not interfere with earthlings, then we could observe the core in the form of a shining ellipsoid, the size of which would exceed the diameter of one hundred moons.

Modern telescopes, which are capable of operating in special ranges of the electromagnetic spectrum of radiation, have helped people answer this question. With the help of this modern technology, which was able to bypass the dust shield, scientists were able to see the core of the Milky Way.

Jumper

This element of the Milky Way crosses its central section and has a size of 27 thousand light years. The bridge consists of 22 million red stars of impressive age. Around this formation there is a gas ring, which contains a large percentage of molecular oxygen. All this suggests that the Milky Way bar is the area where stars are formed in the greatest number.

Disk

The Milky Way itself has this shape, which is in constant rotational motion. Interestingly, the speed of this process depends on the distance of a particular area from the nucleus. So, in the very center it is equal to zero. At a distance of two thousand light years from the core, the rotation speed is 250 kilometers per hour.

The outer side of the Milky Way is surrounded by a layer of atomic hydrogen. Its thickness is 1.5 thousand light years.

On the outskirts of the Galaxy, astronomers have discovered the presence of dense gas clusters with a temperature of 10 thousand degrees. The thickness of such formations is several thousand light years.

Five spiral arms

These are another component of the Milky Way, located directly behind the gas ring. The spiral arms cross the constellations Cygnus and Perseus, Orion and Sagittarius, and Centaurus. These formations are unevenly filled with molecular gas. This composition introduces errors into the rules of rotation of the Galaxy.
The spiral arms extend directly from the core of the star island. We observe them with the naked eye, calling the light strip the Milky Way.

The spiral branches are projected onto each other, which makes it difficult to understand their structure. Scientists suggest that such arms were formed due to the presence in the Milky Way of giant waves of rarefaction and compression of interstellar gas, which move from the core to the galactic disk.

Crown

The Milky Way has a spherical halo. This is his crown. This formation consists of individual stars and clusters of constellations. Moreover, the dimensions of the spherical halo are such that it extends beyond the boundaries of the Galaxy by 50 light years.

The Milky Way's corona typically contains low-mass and old stars, as well as dwarf galaxies and hot gas clusters. All these components move in elongated orbits around the nucleus, performing random rotation.

There is a hypothesis according to which the emergence of the corona was a consequence of the absorption of small galaxies by the Milky Way. According to astronomers, the age of the halo is about twelve billion years.

Location of stars

In a cloudless night sky, the Milky Way is visible from anywhere on our planet. However, only part of the Galaxy is accessible to human eyes, which is a system of stars located inside the Orion arm.

What is the Milky Way? The definition of all its parts in space becomes most clear if we consider a star map. In this case, it becomes clear that the Sun, which illuminates the Earth, is located almost on the disk. This is almost the edge of the Galaxy, where the distance from the core is 26-28 thousand light years. Moving at a speed of 240 kilometers per hour, the Sun spends 200 million years on one revolution around the core, so during its entire existence it traveled around the disk, circling the core, only thirty times.

Our planet is located in the so-called corotation circle. This is a place where the rotation speeds of the arms and stars are identical. This circle is characterized by an increased level of radiation. That is why life, as scientists believe, could only arise on that planet near which there are a small number of stars.

Our Earth was such a planet. It is located on the periphery of the Galaxy, in its quietest place. This is why there have been no global cataclysms on our planet for several billion years, which often occur in the Universe.

Forecast for the future

Scientists suggest that in the future, collisions between the Milky Way and other galaxies are very likely, the largest of which is the Andromeda galaxy. But at the same time, it is not possible to talk specifically about anything. This requires knowledge about the magnitude of the transverse velocities of extragalactic objects, which are not yet available to modern researchers.

In September 2014, one of the models for the development of events was published in the media. According to it, four billion years will pass, and the Milky Way will absorb the Magellanic Clouds (Large and Small), and in another billion years it itself will become part of the Andromeda Nebula.

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.