What does the Milky Way galaxy look like? Milky Way galaxy: interesting facts

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).

Discovery history

Discovery of Galileo

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 is a real cluster of stars, which, when viewed with the naked eye, merged into a continuous faintly twinkling band. Galileo even succeeded in explaining the heterogeneity of the structure of this band. It was caused by the presence in the celestial phenomenon of not only star clusters. There are also dark clouds. The combination of these two elements creates an amazing image of the night phenomenon.

Discovery of William Herschel

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

It was not until the 1920s that the work of Jacobus Kaptein saw the light of day, in which the Milky Way was described in the most detailed way. At the same time, the author gave a scheme of the star island, which is as similar as possible to the one that is known to us at the present time. Today we know that the Milky Way is a Galaxy, which includes the solar system, the Earth and those individual stars that are visible to humans with the naked eye.

What shape is the Milky Way?

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 probably a spiral galaxy.

In the 1930s, R. J. Trumpler realized that the estimates of the size of the Milky Way galaxy made by Kapetin and others were erroneous, because the measurements were based on observations using radiation waves in the visible region of the spectrum. Trumpler came to the conclusion that a 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, in order to accurately image the stars and star clusters within 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. To do this, we used the marking of stars by analogy with marks when measuring distances. Astronomers realized that O and B stars could serve to achieve this goal.

Such stars have several features:

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

Astronomers can use radio telescopes to accurately match the positions of O and B stars and, based on the 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 you see when you mix cake dough with an electric mixer. These density waves are thought to have caused the spiral character of the galaxy.

Thus, by viewing the sky in waves of different wavelengths (radio, infrared, visible, ultraviolet, X-ray) using various ground-based and space telescopes, one can obtain various images of the Milky Way.

Doppler effect. Just as the high pitched sound of a fire truck siren gets lower as the vehicle moves away, the movement of the stars affects the wavelengths of light that reach Earth from them. 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 indicates how fast the star is moving relative to us. In addition, the direction of the Doppler shift can show us the direction in which the star is moving. If the star's spectrum 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 consider the structure of the Milky Way, we will see the following:

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 - areas around the nucleus, including directly the areas above and below the plane of the disk.
Spiral arms are areas that protrude outward from the center. Our solar system is located in one of the spiral arms of the Milky Way.

globular clusters. Several hundred of them are scattered above and below the plane of the disk.
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 much 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 a few thousand light-years of the center of the Galaxy is called bulge(translated from English "thickening"). The halo as a whole rotates very slowly.

Compared to halo disk spins much faster. It looks like two plates folded at the edges. The diameter of the disk of the Galaxy 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 rapidly 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 the mass of the Sun (1.99*1030 kg). Young stars and star clusters are concentrated in the disk. There are many bright and hot stars among them. The gas in the disk of the Galaxy is unevenly distributed, forming giant clouds. Hydrogen is the main chemical element in our Galaxy. About 1/4 of it consists of helium.

One of the most interesting regions of the Galaxy is its center, or nucleus located in the direction of the constellation Sagittarius. The visible radiation of the central regions of the Galaxy is completely hidden from us by powerful layers of absorbing matter. Therefore, it began to be studied only after the creation of receivers for infrared and radio radiation, which is 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, regions of ionized hydrogen and numerous sources of infrared radiation are noted, indicating star formation taking place there. At 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, the youngest stars are mainly concentrated, many open star clusters, as well as chains of dense clouds of interstellar gas in which stars continue to form. In contrast to the halo, where any manifestations of stellar activity are extremely rare, a stormy 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, which are concentrated along long spirals. According to modern concepts, spiral arms are associated with compression waves propagating across the disk of the galaxy. Passing through the compression regions, the matter of the disk becomes denser, and the formation of stars from the gas becomes more intense. The reasons for the appearance of such a peculiar wave structure in the disks of spiral galaxies are not entirely clear. Many astrophysicists are working on this problem.

The place of the sun in the galaxy

In the vicinity of the Sun, it is possible to trace sections of two spiral branches that are about 3 thousand light years away from us. According to the constellations where these areas are found, they are called the Sagittarius arm and the Perseus arm. The sun is almost in the middle between these spiral arms. True, relatively close (by galactic standards) from us, in the constellation of Orion, there is another, not so pronounced branch, which is considered an offshoot 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 edge of the disk than to its center.

Together with all nearby stars, the Sun revolves around the center of the Galaxy at a speed of 220–240 km/s, making one revolution in about 200 million years. This means that for the entire time of its existence, the Earth flew 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 compression wave, which forms the spiral arm, moves in the given region. Such a situation is generally unusual for the Galaxy: the spiral arms rotate at a constant angular velocity, like the spokes of a wheel, while the movement of stars, as we have seen, obeys a completely different pattern. Therefore, almost the entire stellar population of the disk either gets inside the spiral branch or leaves it. The only place where the speeds of stars and spiral arms coincide is the so-called corotation circle, and it is on it that the Sun is located!

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

The location of the stars

On a cloudless night sky, the Milky Way is visible from anywhere on our planet. However, only a part of the Galaxy, which is a system of stars located inside the Orion arm, is accessible to the human eye. What is the Milky Way? The definition in space of all its parts becomes most understandable if we consider the star map. In this case, it becomes clear that the Sun, illuminating the Earth, is located almost on the disk. This is almost the edge of the Galaxy, where the distance from the nucleus is 26-28 thousand light years. Moving at a speed of 240 kilometers per hour, the Luminary spends 200 million years on one revolution around the core, so that for the entire time of its existence it traveled across the disk, rounding the core, only thirty times. Our planet is in the so-called corotation circle. This is a place in which the speed of rotation 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 is a small number of stars. Our Earth is such a planet. It is located on the periphery of the Galaxy, in its most peaceful place. That is why on our planet for several billion years there were no global cataclysms that 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 can blindly look around, thinking that the Milky Way, Andromeda (our older sister) and a bunch of unknowns - our space neighbors - this is our home, but in reality there is much more. It's time to explore what else is around us. Go.

Triangulum Galaxy. With a mass of about 5% of that of the Milky Way, 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 is 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 give rise to new, hot and large stars in the universe.
Small Magellanic Cloud, NGC 3190 and NGC 6822. All of them have masses from 0.1% to 0.6% of the Milky Way (and it is not clear which one is larger) and all three are independent galaxies. Each contains over a billion solar masses of material.
Elliptical galaxies M32 and M110. They may be "only" satellites of Andromeda, but each of them has more than a billion stars, and they can even exceed the masses of numbers 5, 6 and 7.

In addition, there are at least 45 other known galaxies - smaller ones - that make up our local group. Each of them has a halo of dark matter surrounding it; each of them is gravitationally attached 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 tides, and this is partly true. But from the point of view of the galaxy, the tides are a less noticeable process. The part of the small galaxy that is close to the big one will be attracted with more gravitational force, and the part that is further away will experience less attraction. 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 incorporated into the large galaxies with which they merge. “So what,” you say. After all, this is not quite 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 drag the galaxies into a gravitational dance that will lead to a big 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: the Milkweeds.

A small percentage of the stars will be ejected during such a merger, but the majority will remain unharmed, 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 to gobble up the rest. This process will take place in all connected groups and clusters of galaxies throughout the Universe, while dark energy will push individual groups and clusters apart from each other. But even this cannot be called death, because the galaxy will remain. And for a while it will be. But the galaxy is made up of stars, dust and gas, and everything will eventually come to an end.

Across the Universe, galactic mergers will take place over tens of billions of years. During the same time, dark energy will pull them all over 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 inhabit each galaxy—albeit with 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 inevitability happens, we're left with brown dwarfs (failed stars) that accidentally fuse, re-ignite nuclear fusion, and create starlight for tens of trillions of years.

When the last star goes out tens of quadrillion years in the future, there will still be some mass left in the galaxy. So this can not 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 momentum 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 remnants 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 Mlecomeda there will be an object hundreds of millions of times more massive than our Sun.

But will it 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 that, the remains, rotating around the galactic center, will untie 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 be nothing that we once called the local group, the Milky Way and other dear names.

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 a 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’s road”). The myth about scattered straw is also spoken of by Arabic, Jewish, Persian, Turkish and Kyrgyz names (Kirg. samanchynyn jolu- the path of the strawman) of this phenomenon. The inhabitants of Wallachia believed that Venus stole this straw from St. Peter.

Buryat

According to Buryat mythology, good forces create the world, modify the universe. Thus, the Milky Way arose from the milk that Manzan Gurme drew from her breast and splashed out after Abai Geser, who had deceived her. According to another version, the Milky Way is a "seam of the sky" sewn up after the stars fell out of it; on it, like on a bridge, tengri walk.

Hungarian

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

ancient greek

Etymology of the word Galaxias (Γαλαξίας) and its association with milk (γάλα) reveal two similar ancient Greek myths. One of the legends tells about the mother's milk spilled across the sky of the goddess Hera, who was breastfeeding Hercules. When Hera learned that the baby she was breastfeeding 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 is the milk of Rhea, the wife of Kronos, and Zeus himself was the baby. Kronos devoured his children, as it was predicted to him that he would be overthrown by his own son. Rhea has a plan to save her sixth child, the 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 chest on a bare rock was subsequently called the Milky Way.

Indian

The ancient Indians considered the Milky Way to be the milk of an evening red cow passing through the sky. In the Rig Veda, the Milky Way is called Aryaman's Throne Road. 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 is reflected in their mythology) in the sky were the dark sections of the Milky Way - a kind of "constellation" in the terminology of Andean cultures: Lama, Lama Cub, Shepherd, Condor, Partridge, Toad, Snake, Fox; as well as the stars: the Southern Cross, the Pleiades, Lyra and many others.

Ketskaya

In the Ket myths, similarly to the Selkup ones, the Milky Way is described as the road of one of the 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 Dokh, who climbed this road to the sun.

Chinese, Vietnamese, Korean, Japanese

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

Indigenous peoples of North America

The Hidatsa and the Eskimos call the Milky Way "Ash". Their myths speak 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 dirt and silt raised by the belly of a turtle floating in the sky. Eskimos from the Bering Strait - that these are the traces of the Creator Raven walking across the sky. The Cherokee believed that the Milky Way was formed when one hunter stole another's wife out of jealousy, and her dog began to eat unattended cornmeal and scattered it across the sky (the same myth is found among the Khoisan population of the Kalahari). Another myth of the same people says that the Milky Way is the trail of a dog dragging something across the sky. The Ctunah called the Milky Way "the dog's tail", 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 to be the Tama-rereti boat. The nose 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 already late, and he was far from home. There were no stars in the sky, and, fearing that Tanif might attack, Tama-rereti began to throw sparkling pebbles into the sky. The heavenly deity Ranginui liked what he was doing, and he placed the Tama-rereti boat in the sky, and turned the pebbles into stars.

Finnish, Lithuanian, Estonian, Erzya, Kazakh

The Finnish name is Fin. Linnunrata- means "The Way of the Birds"; the Lithuanian name has a similar etymology. Estonian myth also connects the Milky ("bird's") Way with bird flight.

The Erzya name is "Kargon Ki" ("Crane Road").

The Kazakh name is “Kus Zholy” (“Way 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 that continue to exist. These are the oldest stars in the galaxy;
The galaxy has increased its parameters by absorbing and merging with others. Now she is picking stars from the Sagittarius Dwarf Galaxy and the Magellanic Clouds;
The Milky Way moves in space with an acceleration of 550 km / s with respect to the background radiation;
Lurking at the galactic center is the supermassive black hole Sagittarius A*. By mass, it is 4.3 million times greater than the solar one;
Gas, dust and stars revolve around the center at a speed of 220 km/s. This is a stable indicator, implying the presence of a shell of dark matter;
In 5 billion years, a collision with the Andromeda galaxy is expected.

Milky Way- a galaxy that is the most important for man, because it is his home. But when it comes to exploration, our galaxy becomes an unremarkable average spiral galaxy, like the billions of other galaxies scattered throughout the universe.

Looking up at the night sky, outside the city light, one can clearly see a wide bright band running across the sky. The ancient inhabitants of the Earth called this bright object, which was formed long before the formation of the Earth - a river, a road and other names similar in meaning. In reality, this is nothing more than the center of our galaxy, visible from one of its arms.

The structure of the Milky Way galaxy

The Milky Way is a barred spiral galaxy about 100,000 light-years across. If we were to look down on it, we could see a central bulge surrounded by four large spiral arms that wrap around the central region. Spiral galaxies are the most common and make up about two-thirds of all galaxies known to mankind.

Unlike an ordinary spiral, a barred spiral galaxy contains a kind of "bridge" running through its central region and two main spirals. In addition, there are a couple of sleeves in the inner part, which, at a certain distance, turn into a four-arm structure. In one of the small arms known as the arm of Orion, which is located between the large arms of Perseus and Sagittarius, our solar system is located.

The Milky Way does not stand still. It constantly revolves around its center. Thus, the sleeves are constantly moving in space. Our solar system, along with the Orion arm, is moving at about 828,000 kilometers per hour. Even moving at such a tremendous speed, the solar system will take about 230 million years to complete one revolution around the Milky Way.

Interesting facts about the Milky Way galaxy

The history of the Milky Way galaxy begins shortly after the Big Bang;
The Milky Way contains some of the earliest stars in the universe;
The Milky Way has annexed other galaxies in the distant past. Our galaxy is currently growing in size by pulling in material from the Magellanic Clouds;
The Milky Way moves through space at a speed of 552 kilometers per second;
At the center of the Milky Way is a supermassive black hole called Sgr A* with a mass of about 4.3 million solar masses;
The stars, gas and dust of the Milky Way move around the center at a speed of about 220 kilometers per second. The constancy of this speed for all stars, regardless of their distance from the core of the galaxy, speaks of the existence of mysterious dark matter;

Curved around the center of the galaxy, the spiral arms contain a large amount of dust and gas, from which new stars are subsequently formed. These arms form what astronomers call the disk of a galaxy. Its thickness compared to the diameter of the galaxy is small and is about 1000 light years.

At the center of the Milky Way is the core of the galaxy. It is filled with dust, gas and stars. The core of the Milky Way is the reason why we only see a small fraction of all the stars in our galaxy. The dust and gas in it is so dense that scientists are simply not able to see what is in the center.

Recent research by scientists confirms the fact that there is a supergiant black hole at the center of the Milky Way, the mass of which is comparable to that of ~4.3 million solar masses. At the very beginning of history, this supermassive black hole could have been much smaller, but large reserves of dust and gas allowed it to grow to such a huge size.

Although black holes cannot be detected by direct observation, astronomers can see them due to gravitational effects. According to scientists, most galaxies in the universe contain a supermassive black hole at their center.

The central core and spiral arms are not the only constituent elements of the Milky Way spiral galaxy. Our galaxy is surrounded by a spherical halo of hot gas, old stars and globular clusters. Although the halo spans hundreds of thousands of light-years, it contains about 2 percent more stars than those in the galaxy's disk.

Dust, gas and stars are the most "visible" components of our galaxy, but the Milky Way contains another yet elusive component - dark matter. Astronomers cannot yet directly detect it, but they can speak of its presence, as in the case of black holes, through indirect signs. Recent research in this area shows that 90% of the mass of our galaxy is elusive dark matter.

The future of the Milky Way galaxy

The Milky Way not only revolves around itself, but also moves in the Universe. Despite the fact that space is a relatively empty place, dust, gas and other galaxies can be encountered along the way. Our galaxy is also not immune from an accidental encounter with another massive cluster of stars.

In about 4 billion years, the Milky Way will collide with its nearest neighbor, the Andromeda Galaxy. Both galaxies are rushing towards each other at a speed of about 112 km/s. After the collision, both galaxies will provide new influx of stellar material, which will lead to a new wave of star formation.

Fortunately, the inhabitants of the Earth do not worry much about this fact. By that time, our Sun will turn into a red giant and life on our planet will be impossible.

Useful articles that will answer most of the interesting questions about the Milky Way galaxy.

deep sky objects

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 opens up to our eyes: only in the Milky Way Galaxy there are more than two hundred billion heavenly bodies (scientists have the opportunity to observe only two billion).

The Milky Way is a barred spiral galaxy, which is a huge star system gravitationally bound in space. Together with 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 were formed in it. If you look at a map of the Universe, you can see that the Milky Way is represented 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 degree of kilometers) and an average thickness of about a thousand light years (in one light year, almost 10 trillion kilometers).

How much exactly the Galaxy weighs, astronomers find it difficult to answer, since most of the weight is contained not in the constellations, as previously thought, but in dark matter, which does not emit and does not 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 turns around its axis and moves in the universe. It should be borne in mind that when moving, galaxies constantly collide with each other in space and the one that is larger absorbs the smaller ones, but if their sizes are the same, active star formation begins after the collision.

So, astronomers put forward the assumption 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 in space unevenly and even chaotically, since each star system, cloud or nebula located in it has its own speed and orbits of different types and shapes.

Structure of the Galaxy

If you look closely at a map of space, you can see that the Milky Way is very compressed in a 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.

Nucleus

The core is located in the constellation Sagittarius, where a source of non-thermal radiation is located, the temperature of which is about ten million degrees - a phenomenon that is characteristic only for the nuclei of Galaxies. In the center of the core there is a seal - 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 here an area measuring 12 by 12 parsecs, consisting of dead and dying constellations.

At the very center of the nucleus is a supermassive black hole (a section 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 have 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

A 27,000 light-year bridge crosses the central part of the Galaxy at an angle of 44 degrees to the imaginary 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 gaseous ring, which contains most of the molecular hydrogen, and therefore is the region where stars are formed in the largest number. According to one theory, such active star formation occurs in the bar due to the fact that it passes through itself the gas from which constellations are born.

Disk

The Milky Way is a disk consisting of constellations, gaseous 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 not the same and chaotic (ranges from zero in the core to 250 km / h at a distance of 2 thousand light years from it). Near the plane of the disk, gas clouds are concentrated, as well as young stars and constellations.

On the outer side of the Milky Way are layers of atomic hydrogen, which goes into space for one and a half thousand light-years from the extreme spirals. Despite the fact that this hydrogen is ten times thicker than in the center of the Galaxy, its density is just as much lower. On the outskirts of the Milky Way, dense accumulations of gas with a temperature of 10 thousand degrees were discovered, the dimensions of which exceed several thousand light years.

spiral arms

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 Centaurus (the Sun is located on the inner side of the Orion arm). Molecular gas is located in the arms unevenly and by no means always obeys the rules of rotation of the Galaxy, introducing errors.

Crown

The corona of the Milky Way is represented as a spherical halo that extends beyond the Galaxy into space for five to ten light years. The corona consists of globular clusters, constellations, individual stars (mostly old and low-mass), dwarf galaxies, hot gas. All of them move around the core in elongated orbits, while the rotation of some stars is so random that even the speed of nearby luminaries can differ significantly, so the crown rotates extremely slowly.

According to one hypothesis, the corona arose as a result of the absorption of smaller galaxies by the Milky Way, and therefore is their remnants. According to preliminary data, the age of the halo exceeds twelve billion years and it is the same age as the Milky Way, and therefore star formation has already been completed here.

starry 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 lightish stripe (since our star system is located inside the Orion arm, only part of the Galaxy is available for viewing).

The map of the Milky Way shows that our Luminary 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. Given that the Sun moves at a speed of about 240 km / h, in order to make one revolution, it needs to spend about 200 million years (for the entire period of its existence, our star has not circled the Galaxy even 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 the 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.

It is this fact that applies to our Earth. Being on the periphery, it is located in a rather calm place in the Galaxy, and therefore for several billion years it has hardly been subjected to global cataclysms, which the Universe is so rich in. Perhaps this is one of the main reasons that life was able to originate and survive on our planet.

The solar system is immersed in a huge star system - the Galaxy, numbering hundreds of billions of stars of the most different luminosity and color (Stars in the section: "The Life of Stars"). The properties of different types of stars in the Galaxy are well known to astronomers. Our neighbors are not just typical stars and other celestial objects, but rather representatives of the most numerous "tribes" of the Galaxy. At present, all or almost all stars have been studied in the vicinity of the Sun, with the exception of very dwarf ones, which emit very little light. Most of them are very faint red dwarfs - their masses are 3-10 times less than that of the Sun. Stars similar to the Sun are very rare, only 6% of them. Many of our neighbors (72%) are grouped into multiple systems, where the components are connected to each other by gravitational forces. Which of the hundreds of nearby stars can claim the title of the nearest neighbor of the Sun? Now it is considered a component of the well-known triple system Alpha Centauri - the faint red dwarf Proxima. The distance to the proxima is 1.31 pc, the light from it takes 4.2 years to reach us. The statistics of the circumsolar population gives an idea of the evolution of the galactic disk and the galaxy as a whole. For example, the luminosity distribution of solar-type stars shows that the age of the disk is 10-13 billion years.

In the 17th century, after the invention of the telescope, scientists first realized how large the number of stars in outer space is. In 1755, the German philosopher and naturalist Immanuel Kant suggested that the stars form groups in space, just as the planets make up the solar system. These groups he called "star islands". According to Kant, one of these innumerable islands is the Milky Way - a grandiose cluster of stars visible in the sky as a bright foggy band. In ancient Greek, the word "galactikos" means "milky", which is why the Milky Way and similar star systems are called galaxies.

Dimensions and structure of our Galaxy

Based on the results of his calculations, Herschel made an attempt to determine the dimensions and forms a kind of thick disk: in the plane of the Milky Way, it extends to a distance of no more than 850 units, and in the perpendicular direction - 200 units, if we take the distance to Sirius as a unit. According to the modern scale of distances, this corresponds to 7300X1700 light years. This estimate generally correctly reflects the structure of the Milky Way, although it is highly inaccurate. The fact is that in addition to stars, the disk of the Galaxy also includes numerous gas and dust clouds, which weaken the light of distant stars. The first explorers of the Galaxy did not know about this absorbing substance and believed that they could see all its stars.

The true dimensions of the Galaxy were established only in the 20th century. It turned out that it is a much flatter formation than previously thought. The diameter of the galactic disk exceeds 100 thousand light years, and the thickness is about 1000 light years. Due to the fact that the Solar System is located practically in the plane of the Galaxy, filled with absorbing matter, many details of the structure of the Milky Way are hidden from the gaze of an earthly observer. However, they can be studied on the example of other galaxies similar to Shashi. So, in the 40s. XX century, observing the galaxy M 31, better known as the Andromeda Nebula, the German astronomer Walter Baade noticed that the flat lenticular disk of this huge galaxy is immersed in a more rarefied spherical star cloud - a halo. Since the nebula is very similar to our Galaxy, he suggested that the Milky Way also has a similar structure. The stars of the galactic disk have been called population type I, while the stars in the halo have been called population type II.

As modern studies show, the two types of stellar population differ not only in their spatial position, but also in the nature of their movement, as well as in their chemical composition. These features are associated primarily with the different origin of the disk and the spherical component.

Structure of the Galaxy: Halo

The boundaries of our Galaxy are determined by the size of the halo. The radius of the halo is much 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, low-mass stars. They occur both singly and in the form of globular clusters, which can include more than a million stars. The age of the population of the spherical component of the Galaxy exceeds 12 billion years. It is usually taken as the age of the Galaxy itself. A characteristic feature of halo stars is their extremely small proportion of heavy chemical elements. The stars that form globular clusters contain hundreds of times less metals than the Sun.

The stars of the spherical component are concentrated towards the center of the Galaxy. The central, densest part of the halo within a few thousand light-years from the center of the Galaxy is called the "bulge" ("thickening"). Stars and stellar halo clusters move around the center of the Galaxy in very elongated orbits. Due to the fact that the rotation of individual stars occurs almost randomly, the halo as a whole rotates very slowly.

Structure of the Galaxy: Disk

Compared to the halo, the disk rotates noticeably faster. The speed of its rotation is not the same at different distances from the center. It rapidly increases from zero in the center to 200-240 km/s at a distance of 2 thousand light years from it, then decreases somewhat, increases again to approximately the same value, and then remains almost constant. The study of the features of disk rotation made it possible to estimate its mass. It turned out that it is 150 billion times more than the mass of the Sun. The disk population is very different from the halo population. Near the plane of the disk, young stars and star clusters are concentrated, the age of which does not exceed several billion years. They form the so-called flat component. There are a lot of bright and hot stars among them.

The gas in the disk of the Galaxy is also concentrated mainly near its plane. It is located unevenly, forming numerous gas clouds - giant heterogeneous superclouds with a length of several thousand light-years to small clouds no larger than a parsec in size. Hydrogen is the main chemical element in our Galaxy. Approximately 1/4 of it consists of helium. Compared to these two elements, the rest are present in very small amounts. On average, the chemical composition of stars and gas in the disk is almost the same as that of the Sun.

Structure of the Galaxy: Core

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 of the central regions of the Galaxy is completely hidden from us by powerful layers of absorbing matter. Therefore, they began to study it only after the creation of receivers for infrared and radio radiation, which is absorbed to a lesser extent. The central regions of the Galaxy are characterized by a strong concentration of stars: each cubic parsec near the center contains many thousands of them. Distances between stars are tens and hundreds of times less than in the vicinity of the Sun. If we lived on a planet near a star located near the core of the Galaxy, then dozens of stars would be visible in the sky, comparable in brightness to the Moon, and many thousands brighter than the brightest stars in our sky.

In addition to a large number of stars in the central region of the Galaxy, there is a circumnuclear gaseous disk, consisting mainly of molecular hydrogen. Its radius exceeds 1000 light years. Closer to the center, regions of ionized hydrogen and numerous sources of infrared radiation are noted, indicating star formation taking place 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. In the center there is also a bright radio source Sagittarius A, the origin of which is associated with the activity of the nucleus.

Hello dear guys! And I welcome you, dear parents! I suggest you go on a little journey into the outer world, full of the unknown and bewitching.

How often do we look into a dark sky full of bright stars, trying to find the constellations discovered by astronomers. Have you ever seen the Milky Way in the sky? Let's take a closer look at this unique cosmic phenomenon. And at the same time we will get information for an informative and interesting "space" project.

Lesson plan:

Why is it called that?

This starry path in the sky looks like a white stripe. Ancient people explained this phenomenon seen in the starry night sky with the help of mythological stories. Different peoples had their own versions of the appearance of an unusual celestial band.

The most common is the hypothesis of the ancient Greeks, according to which the Milky Way is nothing but the spilled mother's milk of the Greek goddess Hera. So explanatory dictionaries interpret the adjective "milky" as "resembling milk."

There is even a song about it, you must have heard it at least once. And if not, then listen right now.

Because of the way the Milky Way looks like, it has several names:

the Chinese call it the "yellow road", believing that it looks more like straw;
the Buryats call the streak of stars "the seam of the sky", from which the stars scattered;
among the Hungarians, it is associated with the road of warriors;
ancient Indians considered it to be the milk of an evening red cow.

How to see the "milk path"?

Of course, this is no milk that someone spills every day across the night sky. The Milky Way is a giant star system called the "Galaxy". In its appearance, it looks like a spiral, in the center of which there is a nucleus, and from it, like rays, arms extend, of which the Galaxy has four.

How to find this white path of stars? You can even see a star cluster with the naked eye in the night sky when there are no clouds. All inhabitants of the Milky Way are located on the same line.

If you are a resident of the northern hemisphere, then you can find the place where the scattering of stars is located at midnight in July. In August, when it gets dark earlier, it will be possible to search for the spiral of the Galaxy, starting already from ten in the evening, and in September - after 20.00. You can see all the beauty by first finding the constellation Cygnus and moving from it with a look to the north - northeast.

To see the brightest stellar segments, you need to go to the equator, and even better - closer to 20-40 degrees south latitude. It is there that in late April - early May, the Southern Cross and Sirius flaunt in the night sky, between which the cherished galactic star path passes.

When the constellations of Sagittarius and Scorpio rise in the eastern part by June-July, the Milky Way is gaining special brightness, and clouds of cosmic dust can even be seen between distant stars.

Seeing various photographs, many are wondering: why do we see not a spiral, but only a strip? The answer to this question is very simple: we are inside the Galaxy! If we stand in the center of a sports hoop and raise it at eye level, what will we see? That's right: a strip before the eyes!

The nucleus of the Galaxy can be found in the constellation Sagittarius with the help of radio telescopes. Only now you should not expect special brightness from him. The central part is the darkest due to the large amount of cosmic dust in it.

What is the Milky Way made of?

Our Galaxy is just one of the millions of star systems that have been found by astronomers, but it's quite a big one. The Milky Way contains approximately 300 billion stars. The Sun, which rises every day in the sky, is also part of them, revolving around the core. The Galaxy has stars much larger and brighter than the Sun, there are smaller ones that emit weak light.

They differ not only in size, but also in color - they can be white and blue (they are the hottest) and red (the coldest). All of them move together in a circle along with the planets. Just imagine that we go through a complete revolution in the galactic circle in almost 250 million years - that's how long one galactic year lasts.

Stars live on the strip of the Milky Way, forming groups that scientists call clusters, differing in age and stellar composition.

Small open clusters are the youngest, only about 10 million years old, but it is there that massive and bright celestial representatives live. Such groups of stars are located along the edge of the plane.
Globular clusters are very old, they formed over 10-15 billion years, they are located in the center.

10 interesting facts

As always, I advise you to decorate your research work with the most interesting "galactic" facts. Watch the video carefully and be amazed!

This is how it is, our Galaxy, in which we live in the midst of wonderful bright neighbors. If you are not personally familiar with the "milk path" yet, then rather go outside to see all the starry beauty in the night sky.

By the way, have you already read the article about our space neighbor the Moon? Not yet? Then take a look)

Success in your studies!

Evgenia Klimkovich.