The Milky Way is our galaxy. Milky Way

Our Galaxy. Mysteries of the Milky Way

To some extent, we know more about distant star systems than about our home Galaxy - the Milky Way. It is more difficult to study its structure than the structure of any other galaxies, because it has to be studied from the inside, and many things are not so easy to see. Interstellar dust clouds absorb the light emitted by myriads of distant stars.

Only with the development of radio astronomy and the advent of infrared telescopes were scientists able to understand how our Galaxy works. But many details remain unclear to this day. Even the number of stars in the Milky Way is estimated rather roughly. The latest electronic reference books give figures from 100 to 300 billion stars.

Not so long ago, it was believed that our Galaxy has 4 large arms. But in 2008, astronomers from the University of Wisconsin published the results of processing about 800,000 infrared images taken by the Spitzer Space Telescope. Their analysis showed that the Milky Way has only two arms. As for the other branches, they are only narrow side branches. So, the Milky Way is a spiral galaxy with two arms. It should be noted that most spiral galaxies known to us also have only two arms.

“Thanks to the Spitzer telescope, we have the opportunity to rethink the structure of the Milky Way,” said astronomer Robert Benjamin of the University of Wisconsin, speaking at a conference of the American Astronomical Society. “We are refining our understanding of the Galaxy in the same way that centuries ago, pioneers, traveling around the globe, refined and rethought previous ideas about what the Earth looks like.”

Since the early 90s of the 20th century, observations carried out in the infrared range have increasingly changed our knowledge of the structure of the Milky Way, because infrared telescopes make it possible to look through gas and dust clouds and see what is inaccessible to conventional telescopes.

2004 - The age of our Galaxy was estimated at 13.6 billion years. It arose shortly after. At first it was a diffuse gas bubble containing mainly hydrogen and helium. Over time, it turned into the huge spiral galaxy in which we now live.

general characteristics

But how did the evolution of our Galaxy proceed? How was it formed - slowly or, on the contrary, very quickly? How did it become saturated with heavy elements? How has the shape of the Milky Way and its chemical composition changed over billions of years? Scientists have yet to provide detailed answers to these questions.

The extent of our Galaxy is about 100,000 light years, and the average thickness of the galactic disk is about 3,000 light years (the thickness of its convex part, the bulge, reaches 16,000 light years). However, in 2008, Australian astronomer Brian Gensler, after analyzing the results of observations of pulsars, suggested that the galactic disk is probably twice as thick as is commonly believed.

Is our Galaxy large or small by cosmic standards? By comparison, the Andromeda nebula, our closest large galaxy, is approximately 150,000 light years across.

At the end of 2008, researchers established using radio astronomy methods that the Milky Way is rotating faster than previously thought. Judging by this indicator, its mass is approximately one and a half times higher than was commonly believed. According to various estimates, it varies from 1.0 to 1.9 trillion solar masses. Again, for comparison: the mass of the Andromeda nebula is estimated at at least 1.2 trillion solar masses.

Structure of galaxies

Black hole

So, the Milky Way is not inferior in size to the Andromeda nebula. “We should no longer think of our galaxy as the little sister of the Andromeda nebula,” said astronomer Mark Reid of the Smithsonian Center for Astrophysics at Harvard University. At the same time, since the mass of our Galaxy is greater than expected, its gravitational force is also greater, which means that the likelihood of it colliding with other galaxies in our vicinity increases.

Our Galaxy is surrounded by a spherical halo, reaching a diameter of 165,000 light years. Astronomers sometimes call the halo a “galactic atmosphere.” It contains approximately 150 globular clusters, as well as a small number of ancient stars. The rest of the halo space is filled with rarefied gas, as well as dark matter. The mass of the latter is estimated at approximately a trillion solar masses.

The spiral arms of the Milky Way contain enormous amounts of hydrogen. This is where stars continue to be born. Over time, young stars leave the arms of galaxies and “move” into the galactic disk. However, the most massive and bright stars do not live long enough, so they do not have time to move away from their place of birth. It is no coincidence that the arms of our Galaxy glow so brightly. Most of the Milky Way consists of small, not very massive stars.

The central part of the Milky Way is located in the constellation Sagittarius. This area is surrounded by dark gas and dust clouds, behind which nothing can be seen. Only since the 1950s, using radio astronomy, have scientists been able to gradually discern what lies there. In this part of the Galaxy, a powerful radio source was discovered, called Sagittarius A. As observations have shown, a mass is concentrated here that exceeds the mass of the Sun by several million times. The most acceptable explanation for this fact is only one: in the center of our Galaxy is located.

Now, for some reason, she has taken a break for herself and is not particularly active. The flow of matter here is very poor. Maybe over time the black hole will develop an appetite. Then it will again begin to absorb the veil of gas and dust that surrounds it, and the Milky Way will join the list of active galaxies. It is possible that before this, stars will begin to rapidly form in the center of the Galaxy. Similar processes are likely to be repeated regularly.

2010 - American astronomers, using the Fermi Space Telescope, designed to observe sources of gamma radiation, discovered two mysterious structures in our Galaxy - two huge bubbles emitting gamma radiation. The diameter of each of them is on average 25,000 light years. They fly away from the center of the Galaxy in northern and southern directions. Perhaps we are talking about streams of particles that were once emitted by a black hole located in the middle of the Galaxy. Other researchers believe that we are talking about gas clouds that exploded during the birth of stars.

There are several dwarf galaxies around the Milky Way. The most famous of them are the Large and Small Magellanic Clouds, which are connected to the Milky Way by a kind of hydrogen bridge, a huge plume of gas that stretches behind these galaxies. It was called the Magellanic Stream. Its extent is about 300,000 light years. Our Galaxy constantly absorbs the dwarf galaxies closest to it, in particular the Sagitarius Galaxy, which is located at a distance of 50,000 light years from the galactic center.

It remains to add that the Milky Way and the Andromeda nebula are moving towards each other. Presumably, after 3 billion years, both galaxies will merge together, forming a larger elliptical galaxy, which has already been called Milkyhoney.

Origin of the Milky Way

Andromeda's nebula

For a long time it was believed that the Milky Way formed gradually. 1962 - Olin Eggen, Donald Linden-Bell and Allan Sandage proposed a hypothesis that became known as the ELS model (named after the initial letters of their last names). According to it, a homogeneous cloud of gas once slowly rotated in place of the Milky Way. It resembled a ball and reached approximately 300,000 light years in diameter, and consisted mainly of hydrogen and helium. Under the influence of gravity, the protogalaxy shrank and became flat; at the same time, its rotation noticeably accelerated.

For almost two decades, this model suited scientists. But new observational results show that the Milky Way could not have arisen in the way theorists predicted.

According to this model, a halo forms first, and then a galactic disk. But the disk also contains very ancient stars, for example, the red giant Arcturus, whose age is more than 10 billion years, or numerous white dwarfs of the same age.

Globular clusters have been discovered in both the galactic disk and halo that are younger than the ELS model allows. Obviously, they are absorbed by our late Galaxy.

Many stars in the halo rotate in a different direction than the Milky Way. Maybe they, too, were once outside the Galaxy, but then they were drawn into this “stellar vortex” - like a random swimmer in a whirlpool.

1978 - Leonard Searle and Robert Zinn proposed their model of the formation of the Milky Way. It was designated as "Model SZ". Now the history of the Galaxy has become noticeably more complicated. Not so long ago, its youth, in the opinion of astronomers, was described as simply as in the opinion of physicists - rectilinear translational motion. The mechanics of what was happening were clearly visible: there was a homogeneous cloud; it consisted only of evenly spread gas. Nothing by its presence complicated the theorists' calculations.

Now, instead of one huge cloud in the visions of scientists, several small, intricately scattered clouds appeared at once. Stars were visible among them; however, they were located only in the halo. Inside the halo everything was seething: clouds collided; gas masses were mixed and compacted. Over time, a galactic disk was formed from this mixture. New stars began to appear in it. But this model was subsequently criticized.

It was impossible to understand what connected the halo and the galactic disk. This condensed disk and the sparse stellar shell around it had little in common. After Searle and Zinn compiled their model, it turned out that the halo rotates too slowly to form a galactic disk. Judging by the distribution of chemical elements, the latter arose from protogalactic gas. Finally, the angular momentum of the disk turned out to be 10 times higher than the halo.

The whole secret is that both models contain a grain of truth. The trouble is that they are too simple and one-sided. Both now seem to be fragments of the same recipe that created the Milky Way. Eggen and his colleagues read a few lines from this recipe, Searle and Zinn read a few others. Therefore, trying to re-imagine the history of our Galaxy, we now and then notice familiar lines that we have already read once.

Milky Way. Computer model

So it all started shortly after the Big Bang. “Today it is generally accepted that fluctuations in the density of dark matter gave rise to the first structures - the so-called dark halos. Thanks to the force of gravity, these structures did not disintegrate,” notes German astronomer Andreas Burkert, author of a new model of the birth of the Galaxy.

Dark halos became embryos - nuclei - of future galaxies. Gas accumulated around them under the influence of gravity. A homogeneous collapse occurred, as described by the ELS model. Already 500-1000 million years after the Big Bang, gas accumulations surrounding dark halos became “incubators” of stars. Small protogalaxies appeared here. The first globular clusters arose in dense clouds of gas, because stars were born here hundreds of times more often than anywhere else. Protogalaxies collided and merged with each other - this is how large galaxies were formed, including our Milky Way. Today it is surrounded by dark matter and a halo of single stars and their globular clusters, ruins of a universe more than 12 billion years old.

There were many very massive stars in the protogalaxies. Less than a few tens of millions of years passed before most of them exploded. These explosions enriched the gas clouds with heavy chemical elements. Therefore, the stars that were born in the galactic disk were not the same as in the halo - they contained hundreds of times more metals. In addition, these explosions generated powerful galactic vortices that heated the gas and swept it beyond the protogalaxies. A separation of gas masses and dark matter occurred. This was the most important stage in the formation of galaxies, not previously taken into account in any model.

At the same time, dark halos increasingly collided with each other. Moreover, the protogalaxies stretched out or disintegrated. These catastrophes are reminiscent of the chains of stars preserved in the halo of the Milky Way since the days of “youth”. By studying their location, it is possible to assess the events that took place in that era. Gradually, these stars formed a vast sphere - the halo we see. As it cooled, gas clouds penetrated inside it. Their angular momentum was conserved, so they did not collapse into one single point, but formed a rotating disk. All this happened more than 12 billion years ago. The gas was now compressed as described in the ELS model.

At this time, the “bulge” of the Milky Way is formed - its middle part, reminiscent of an ellipsoid. The bulge is made up of very old stars. It probably arose during the merger of the largest protogalaxies that held gas clouds for the longest time. In the middle of it were neutron stars and tiny black holes - relics of exploding supernovae. They merged with each other, simultaneously absorbing gas streams. Perhaps this is how the huge black hole that now resides in the center of our Galaxy was born.

The history of the Milky Way is much more chaotic than previously thought. Our native Galaxy, impressive even by cosmic standards, was formed after a series of impacts and mergers - after a series of cosmic disasters. Traces of those ancient events can still be found today.

For example, not all stars in the Milky Way revolve around the galactic center. Probably, over the billions of years of its existence, our Galaxy has “absorbed” many fellow travelers. Every tenth star in the galactic halo is less than 10 billion years old. By that time, the Milky Way had already formed. Perhaps these are the remnants of once captured dwarf galaxies. A group of English scientists from the Astronomical Institute (Cambridge), led by Gerard Gilmour, calculated that the Milky Way could apparently absorb from 40 to 60 Carina-type dwarf galaxies.

In addition, the Milky Way attracts huge masses of gas. Thus, in 1958, Dutch astronomers noticed many small spots in the halo. In fact, they turned out to be gas clouds, which consisted mainly of hydrogen atoms and were rushing towards the galactic disk.

Our Galaxy will not restrain its appetite in the future. Perhaps it will absorb the dwarf galaxies closest to us - Fornax, Carina and, probably, Sextans, and then merge with the Andromeda nebula. Around the Milky Way – this insatiable “stellar cannibal” – it will become even more deserted.

The Milky Way Galaxy contains the solar system, Earth and all the stars that are visible to the naked eye. Together with the Triangulum Galaxy, Andromeda Galaxy and dwarf galaxies and satellites, it forms the Local Group of galaxies, which is part of the Virgo Supercluster.

According to ancient legend, when Zeus decided to make his son Hercules immortal, he placed him on the breast of his wife Hera to drink milk. But the wife woke up and, seeing that she was feeding her stepchild, pushed him away. A stream of milk splashed out and turned into the Milky Way. In the Soviet astronomical school it was simply called the “Milky Way system” or “our Galaxy.” Outside Western culture, there are many names for this galaxy. The word “milky” is replaced by other epithets. The galaxy consists of about 200 billion stars. Most of them are located in the shape of a disk. Most of the Milky Way's mass is contained in a halo of dark matter.

In the 1980s, scientists proposed that the Milky Way is a barred spiral galaxy. The hypothesis was confirmed in 2005 using the Spitzer telescope. It turned out that the central bar of the galaxy is larger than previously thought. The diameter of the galactic disk is approximately 100 thousand light years. Compared to the halo, it rotates much faster. At different distances from the center its speed is not the same. Studies of the disk's rotation have helped estimate its mass, which is 150 billion more than the mass of the Sun. Near the plane of the disk, young star clusters and stars are collected, which form a flat component. Scientists suspect that many galaxies have black holes at their cores.

A large number of stars are collected in the central regions of the Milky Way Galaxy. The distance between them is much smaller than in the vicinity of the Sun. The length of the galactic bridge, according to scientists, is 27 thousand light years. It passes through the center of the Milky Way at an angle of 44 degrees ± 10 degrees to the line between the center of the galaxy and the Sun. Its components are predominantly red stars. The jumper is surrounded by a ring called the 5 kiloparsec ring. It contains a large amount of molecular hydrogen. It is also an active star-forming region in the Galaxy. If observed from the Andromeda Galaxy, the Milky Way bar would be its brightest part.

Since the Milky Way Galaxy is considered to be spiral, it has spiral arms that are located in the plane of the disk. Around the disk is a spherical corona. The solar system is located 8.5 thousand parsecs from the center of the galaxy. According to recent observations, we can say that our Galaxy has 2 arms and a couple more arms in the inner part. They transform into a four-armed structure, which is observed in the neutral hydrogen line.

The galaxy's halo has a spherical shape that extends beyond the Milky Way by 5–10 thousand light years. Its temperature is approximately 5 * 10 5 K. The halo consists of old, low-mass, dim stars. They can be found both in the form of globular clusters and individually. The bulk of the galaxy's mass is dark matter, forming a dark matter halo. Its mass is approximately 600–3000 billion solar masses. Star clusters and halo stars move around the galactic center in elongated orbits. The halo rotates very slowly.

History of the discovery of the Milky Way Galaxy

Many celestial bodies are combined into various rotating systems. Thus, the Moon revolves around the Earth, and the satellites of the major planets form their own systems. The Earth and other planets revolve around the Sun. Scientists had a completely logical question: is the Sun part of an even larger system?

William Herschel first tried to answer this question. He calculated the number of stars in different parts of the sky and found out that there is a large circle in the sky - the galactic equator, dividing the sky into two parts. Here the number of stars turned out to be greatest. The closer this or that part of the sky is located to this circle, the more stars there are on it. Ultimately, it was discovered that the Milky Way is located at the equator of the galaxy. Herschel came to the conclusion that all the stars form one star system.

Initially, it was believed that everything in the Universe is part of our galaxy. But Kant also argued that some nebulae could be separate galaxies, like the Milky Way. It was only when Edwin Hubble measured the distance to some spiral nebulae and showed that they could not be part of the Galaxy that Kant's hypothesis was proven.

Future of the Galaxy

In the future, collisions of our Galaxy with others, including Andromeda, are possible. But there are no specific predictions yet. It is believed that in 4 billion years the Milky Way will engulf the Small and Large Magellanic Clouds, and in 5 billion years it will be engulfed by the Andromeda Nebula.

Planets of the Milky Way

Despite the fact that stars are constantly born and die, their number is clearly calculated. Scientists believe that at least one planet revolves around every star. This means that there are from 100 to 200 billion planets in the Universe. The scientists who worked on this claim studied red dwarf stars. They are smaller than the Sun and make up 75% of all the stars in the Milky Way Galaxy. Particular attention was paid to the star Kepler-32, which “hosted” 5 planets.

Planets are much more difficult to detect than stars because they do not emit light. We can confidently say about the existence of a planet only when it obscures the light of a star.

There are also planets that are similar to our Earth, but there are not so many of them. There are many types of planets, such as pulsar planets, gas giants, brown dwarfs... If the planet is made of rocks, it will not look much like Earth.

Recent studies claim that there are from 11 to 40 billion Earth-like planets in the galaxy. Scientists examined 42 stars similar to the Sun and discovered 603 exoplanets, 10 of which met the search criteria. It has been proven that all planets similar to Earth can maintain the necessary temperature for the existence of liquid water, which, in turn, will help the emergence of life.

Near the outer edge of the Milky Way, stars have been discovered that move in a special way. They drift at the edge. Scientists suggest that this is all that remains of the galaxies that were swallowed up by the Milky Way. Their encounter happened many years ago.

Galaxy satellites

As we have already said, the Milky Way Galaxy is spiral. It is a spiral of imperfect shape. For many years, scientists could not find an explanation for the galaxy's bulge. Now everyone has come to the conclusion that this is due to satellite galaxies and dark matter. They are very small and cannot influence the Milky Way. But when dark matter moves through the Magellanic Clouds, waves are created. They influence gravitational attractions. Under this action, hydrogen evaporates from the galactic center. Clouds orbit the Milky Way.

Although the Milky Way is called unique in many respects, it is not very rare. If we take into account the fact that there are approximately 170 billion galaxies in the field of view, we can argue about the existence of galaxies similar to ours. In 2012, astronomers found an exact copy of the Milky Way. It even has two moons that correspond to the Magellanic Clouds. By the way, it is assumed that in a couple of billion years they will dissolve. Finding such a galaxy was an incredible success. It was named NGC 1073. It is so similar to the Milky Way that astronomers are studying it to learn more about our galaxy.

Galactic year

An Earth year is the time it takes for the planet to make a full revolution around the Sun. In the same way, the solar system revolves around a black hole, which is located at the center of the galaxy. Its full revolution is 250 million years. When the Solar System is described, it is rarely mentioned that it moves through space, like everything else in the world. Its speed is 792,000 km per hour relative to the center of the Milky Way Galaxy. If we compare, we, moving at a similar speed, could go around the whole world in 3 minutes. A galactic year is the time it takes for the Sun to complete one revolution around the Milky Way. At last count, the sun lived for 18 galactic years.

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. 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 motion 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 Incan 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 Galaxy is very majestic and beautiful. This huge world is our Motherland, our Solar system. All the stars and other objects that are visible to the naked eye in the night sky are our galaxy. Although there are some objects that are located in the Andromeda Nebula, a neighbor of our Milky Way.

Description of the Milky Way

The Milky Way Galaxy is huge, 100 thousand light years in size, and, as you know, one light year is equal to 9460730472580 km. Our solar system is located 27,000 light years from the center of the galaxy, in one of the arms called the Orion arm.

Our solar system orbits the center of the Milky Way galaxy. This happens in the same way as the Earth rotates around the Sun. The solar system completes a revolution every 200 million years.

Deformation

The Milky Way Galaxy appears as a disk with a bulge in the center. It's not the perfect shape. On one side there is a bend north of the center of the galaxy, and on the other it goes down, then turns to the right. Outwardly, this deformation somewhat resembles a wave. The disk itself is deformed. This is due to the presence of the Small and Large Magellanic Clouds nearby. They rotate around the Milky Way very quickly - this was confirmed by the Hubble telescope. These two dwarf galaxies are often called satellites of the Milky Way. The clouds create a gravitationally bound system that is very heavy and quite massive due to the heavy elements in the mass. It is assumed that they seem to be in a tug-of-war between galaxies, creating vibrations. As a result, the Milky Way galaxy is deformed. The structure of our galaxy is special; it has a halo.

Scientists believe that in billions of years the Milky Way will absorb the Magellanic Clouds, and after some time it will be absorbed by Andromeda.

Halo

Wondering what kind of galaxy the Milky Way is, scientists began to study it. They managed to find out that 90% of its mass consists of dark matter, which is why a mysterious halo appears. Everything that is visible to the naked eye from Earth, namely that luminous matter, is approximately 10% of the galaxy.

Numerous studies have confirmed that the Milky Way has a halo. Scientists have compiled various models that take into account the invisible part and without it. After experiments, it was suggested that if there were no halo, then the speed of movement of the planets and other elements of the Milky Way would be less than now. Because of this feature, it was assumed that most of the components consist of invisible mass or dark matter.

Number of stars

The Milky Way galaxy is considered one of the most unique. The structure of our galaxy is unusual; there are more than 400 billion stars in it. About a quarter of them are large stars. Note: other galaxies have fewer stars. There are about ten billion stars in the Cloud, some others consist of a billion, and in the Milky Way there are more than 400 billion different stars, and only a small part, about 3000, is visible from Earth. It is impossible to say exactly how many stars are contained in the Milky Way, so how the galaxy is constantly losing objects due to them going supernova.

Gases and dust

Approximately 15% of the galaxy is dust and gases. Maybe because of them our galaxy is called the Milky Way? Despite its enormous size, we can see about 6,000 light years ahead, but the size of the galaxy is 120,000 light years. It may be larger, but even the most powerful telescopes cannot see beyond that. This is due to the accumulation of gas and dust.

The thickness of the dust does not allow visible light to pass through, but infrared light passes through, allowing scientists to create star maps.

What happened before

According to scientists, our galaxy has not always been like this. The Milky Way was created by the merger of several other galaxies. This giant captured other planets and areas, which had a strong impact on the size and shape. Even now, planets are being captured by the Milky Way galaxy. An example of this is the objects of Canis Major, a dwarf galaxy located near our Milky Way. Canis stars are periodically added to our universe, and from ours they move to other galaxies, for example, objects are exchanged with the Sagittarius galaxy.

View of the Milky Way

Not a single scientist or astronomer can say exactly what our Milky Way looks like from above. This is due to the fact that Earth is located in the Milky Way galaxy, 26,000 light years from the center. Because of this location, it is not possible to take pictures of the entire Milky Way. Therefore, any image of a galaxy is either pictures of other visible galaxies or someone's imagination. And we can only guess what she really looks like. There is even a possibility that we now know as much about it as the ancient people who believed the Earth to be flat.

Center

The center of the Milky Way galaxy is called Sagittarius A* - a great source of radio waves, suggesting that there is a huge black hole at its very heart. According to assumptions, its size is a little more than 22 million kilometers, and this is the hole itself.

All the substances that try to get into the hole form a huge disk, almost 5 million times larger than our Sun. But even this retraction force does not prevent new stars from forming at the edge of the black hole.

Age

Based on estimates of the composition of the Milky Way galaxy, it was possible to establish an estimated age of about 14 billion years. The oldest star is just over 13 billion years old. The age of a galaxy is calculated by determining the age of the oldest star and the phases preceding its formation. Based on the available data, scientists have suggested that our universe is about 13.6-13.8 billion years old.

First, the bulge of the Milky Way was formed, then its middle part, in the place of which a black hole subsequently formed. Three billion years later, a disk with sleeves appeared. Gradually it changed, and only about ten billion years ago it began to look the way it does now.

We are part of something bigger

All the stars in the Milky Way galaxy are part of a larger galactic structure. We are part of the Virgo Supercluster. The closest galaxies to the Milky Way, such as the Magellanic Cloud, Andromeda and other fifty galaxies, are one cluster, the Virgo Supercluster. A supercluster is a group of galaxies that occupies a huge area. And this is only a small part of the stellar surroundings.

The Virgo Supercluster contains more than a hundred groups of clusters over an area more than 110 million light-years in diameter. The Virgo cluster itself is a small part of the Laniakea supercluster, and it, in turn, is part of the Pisces-Cetus complex.

Rotation

Our Earth moves around the Sun, making a full revolution in 1 year. Our Sun orbits in the Milky Way around the center of the galaxy. Our galaxy moves in relation to a special radiation. CMB radiation is a convenient reference point that allows you to determine the speed of a wide variety of matters in the Universe. Studies have shown that our galaxy rotates at a speed of 600 kilometers per second.

Appearance of the name

The galaxy got its name because of its special appearance, reminiscent of spilled milk in the night sky. The name was given to it back in Ancient Rome. Back then it was called the “milk road.” To this day it is called the Milky Way, associating the name with the appearance of a white stripe in the night sky, with spilled milk.

References to the galaxy have been found since the era of Aristotle, who said that the Milky Way is the place where the celestial spheres contact the terrestrial ones. Until the telescope was created, no one added anything to this opinion. And only from the seventeenth century people began to look at the world differently.

Our neighbours

For some reason, many people think that the closest galaxy to the Milky Way is Andromeda. But this opinion is not entirely correct. Our closest “neighbor” is the Canis Major galaxy, located inside the Milky Way. It is located at a distance of 25,000 light years from us, and 42,000 light years from the center. In fact, we are closer to Canis Major than to the black hole at the center of the galaxy.

Before the discovery of Canis Major at a distance of 70 thousand light years, Sagittarius was considered the closest neighbor, and after that the Large Magellanic Cloud. Unusual stars with enormous class M densities were discovered in Canis.

According to the theory, the Milky Way swallowed Canis Major along with all its stars, planets and other objects.

Collision of galaxies

Recently, information has become increasingly common that the closest galaxy to the Milky Way, the Andromeda Nebula, will swallow our universe. These two giants formed at about the same time - about 13.6 billion years ago. It is believed that these giants are capable of uniting galaxies, but due to the expansion of the Universe they should move away from each other. But, contrary to all the rules, these objects are moving towards each other. The speed of movement is 200 kilometers per second. It is estimated that in 2-3 billion years Andromeda will collide with the Milky Way.

Astronomer J. Dubinsky created a model of the collision shown in this video:

The collision will not lead to a catastrophe on a global scale. And after several billion years, a new system will be formed, with the usual galactic forms.

Lost galaxies

Scientists conducted a large-scale study of the starry sky, covering approximately an eighth of it. As a result of an analysis of the star systems of the Milky Way galaxy, it was possible to find out that there are previously unknown streams of stars on the outskirts of our universe. This is all that remains of small galaxies that were once destroyed by gravity.

The telescope installed in Chile took a huge number of images that allowed scientists to assess the sky. The images estimate that our galaxy is surrounded by a halo of dark matter, thin gas and few stars, remnants of dwarf galaxies that were once swallowed up by the Milky Way. Having a sufficient amount of data, scientists were able to assemble a “skeleton” of dead galaxies. It’s like in paleontology - it’s difficult to say from a few bones what a creature looked like, but with enough data, you can assemble a skeleton and guess what the lizard was like. So it is here: the information content of the images made it possible to recreate eleven galaxies that were swallowed up by the Milky Way.

Scientists are confident that as they observe and evaluate the information they receive, they will be able to find several more new disintegrated galaxies that were “eaten” by the Milky Way.

We're under fire

According to scientists, the hypervelocity stars located in our galaxy did not originate in it, but in the Large Magellanic Cloud. Theorists cannot explain many aspects regarding the existence of such stars. For example, it is impossible to say exactly why a large number of hypervelocity stars are concentrated in Sextant and Leo. Having revised the theory, scientists came to the conclusion that such a speed can only develop due to the influence of a black hole located in the center of the Milky Way.

Recently, more and more stars have been discovered that do not move from the center of our galaxy. After analyzing the trajectory of ultra-fast stars, scientists were able to find out that we are under attack from the Large Magellanic Cloud.

Death of the planet

By observing the planets in our galaxy, scientists were able to see how the planet died. She was consumed by the aging star. During the expansion and transformation into a red giant, the star absorbed its planet. And another planet in the same system changed its orbit. Having seen this and assessed the state of our Sun, scientists came to the conclusion that the same thing would happen to our luminary. In about five million years it will become a red giant.

How the galaxy works

Our Milky Way has several arms that rotate in a spiral. The center of the entire disk is a gigantic black hole.

We can see the galactic arms in the night sky. They look like white stripes, reminiscent of a milk road that is strewn with stars. These are the branches of the Milky Way. They are best seen in clear weather in the warm season, when there is the most cosmic dust and gases.

The following arms are distinguished in our galaxy:

1. Angle branch.
2. Orion. Our solar system is located in this arm. This sleeve is our “room” in the “house”.
3. Carina-Sagittarius sleeve.
4. Perseus branch.
5. Branch of the Shield of the Southern Cross.

It also contains a core, a gas ring, and dark matter. It supplies about 90% of the entire galaxy, and the remaining ten are visible objects.

Our Solar System, the Earth and other planets are a single whole of a huge gravitational system that can be seen every night in a clear sky. In our “home” a variety of processes are constantly taking place: stars are born, they decay, we are bombarded by other galaxies, dust and gases appear, stars change and go out, others flare up, they dance around... And all this happens somewhere out there, far away in a universe about which we know so little. Who knows, maybe the time will come when people will be able to reach other branches and planets of our galaxy in a matter of minutes, and travel to other universes.

The science

Each person has his own idea of ​​what home is. For some it's a roof over their head, for others a home is... planet Earth, a rocky ball that plows through outer space along its closed path around the Sun.

No matter how big our planet may seem to us, it is just a grain of sand in giant star system, the size of which is difficult to imagine. This star system is the Milky Way galaxy, which can also rightfully be called our home.

Galaxy Sleeves

Milky Way- a spiral galaxy with a bar that runs through the center of the spiral. About two-thirds of all known galaxies are spiral, and two-thirds of them are barred. That is, the Milky Way is included in the list most common galaxies.

Spiral galaxies have arms that extend out from the center, like wheel spokes that twist in a spiral. Our solar system is located in the central part of one of the arms, which is called Orion's sleeve.

The Orion Arm was once thought to be a small "offshoot" of larger arms such as Perseus arm or Shield-Centauri arm. Not long ago, it was suggested that the Orion arm is indeed branch of the Perseus arm and does not leave the center of the galaxy.

The problem is that we cannot see our galaxy from the outside. We can only observe those things that are around us, and judge what shape the galaxy has, being, as it were, inside it. However, scientists were able to calculate that this sleeve has a length of approximately 11 thousand light years and thickness 3500 light years.

Supermassive black hole

The animation below shows the actual motion of stars around a black hole. from 1997 to 2011 in the region of one cubic parsec in the center of our galaxy. When stars approach a black hole, they loop around it at incredible speeds. For example, one of these stars, S 0-2 moves at speed 18 million kilometers per hour: black hole first attracts her, and then sharply pushes her away.

Just recently, scientists observed how a cloud of gas approached a black hole and was torn to pieces by its massive gravitational field. Parts of this cloud were swallowed up by the hole, and the remaining parts began to resemble long thin noodles longer than 160 billion kilometers.

Magneticparticles

In addition to the presence of a supermassive all-consuming black hole, the center of our galaxy boasts incredible activity: old stars die, and new ones are born with enviable consistency.

Not long ago, scientists noticed something else at the galactic center - a stream of high-energy particles that extend a distance 15 thousand parsecs across the galaxy. This distance is approximately half the diameter of the Milky Way.

The particles are invisible to the naked eye, but magnetic imaging shows that particle geysers occupy approx. two thirds of the visible sky:

What is behind this phenomenon? For one million years, stars appeared and disappeared, feeding never stopping flow, directed towards the outer arms of the galaxy. The total energy of the geyser is a million times greater than the energy of a supernova.

Particles move at incredible speeds. Based on the structure of the particle flow, astronomers built magnetic field model, which dominates our galaxy.

Newstars

How often do new stars form in our galaxy? Researchers have been asking this question for many years. It was possible to map the areas of our galaxy where there is aluminum-26, an isotope of aluminum that appears where stars are born or die. Thus, it was possible to find out that every year in the Milky Way galaxy 7 new stars and approximately twice in a hundred years a large star explodes in a supernova.

The Milky Way Galaxy does not produce the largest number of stars. When a star dies, it releases such raw materials into space as like hydrogen and helium. Over hundreds of thousands of years, these particles coalesce into molecular clouds that eventually become so dense that their center collapses under their own gravity, thus forming a new star.

It looks like a kind of eco-system: death feeds new life. Particles from a particular star will be part of a billion new stars in the future. This is how things are in our galaxy, which is why it is evolving. This leads to the formation of new conditions under which the likelihood of the emergence of Earth-like planets increases.

Planets of the Milky Way galaxy

Despite the constant death and birth of new stars in our galaxy, their number has been calculated: the Milky Way is home to approximately 100 billion stars. Based on new research, scientists suggest that every star is orbited by at least one planet or more. That is, in our corner of the Universe there is only from 100 to 200 billion planets.

The scientists who came to this conclusion studied stars like red dwarfs of spectral class M. These stars are smaller than our Sun. They make up 75 percent of all the stars in the Milky Way. In particular, researchers paid attention to the star Kepler-32, which sheltered five planets.

Planets, unlike stars, are difficult to detect because they do not emit their own light. We can say with certainty that there is a planet around a star only when it stands in front of his star and blocks out its light.

The planets of Kepler -32 behave exactly like exoplanets orbiting other M dwarf stars. They are located approximately at the same distance and have similar sizes. That is, the Kepler -32 system is typical system for our galaxy.

If there are more than 100 billion planets in our galaxy, how many of them are Earth-like planets? It turns out, not so much. There are dozens of different types of planets: gas giants, pulsar planets, brown dwarfs, and planets where molten metal rains from the sky. Those planets that consist of rocks can be located too far or too close to the star, so they are unlikely to resemble Earth.

The results of recent studies have shown that in our galaxy there are more terrestrial planets than previously thought, namely: from 11 to 40 billion. Scientists took as an example 42 thousand stars, similar to our Sun, and began to look for exoplanets that can orbit around them in a zone where it is not too hot and not too cold. Was found 603 exoplanets, among which 10 matched the search criteria.

By analyzing data about stars, scientists have proven the existence of billions of Earth-like planets that they have yet to officially discover. Theoretically, these planets are capable of maintaining temperatures for existence of liquid water on them, which, in turn, will allow life to arise.

Collision of galaxies

Even if new stars are constantly being formed in the Milky Way galaxy, it will not be able to increase in size, unless it gets new material from somewhere else. And the Milky Way is really expanding.

Previously, we were not sure exactly how the galaxy manages to grow, but recent discoveries have suggested that the Milky Way is galaxy-cannibal, meaning it has consumed other galaxies in the past and will likely do so again, at least until some larger galaxy swallows it.

Using a space telescope "Hubble" and information obtained from photographs taken over seven years, scientists have discovered stars at the outer edge of the Milky Way that move in a special way. Instead of moving toward or away from the center of the galaxy like other stars, they appear to drift toward the edge. It is believed that this star cluster is all that remains of another galaxy that was absorbed by the Milky Way galaxy.

This collision apparently occurred several billion years ago and, most likely, it will not be the last. Considering the speed at which we are moving, our galaxy through 4.5 billion years will collide with the Andromeda galaxy.

Influence of satellite galaxies

Although the Milky Way is a spiral galaxy, it is not exactly a perfect spiral. At its center there is a kind of bulge, which appeared as a result of hydrogen gas molecules escaping from the flat disk of the spiral.

For years, astronomers have puzzled over why the galaxy has such a bulge. It is logical to assume that the gas is drawn into the disk itself, and does not escape out. The longer they studied this question, the more confused they became: the molecules of the bulge are not only pushed outward, but also vibrate at their own frequency.

What could cause this effect? Today, scientists believe that dark matter and satellite galaxies are to blame - Magellanic Clouds. These two galaxies are very small: taken together they make up only 2 percent of the total mass of the Milky Way. This is not enough to have an impact on him.

However, when dark matter moves through the clouds, it creates waves that apparently influence the gravitational attraction, strengthening it, and hydrogen under the influence of this attraction escapes from the center of the galaxy.

Magellanic Clouds orbit the Milky Way. The spiral arms of the Milky Way, under the influence of these galaxies, seem to sway in the place where they pass.

Twin galaxies

Although the Milky Way galaxy can be called unique in many respects, it is not very rare. Spiral galaxies predominate in the Universe. Considering that only in our field of vision are about 170 billion galaxies, we can assume that somewhere there are galaxies very similar to ours.

What if there is a galaxy somewhere - an exact copy of the Milky Way? In 2012, astronomers discovered such a galaxy. It even has two small moons that orbit it that exactly match our Magellanic Clouds. By the way, only 3 percent spiral galaxies have similar companions, whose lifespan is relatively short. The Magellanic Clouds are likely to dissolve in a couple of billion years.

To discover such a similar galaxy, with satellites, a supermassive black hole in the center and the same size, is incredible luck. This galaxy was named NGC 1073 and it's so similar to the Milky Way that astronomers are studying it to find out more about our own galaxy. For example, we can see it from the side and thus better imagine what the Milky Way looks like.

Galactic year

On Earth, a year is the time during which the Earth manages to make full revolution around the Sun. Every 365 days we return to the same point. Our solar system revolves in the same way around a black hole located at the center of the galaxy. However, it makes a full revolution in 250 million years. That is, since the dinosaurs disappeared, we have only made a quarter of a full revolution.

Descriptions of the solar system rarely mention that it moves through space, like everything else in our world. Relative to the center of the Milky Way, the solar system moves at a speed 792 thousand kilometers per hour. To put it into perspective, if you were moving at the same speed, you could travel around the world in 3 minutes.

The period of time during which the Sun manages to make a complete revolution around the center of the Milky Way is called galactic year. It is estimated that the Sun has lived only 18 galactic years.