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The Sun, in relation to the nearest stars, moves at a speed of 16.5 km/s. Its flight (and with it the entire solar system) is directed to a point lying on the border of the constellations Hercules and Lyra, at approximately an angle of 25° to the plane of the Galaxy. To travel 50 light years of space at such a speed requires a million years. The orbit of our star around the center of the Galaxy is oscillatory: every 33 million years it crosses the galactic equator, then rises above its plane to a height of 230 light years and again falls down to the equator. It takes 250 million years for the Sun to complete a full revolution. But one should distinguish between the movement of the Sun relative to the center of the Galaxy and the movement of relatively nearby stars. After all, when talking about the speed of, for example, an airplane, we do not take into account the speed of the Earth’s revolution around the Sun. Likewise, astronomers do not take into account the galactic orbital speed when considering the speed of movement of our star in relation to the nearest stars.

solar system surrounds a local interstellar cloud, warm and dense, which, like all clouds, consists of gas and dust. Moreover, the mass of dust is only 1% of the mass of the entire interstellar cloud. And the gas in it consists of 90% hydrogen and 9.99% helium. Heavier elements total about 0.01% of the mass. The Sun is located within this cloud in an area sometimes called the local "bubble", which is a large and relatively empty space. By the way, space is so empty that it’s hard to even imagine! The best, most “empty” modern laboratory vacuum is 10,000 times denser than ordinary interstellar clouds (quite visible in photographs taken with telescopes), which are thousands of times denser than the local “bubble”! The density of this “bubble” is only 1 atom per cubic decimeter! But its temperature is truly astronomical: about 1 million ° K! In comparison, the local interstellar cloud surrounding the “bubble” is “slightly warm”, its temperature is 7000° K.

The local “bubble” is surrounded by a large ring of young stars and zones in which star formation continues, called the Gould Belt. It can be seen at night as a streak bright stars, stretching from Orion to Scorpio and inclined at an angle of 20° to the galactic plane. The North Pole of the Gould Belt is projected onto celestial sphere close to the so-called Lockman hole, a zone containing the smallest amount of interstellar gas between the Sun and extragalactic space.

Active star formation at the boundaries of the local “bubble” regulates the distribution of interstellar matter. The closest region for the formation of new suns is located at a distance of approximately 400 light years from the Sun (on the outskirts of the local “bubble”) in the Scorpius-Centauri association. The molecular clouds in this region are much colder (less than 100°K) and many times denser (more than 1000 atoms per cubic centimeter) than the local interstellar cloud. The trajectory of the Sun in the Galaxy, determined by scientists, shows that it has been moving through the Gould Belt, being in a region of very low density of interstellar matter for several million years. The probability of a collision with a large and dense interstellar cloud in this region is very small. And since at the moment we are slowly moving towards the exit from the local “bubble”, most likely there will be no collisions with other gas and dust clouds over the next million years.

But it’s worth thinking about how a collision with an interstellar cloud might affect the Earth’s climate in the distant, but still real, future. By the way, I wonder if it is just a coincidence that humans appeared on Earth while the Sun was traveling through a relatively empty region of space?

Despite the fact that there are no massive interstellar clouds within a radius of 100 light years, the local galactic environment seems to be able to change over a much longer period without us noticing. short term. It should be noted: the low density of the local “bubble” allows shock waves and ejected supernova shells rushing past the Sun to easily expand into free space. Indeed, scientists have information that for the last 250,000 years, the solar system has been affected by a continuous flow of interstellar particles from the Scorpius-Centauri association. However, there are suspicions that the immediate galactic environment of the Sun could have changed even over the last 2000 years! For now, such statements are made with caution, since astronomers have not yet fully understood complex structure local interstellar cloud.

The cloud around the Solar System is part of the material ejected from the Scorpius-Centauri association, and moving perpendicular to the direction of the Sun (relative to nearby stars). This is confirmed by observations that show how a stream of interstellar particles flies into the Solar System at a speed of 26 km/s from a region lying along the ecliptic at a distance of 15° from the direction to the center of the Galaxy.

The question of the origin of the local “bubble” and the local interstellar cloud still remains open. Some astronomers believe that they formed in the space between the spiral arms of our Galaxy after it was cleared of dense interstellar matter by powerful shock waves that arose during the process of star formation in the constellations Scorpius, Centaurus and Orion. Other scientists are confident that the formation of this relatively free space was caused by a Supernova explosion in the vicinity of the Sun. The origin of the term "bubble" itself is associated with the idea that the Solar System is located inside a Supernova remnant.

The local interstellar wind blowing through our planetary system interacts with the solar wind, which is a hot plasma consisting of charged particles (mainly protons, helium nuclei and electrons) and carried away from the Sun at high speed. The source of this wind is solar corona, heated to millions of degrees. It is just very clearly visible during full solar eclipse in the form of a delightful crown surrounding the disk. The solar wind also contains a magnetic field, spirally twisted due to the rotation of the Sun. It is blown out of the corona at supersonic speed and reaches the orbit of Pluto before meeting the interstellar wind on its way. As the solar wind approaches the boundaries of the solar system, its density and speed decrease. At a distance of 80-100 astronomical units, a shock zone is formed, the formation of which is associated with the transition of the solar wind speed from supersonic to subsonic. The final stop of the solar wind occurs in the braking zone, located 130-150 astronomical units from the Sun. The modern model of the heliosphere suggests that it is shaped very similar to a drop of water. This beautiful shape is mainly due to the interstellar wind flowing around the solar wind plasma.

Mostly neutral interstellar atoms of hydrogen and helium penetrate into the heliosphere. Moreover, 98% of the gas inside the heliosphere (excluding gas associated with comets and planetary bodies) is interstellar gas. This happens because the densities of the solar and interstellar winds in the region of Jupiter's orbit become equal.

For the first time, interstellar gas in the Solar system was discovered with the help of a satellite that examined neutral hydrogen in the upper layers of the Earth's atmosphere. In interstellar outer space Hydrogen has a low temperature, so its electron occupies a position corresponding to the minimum energy level. But when a neutral interstellar hydrogen atom approaches the Sun, it receives energy from intense solar radiation, and its electron moves into an orbit corresponding to a higher energy level. When returning to a low-energy state, the electron emits a photon in the ultraviolet range, which is detected using satellite equipment.

Since this discovery, many other phenomena have been discovered indicating the presence of interstellar gas in the Solar system. A few astronomical units from the Sun, most interstellar hydrogen atoms are ionized. Helium atoms manage to approach the Sun to a distance of one astronomical unit before they are ionized by solar radiation, and individual atoms completely avoid ionization. The moving stream of interstellar atoms is focused by solar gravity into a cone through which the Earth passes every year at the end of November.

Ionized helium atoms are picked up by the flow of solar wind and carried away to the boundary of the helium sphere. Since such “picked up” ions are products of the interaction of the solar wind with interstellar matter, measuring their quantity and characteristics is the key to unraveling the properties of the interstellar matter itself. The discovery of "trapped" ions occurred in the mid-1980s.

After helium ions reach the shock zone at the boundary of the heliosphere, they are accelerated and form a component known as the “anomalous component of cosmic rays.” They are “anomalous” because their energy is not enough to penetrate the Solar System from the outside; they had to form inside it. In other words, we observe how these particles literally rush around inside the heliosphere: they fly into the Solar system as neutral atoms, move to the boundary of the heliosphere as “caught ions” and again return inside the Solar system in the form of “anomalous cosmic rays".

But atom-sized particles are not the only “aliens” flying into the solar system from space. Dust detectors installed on board the famous Ulysses and Galileo spacecraft recorded a stream of large dust particles moving at the same speed and in the same direction as the local interstellar wind. Their size is 0.2-6 microns (smaller dust particles are electrically charged, so they cannot penetrate into the inner regions of the Solar System). The largest particles have trajectories that are completely independent of the solar wind or solar activity cycles. Much like helium atoms, these particles are focused by solar gravity, and the Earth passes through their compacted stream every year at the end of November.

Our galactic environment is changing, and we don't know what other objects we might encounter in the future. Observations of neighboring interstellar clouds show that they contain small condensations (size from 100 to 10,000 AU) that can contain up to 1000 particles per cubic centimeter! When the Sun passed through such a dense nebula, the size of the heliosphere would change simply catastrophically. Computer simulation Such a meeting shows that if the density of the local interstellar wind increased to 10 particles per cubic centimeter, the heliosphere would shrink to 15 AU. That is, and the heliopause would lose stability. Density of interstellar hydrogen at a distance of 1 a. e. would grow to 2 atoms per cubic centimeter, which would significantly change the composition of the environment surrounding the Earth. With a local interstellar wind density of 1000 particles per cubic centimeter, planets such as Saturn, Uranus, Neptune and Pluto would be completely immersed in interstellar gas. But within the Earth's orbit, the solar wind would still prevail over the interstellar wind. Therefore, we can say that the solar wind protects the inner planets from changes in the galactic environment of the Sun.

There is evidence that similar changes may have occurred more than once in the past. Studies of beryllium-10 concentrations (half-life 1.5 million years) in Antarctica have detected two spikes, occurring 60,000 and 33,000 years ago. Such bursts are explained by a strong change in the level of cosmic rays, which could be a consequence of either a distant supernova explosion or an encounter with a dense part of the local interstellar cloud. A possible supernova outbreak is supported by the discovery of elevated concentrations of iron-60 in seabed sediments. Iron-60 — radioactive isotope iron formed during supernova explosions. This discovery may indicate a Supernova explosion about 5 million years ago at a distance of up to 90 light years from the Sun.

Amazing opportunities are opening up for researchers in this area! After all, understanding the interaction of interstellar and solar winds in the past and present would make it possible to predict the behavior of the heliosphere in the future. The compilation of the most detailed galactic map could be of great help here.

The best solution to the issue would be to launch an interstellar probe for direct measurements of environmental parameters. This would make it possible to study in detail the properties of local gas-dust clouds: density, ionization, molecular composition, intensity of magnetic fields, dynamic characteristics of their interaction with the solar wind. If the program to launch such a probe received funding, then results could be expected in the near future. After all, the use of modern engines and perturbation maneuvers in the gravitational fields of the planets of the Solar system makes it possible to accelerate spacecraft up to speeds of 4000 km/s. It would have reached the boundaries of the solar system 15 years after launch. This event will be the beginning of a new era of final entry into interstellar space!

Let's wait a little longer.

Alexander Pugach

Outside the galaxies lies intergalactic space.

The boundary between interplanetary and interstellar space is the heliopause, in which the solar wind is slowed down by interstellar matter. The exact distance of this border region from the Sun is not yet known; it is supposedly located at four times Pluto's distance from the Sun (approximately 24 billion kilometers).

Information on the size of the heliosphere and the physical conditions in the heliopause is expected from the US probes Pioneer 10, Pioneer 11, Voyager 1 and Voyager 2, the first man-made objects that will enter the region in about a year and begin sending back data.

The boundary between interstellar and intergalactic space is a galactic gas flow rushing outward, which collides with intergalactic matter and forms outer layer galaxies.

Travel in interstellar space is a popular theme in science fiction novels. Technically, such projects are not yet feasible due to the very large distances.

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See what “Interstellar space” is in other dictionaries:

interstellar space- tarpžvaigždinė erdvė statusas T sritis radioelektronika atitikmenys: engl. interstellar space vok. interstellarer Raum, m rus. interstellar space, n pranc. espace interstellaire, m... Radioelektronikos terminų žodynas

Interstellar matter- Map of the local interstellar cloud The interstellar medium (ISM) is the matter and fields that fill interstellar space inside galaxies. Composition: interstellar gas, dust (1% of the gas mass), interstellar magnetic fields, cosmic rays, as well as ... ... Wikipedia

Interstellar magnetic field- one of the components of the interstellar medium (See Interstellar medium). The intensity and structure of the magnetic field can be estimated from astronomical observations of various types. One of them is the study of the radio emission of the Galaxy,... ... Great Soviet Encyclopedia

Interstellar flight- Interstellar flight - travel between stars by manned vehicles or automatic stations. Four automatic stations Pioneer 10, Pioneer 11, Voyager 1, Voyager 2 reached the third escape velocity and left the solar... ... Wikipedia

Interstellar flights- travel between stars by manned vehicles or automatic stations. Spaceship flights occupy a significant place in science fiction. Four automatic stations Pioneer 10, Pioneer 11, Voyager 1, Voyager 2 reached the third... ... Wikipedia

Interstellar flights- Interstellar flights travel between stars by manned vehicles or automatic stations. Spaceship flights occupy a significant place in science fiction. Four automatic stations Pioneer 10, Pioneer 11, Voyager 1, Voyager 2... ... Wikipedia

Interstellar comet- Interstellar comets are comets that hypothetically exist in the interstellar medium, not connected by gravitational forces with any star. Although no such comet has yet been discovered, it is assumed that these objects are very... ... Wikipedia

Interstellar medium- Map of the local interstellar cloud Interstellar medium (ISM) matter and fields filling interstellar space inside galaxies ... Wikipedia

INTERSTELLAR MEDIUM- matter that fills the space between stars inside galaxies. Matter in the space between galaxies is called. intergalactic environment (see Clusters of galaxies. Intergalactic gas). Gas in shells around stars (circumstellar shells) often... ... Physical encyclopedia

Interstellar dust- Interstellar dust is solid microscopic particles, along with interstellar gas, filling the space between stars. It is currently believed that dust grains have a refractory core surrounded by organic matter or an ice shell.... ... Wikipedia

The space between the stars is not empty. Giant clusters and rotating masses of gas and dust form beautiful, brightly glowing clouds of matter. Such clouds are called nebulae, and many of them are the very places where new stars are born. In the Orion Nebula, new stars are forming right now.

To see the clouds aching Milky Way with the naked eye, you will have to wait until there is no Moon in the sky, and choose a place for observation that is far from the bright lights of cities and towns. Then you will be able to discern a faintly luminous stripe running across the entire sky, about the width of your palm at arm's length.

The best place to see the Milky Way is in southern hemisphere, but on summer nights it is not difficult to see it in the north. The light haze is intersected by “cracks” and “holes” that are clearly visible in the photographs.

For a long time, astronomers believed that these dark spots in the Milky Way were like tunnels among the stars. We now know that this is absolutely false. In reality, areas with no a large number stars are clouds of gas and dust. Finely crushed dust and gas are scattered there, in the depths of space, and block the stars of the Milky Way from us.

Action of dust in space

On Earth, the setting Sun appears red because dust in the air scatters blue light more than red light. So most of the red rays pass through such hazy air, but not the blue ones. The situation is similar in space. Fog in outer space not only makes stars appear dimmer, it also makes them appear redder. Near the center of our Galaxy, in the constellation Sagittarius, there is so much dust that light does not pass through it at all, so the center of the Galaxy is absolutely invisible to us. To penetrate these dense clouds of dust and still find out what is happening in the very heart of the Milky Way, astronomers have to resort to the help of radio telescopes and infrared telescopes.

Under the influence of stellar singing, grains of dust in outer space warm up slightly, especially in the vicinity of very hot stars. Special infrared telescopes can see how dust particles emit heat, giving us the opportunity to look inside dust clouds. When under the influence gravitational forces part of the gas or dust-

When the cloud begins to compress, the cloud is forced to give up some of its energy. Thus, the collapse (compression) of the cloud releases energy. This energy is visible as infrared radiation.

Stardust

The dust found in the Milky Way is stardust. The outer layers of giant stars are carried away into outer space. Old stars explode and scatter atoms of oxygen, carbon and iron into space. Silicon and iron are capable of forming tiny crystals, which then move through space, acquiring a coating of oxygen, carbon and nitrogen. These little grains are miniature chemical factories. On the surface of dust particles, atoms, for example, carbon and oxygen, attach to each other, forming molecules - say, carbon monoxide.

Hello! Hydrogen calls Earth!

The most common substance in interstellar space, and indeed in the Universe in general, is hydrogen. Radio astronomers hear the noise produced by this gas in all parts of our Galaxy. A hydrogen atom has only one electron. Sometimes an electron is thrown out of its orbit, and then a radio signal is sent into space. Each individual signal is very weak, but there is so much hydrogen in outer space that astronomers are able to obtain the overall, cumulative effect of all hydrogen in the form of radiation with a length of a full 21 cm. Hydrogen maps of the Milky Way reveal a beautiful spiral shape of our Galaxy with a lot of hydrogen , located in its spiral arms.

Hydrogen clouds rotate in the Galaxy in the same way as planets revolve around the Sun. The speed at which a hydrogen cloud moves depends on how far it is from the center of our Galaxy. From the velocities of the hydrogen clouds we can calculate the total volume and shape of the Galaxy.

Nebulae emitting light

Interstellar clouds are mainly composed of hydrogen. In the depths of space they are too cold to glow. But sometimes a hydrogen cloud surrounds a hot star. And then the nebula appears before us in the form of a cloud of hot gas. The star heats the hydrogen until it glows pinkish. In the Large Magellanic Cloud there is a huge self-luminous nebula emitting pink light.

Nebulas that absorb light

The interstellar cloud may be too cold to emit light. And even vice versa, a cold-nose cloud can absorb the light of bright objects (for example, stars) located behind it. In this case, we see him as a dark silhouette against a light background. The Coalsack, a dark spot in the southern Milky Way, is a light-absorbing nebula visible to the naked eye.

Nebulae reflecting light

Sometimes a cold cloud in outer space can be visible because the dust it consists of reflects the light of nearby stars. The dust forms a delicate reflection nebula around the brightest stars in a cluster called the Pleiades. Nebulae that reflect light appear blue in photographs.

Interstellar medium

The matter located in the space between stars is called the interstellar medium. Most of it is concentrated in the spiral arms of the Milky Way. The temperature of interstellar matter ranges from several degrees higher absolute zero in the coldest dust clouds up to a million degrees in the hottest gas clouds.

If you were to go into space to the spiral arm of the Galaxy, you would find only about one atom of gas per cubic centimeter. There would be several hundred dust grains in a cubic kilometer of space. Thus, reversible, the interstellar medium is very rarefied. However, even in dense clouds the concentration of the substance can be 1000 times higher than the average. But even in a dense cloud cubic centimeter there are only a few hundred atoms. The reason why we are still able to observe interstellar matter, despite its very rarefied nature, is that we see it in a large thickness of space. In a typical spiral galaxy, interstellar matter makes up 5 to 10 percent of all visible matter.

Our Solar System is located in a region of the Galaxy where the density of interstellar matter is unusually low. This area is called the Local Bubble; it extends in all directions for about 300 light years. It is possible that most of all the matter that could be located near the Sun was carried away under the influence of some processes. One of the proposed ideas is that once upon a time in the vicinity of the solar system there was a colossal explosion of several big stars. And the interstellar gas was thrown back by the explosive completeness into distant regions of outer space.

Giant molecular clouds

The most massive objects The Milky Way is made up of giant molecular clouds. Their mass can exceed the mass of the Sun by a million times. The Orion Nebula is just part of a giant molecular cloud that is about 500 times more massive than our Sun. In the mysterious depths of black clouds, astronomers have discovered an absolutely astonishing array of molecules. That space material includes water, ammonia and alcohol. There is also formic acid - the same one found in biting ants - as well as hydrocyanic acid. The acids from these molecules are classified as organic because they contain carbon.

The chemistry of these amazing clouds is actually very simple. Different atoms can be imagined as parts of some kind of construction kit. Carbon, hydrogen, oxygen, nitrogen and other atoms can be combined together in a variety of ways - this is how all kinds of molecules are obtained, which do not collapse in the cloud due to its very low temperature. Simple elements can combine to form molecules of amino acids and proteins. On Earth, these same substances, found in nature, combine and form giant molecules of plant and animal organisms.

Voyager 2 passed an incredible milestone in its exploration of the solar system by entering interstellar space, but neither its journey nor scientific research it doesn't end there.
During a press conference at the annual meeting of the American Geophysical Union on December 10, scientists and engineers said that while they are excited about crossing the border, Voyager 2 and its sister Voyager 1 are still quite capable. The data they collected will help shed light on how particles coming from the Sun collide with particles in the interstellar wind beyond.
Voyagers are the first spacecraft to date that humans have sent to the edge of the solar system, called the heliopause. If all goes well, both ships will continue to travel for years to come.

A key challenge for Voyager 2 is coping with the gradual loss of heat and energy. The ship currently operates at around 3.6°C, and power output drops by 4 watts every year. This means the team will eventually have to shut down the tools.
It is estimated that the devices will operate for at least another 5–10 years, but the amount of scientific data will gradually decrease. Although Voyager 1 was the first to cross the heliopause, Voyager 2 offers several new possibilities. It has a working plasma detector, whereas its predecessor's instrument stopped working decades ago. And due to the current stage of the solar cycle, Voyager 2 could end up in the heliopause again as the solar bubble expands.
Even once the heliosphere is behind Voyager 2, it will be able to tell scientists about the flow of interstellar wind affecting the heliopause and the local bubble surrounding the heliosphere. With its help, scientists will be able to detect galactic cosmic rays, high-energy atoms and a whole range of elements that move throughout the Universe almost at the speed of light.
“Galactic cosmic radiation acts as a messenger to our local galactic neighborhood. And now we can look at the galaxy through the foggy lens of our heliosphere,” said NASA astrophysicist George Denolfo.
Voyager 2 may not only tell us about our own surroundings, but also shape our understanding of exoplanets. Each solar system is located in its own equivalent of the heliosphere, touching its local interstellar space. This marginal balance determines how habitable these planets are.
Although Voyager's instruments will not last forever, both spaceship will continue on their way. Within about 300 years, they will reach the inner edge of the Oort Cloud, the sphere of comets surrounding the solar system. Crossing this field will take about 30,000 years. Once the probes completely leave our system, they will enter a long orbit around the heart of the Milky Way, where they will circle for millions, if not billions of years, becoming humanity's first emissaries at such a distance.