Stages of formation of the solar system and earth. How the solar system began. Problems in studying the formation of the Solar System

Plan:

1 Formation
2 Subsequent evolution
- 2.1 Terrestrial planets
- 2.2 Asteroid belt
- 2.3 Planetary migration
- 2.4 Heavy Bombing
- 2.5 Formation of satellites
3 Future
- 3.1 Long term sustainability
- 3.2 Moons and rings of planets
- 3.3 Sun and planets
4 Galactic interaction
- 4.1 Collision of galaxies

Introduction

According to modern ideas, formation of the solar system began about 4.6 billion years ago with the gravitational collapse of a small part of a giant interstellar molecular cloud. Most of the matter ended up in the gravitational center of collapse with the subsequent formation of a star - the Sun. The matter that did not fall into the center formed a protoplanetary disk rotating around it, from which the planets, their satellites, asteroids and other small bodies of the Solar System were subsequently formed.

Protosun and protoplanets as imagined by an artist

1. Formation

The hypothesis of the formation of the solar system from a cloud of gas and dust - the nebular hypothesis - was originally proposed in the 18th century by Emmanuel Swedenborg, Immanuel Kant and Pierre-Simon Laplace. Its further development took place with the participation of many scientific disciplines, including astronomy, physics, geology and planetary science. With the advent of the space age in the 1950s, and with the discovery of planets outside the solar system (exoplanets) in the 1990s, this model has undergone many tests and improvements to explain new data and observations.

According to the currently generally accepted hypothesis, the formation of the Solar System began about 4.6 billion years ago with the gravitational collapse of a small part of a giant interstellar gas and dust cloud. In general terms, this process can be described as follows:

The trigger for the gravitational collapse was a small (spontaneous) compaction of the substance of the gas and dust cloud (possible reasons for which could be both the natural dynamics of the cloud and the passage of a shock wave from a supernova explosion through the substance of the cloud, etc.), which became the center of gravitational attraction for the surrounding substance - the center of gravitational collapse. The cloud already contained not only primordial hydrogen and helium, but also numerous heavy elements (metals) left over from stars of previous generations. In addition, the collapsing cloud had some initial angular momentum.
During the process of gravitational compression, the size of the gas and dust cloud decreased and, due to the law of conservation of angular momentum, the speed of rotation of the cloud increased. Due to the rotation, the compression rates of the clouds parallel and perpendicular to the rotation axis differed, which led to the flattening of the cloud and the formation of a characteristic disk.
As a consequence of compression, the density and intensity of collisions of particles of matter with each other increased, as a result of which the temperature of the substance continuously increased as it was compressed. The central regions of the disk heated up most strongly.
When the temperature reached several thousand Kelvin, the central region of the disk began to glow - a protostar formed. Matter from the cloud continued to fall onto the protostar, increasing the pressure and temperature at the center. The outer regions of the disk remained relatively cold. Due to hydrodynamic instabilities, individual compactions began to develop in them, which became local gravitational centers for the formation of planets from the matter of the protoplanetary disk.
When the temperature in the center of the protostar reached millions of kelvins, a thermonuclear reaction of hydrogen combustion began in the central region. The protostar turned into an ordinary main sequence star. In the outer region of the disk, large condensations formed planets rotating around the central star in approximately the same plane and in the same direction.

2. Subsequent evolution

Previously, it was believed that all planets formed approximately in the orbits where they are now, but at the end of the 20th and beginning of the 21st centuries this point of view changed radically. It is now believed that at the dawn of its existence the solar system looked completely different from what it looks like now. According to modern ideas, the outer Solar System was much more compact in size than it is now, the Kuiper Belt was much closer to the Sun, and in the inner Solar System, in addition to the celestial bodies that have survived to this day, there were other objects no smaller in size than Mercury.

2.1. Terrestrial planets

A gigantic collision of two celestial bodies that gave birth to the Earth's satellite, the Moon.

At the end of the era of planet formation, the inner Solar System was populated by 50-100 protoplanets with sizes ranging from lunar to Martian. Further growth in the size of celestial bodies was due to collisions and mergers of these protoplanets with each other. For example, as a result of one of the collisions, Mercury lost most of its mantle, while as a result of another, the Earth's satellite, the Moon, was born. This phase of collisions continued for about 100 million years until there were only 4 massive celestial bodies known today left in orbit.

One of the unresolved problems with this model is the fact that it cannot explain how the initial orbits of protoplanetary objects, which had to be highly eccentric to collide with each other, could end up giving rise to stable and nearly circular orbits of the remaining four planets. According to one hypothesis, these planets were formed at a time when interplanetary space still contained a significant amount of gas and dust material, which, due to friction, reduced the energy of the planets and made their orbits smoother. However, this same gas should have prevented the occurrence of large elongations in the initial orbits of the protoplanets. Another hypothesis suggests. that the correction of the orbits of the inner planets occurred not due to interaction with gas, but due to interaction with the remaining smaller bodies of the system. As large bodies passed through a cloud of small objects, the latter, due to gravitational influence, were drawn into regions of higher density, and thus created “gravitational ridges” along the path of large planets. The increasing gravitational influence of these "ridges", according to this hypothesis, caused the planets to slow down and enter a more rounded orbit.

2.2. Asteroid belt

The outer boundary of the inner Solar System lies between 2 and 4 AU. from the Sun and represents the asteroid belt. Initially, the asteroid belt contained enough matter to form 2-3 planet Earths. This area contained a large number of planetesimals that stuck together, forming increasingly larger objects. As a result of these mergers, about 20-30 protoplanets with sizes ranging from lunar to Martian were formed in the asteroid belt. However, from the time when the planet Jupiter formed in relative proximity to the belt, the evolution of this region took a different path. Powerful orbital resonances with Jupiter and Saturn, as well as gravitational interactions with more massive protoplanets in this region, destroyed the already formed planetesimals. Getting into the area of resonance when a giant planet passed nearby, the planetesimals received additional acceleration, crashed into neighboring celestial bodies and fragmented instead of smoothly merging.

As Jupiter migrated to the center of the system, the resulting disturbances became more and more pronounced. As a result of these resonances, planetesimals changed the eccentricity and inclination of their orbits and were even thrown out of the asteroid belt. Some of the massive protoplanets were also ejected from the asteroid belt by Jupiter, while other protoplanets likely migrated into the inner Solar System, where they played a final role in increasing the mass of the few remaining terrestrial planets. During this period of depletion, the influence of giant planets and massive protoplanets caused the asteroid belt to "thin" to just 1% of Earth's mass, which was made up mostly of small planetesimals. However, this value is 10-20 times greater than the modern value of the mass of the asteroid belt, which is now 1/2000 of the mass of the Earth. It is believed that the second period of depletion, which brought the mass of the asteroid belt to its current values, occurred when Jupiter and Saturn entered a 2:1 orbital resonance.

It is likely that the period of giant collisions in the history of the inner Solar System played an important role in the Earth receiving its water reserves (~6 × 10 21 kg). The fact is that water is too volatile a substance to arise naturally during the formation of the Earth. Most likely it was brought to Earth from the outer, colder regions of the Solar System. Perhaps it was the protoplanets and planetesimals ejected by Jupiter beyond the asteroid belt that brought water to Earth. Other candidates for the role of the main providers of water are also comets of the main asteroid belt, discovered in 2006, while comets from the Kuiper belt and from other distant regions supposedly brought no more than 6% of water to Earth.

2.3. Planetary migration

According to the nebular hypothesis, the two outer planets of the solar system are in the “wrong” place. Uranus and Neptune, the “ice giants” of the solar system, are located in a region where the low density of nebula matter and long orbital periods made the formation of such planets a highly unlikely event. It is believed that these two planets originally formed in orbits near Jupiter and Saturn, where there was much more building material, and only migrated to their modern positions hundreds of millions of years later.

Simulation showing the location of the outer planets and the Kuiper Belt: a) Before the 2:1 orbital resonance of Jupiter and Saturn b) The scattering of ancient Kuiper Belt objects throughout the Solar System after Neptune's orbital shift c) After Jupiter ejects Kuiper Belt objects out of the system

Planetary migration is able to explain the existence and properties of the outer regions of the Solar System. Beyond Neptune, the Solar System contains the Kuiper belt, open disk and Oort cloud, which are open clusters of small icy bodies and give rise to most of the comets observed in the Solar System. The Kuiper Belt is currently located at a distance of 30-55 AU. from the Sun, the scattered disk begins at 100 AU. from the Sun, and the Oort cloud is at 50,000 AU. from the central luminary. However, in the past the Kuiper Belt was much denser and closer to the Sun. Its outer edge was approximately 30 AU. from the Sun, while its inner edge was located directly behind the orbits of Uranus and Neptune, which in turn were also closer to the Sun (approximately 15-20 AU) and, in addition, were located in the opposite order: Uranus was further from Sun than Neptune.

After the formation of the Solar System, the orbits of all the giant planets continued to slowly change under the influence of interactions with a large number of remaining planetesimals. After 500-600 million years (4 billion years ago), Jupiter and Saturn entered a 2:1 orbital resonance; Saturn made one revolution around the Sun in exactly the time it took Jupiter to make 2 revolutions. This resonance created gravitational pressure on the outer planets, causing Neptune to escape the orbit of Uranus and crash into the ancient Kuiper belt. For the same reason, the planets began to throw the icy planetesimals surrounding them into the interior of the Solar System, while they themselves began to move away outward. This process continued in a similar way: under the influence of resonance, planetesimals were thrown into the system by each subsequent planet they met on their way, and the orbits of the planets themselves moved further and further away. This process continued until the planetesimals entered the zone of direct influence of Jupiter, after which the enormous gravity of this planet sent them into highly elliptical orbits or even threw them out of the solar system. This work in turn shifted Jupiter's orbit slightly inward [~1]. Objects ejected by Jupiter into highly elliptical orbits formed the Oort cloud, and objects ejected by migrating Neptune formed the modern Kuiper belt and scattered disk. This scenario explains why the scattered disk and Kuiper belt have low mass. Some of the ejected objects, including Pluto, eventually entered into gravitational resonance with the orbit of Neptune. Gradually, friction with the scattered disk made the orbits of Neptune and Uranus smooth again.

It is believed that, unlike the outer planets, the system's inner bodies did not undergo significant migrations because their orbits remained stable after a period of giant impacts.

2.4. Heavy Bombing

The gravitational collapse of the ancient asteroid belt likely initiated the Heavy Bombardment period, which occurred about 4 billion years ago, 500-600 million years after the formation of the Solar System. This period lasted several hundred million years and its consequences are still visible on the surface of geologically inactive bodies of the Solar System, such as the Moon or Mercury. And the oldest evidence of life on Earth dates back to 3.8 billion years ago - almost immediately after the end of the Late Heavy Bombardment period.

Giant collisions are a normal (though recently rare) part of the evolution of the solar system. Evidence of this is the collision of Comet Shoemaker-Levy with Jupiter in 1994, the fall of a celestial body on Jupiter in 2009, and the meteorite crater in Arizona. This suggests that the process of accretion in the solar system is not yet complete, and, therefore, poses a danger to life on Earth.

2.5. Formation of satellites

Natural satellites have formed on most of the planets in the Solar System, as well as on many other bodies. There are three main mechanisms of their formation:

formation from a circumplanetary disk (in the case of gas giants)
shaping from collision fragments (in case of a sufficiently large collision at a low angle)
capture of a flying object

Jupiter and Saturn have many moons, such as Io, Europa, Ganymede and Titan, which probably formed from the disks around these giant planets in the same way that these planets themselves formed from the disk around the young Sun. This is indicated by their large size and proximity to the planet. These properties are impossible for satellites acquired through capture, and the gaseous structure of the planets makes the hypothesis of the formation of moons through a collision of a planet with another body impossible.

3. Future

Astronomers estimate that the Solar System will not undergo extreme changes until the Sun runs out of hydrogen fuel. This milestone will mark the beginning of the Sun's transition from the main sequence of the Hertzsprung-Russell diagram to the red giant phase. However, even in the phase of the main sequence of a star, the Solar system continues to evolve.

3.1. Long term stability

The solar system is a chaotic system in which the orbits of the planets are unpredictable over very long periods of time. One example of such unpredictability is the Neptune-Pluto system, which is in an orbital resonance of 3:2. Despite the fact that the resonance itself will remain stable, it is impossible to predict with any approximation the position of Pluto in orbit more than 10-20 million years (Lyapunov time). Another example is the tilt of the Earth's rotation axis, which, due to friction within the Earth's mantle caused by tidal interactions with the Moon, cannot be calculated from some point between 1.5 and 4.5 billion years in the future.

The orbits of the outer planets are chaotic on large time scales: their Lyapunov times range from 2 to 230 million years. This not only means that the position of the planet in orbit from this point in the future cannot be determined to any approximation, but the orbits themselves may change extremely. The chaos of the system can manifest itself most strongly in a change in the eccentricity of the orbit, in which the orbits of the planets become more or less elliptical.

The solar system is stable in the sense that no planet is likely to collide with another or be ejected from the system within the next few billion years. However, beyond this time frame, for example, within 5 billion years, the eccentricity of Mars' orbit can increase to a value of 0.2, which will lead to the intersection of the orbits of Mars and the Earth, and therefore to a real threat of collision. During the same period of time, the eccentricity of Mercury's orbit may increase even more, and subsequently a close passage near Venus may throw Mercury out of the Solar System, or put it on a collision course with Venus itself or with the Earth.

3.2. Moons and rings of planets

The evolution of lunar systems of planets is determined by tidal interactions between the bodies of the system. Due to the difference in the gravitational force acting on the planet from the satellite in its different areas (more distant areas are attracted weaker, while closer ones are stronger), the shape of the planet changes - it seems to be slightly stretched in the direction of the satellite. If the direction of rotation of the satellite around the planet coincides with the direction of rotation of the planet, and at the same time the planet rotates faster than the satellite, then this “tidal hump” of the planet will constantly “run away” forward in relation to the satellite. In this situation, the angular momentum of the planet's rotation will be transferred to the satellite. This will cause the satellite to gain energy and gradually move away from the planet, while the planet loses energy and rotates slower and slower.

The Earth and Moon are an example of such a configuration. The Moon's rotation is tidally locked with respect to the Earth: the period of the Moon's orbit around the Earth (currently approximately 29 days) coincides with the period of the Moon's rotation on its axis, and therefore the Moon always faces the same side towards the Earth. The Moon is gradually moving away from the Earth, while the Earth's rotation is gradually slowing down. In 50 billion years, if they survive the expansion of the Sun, the Earth and Moon will become tidally locked to each other. They will enter the so-called spin-orbit resonance, in which the Moon will revolve around the Earth in 47 days, the period of rotation of both bodies around its axis will be the same, and each of the celestial bodies will always be visible only from one side for its partner.

Other examples of this configuration are the systems of Jupiter's Galilean moons, as well as most of Saturn's large moons. .

Neptune and its moon Triton, photographed during the mission's flyby Voyager 2. In the future, it is likely that this satellite will be torn apart by tidal forces, creating a new ring around the planet.

A different scenario awaits systems in which the satellite moves around the planet faster than it rotates around itself, or in which the satellite moves in the opposite direction to the direction of the planet's rotation. In such cases, the tidal deformation of the planet constantly lags behind the satellite's position. This changes the direction of transfer of angular momentum between bodies to the opposite. which in turn will lead to an acceleration of the planet’s rotation and a reduction in the satellite’s orbit. Over time, the satellite will spiral closer to the planet until at some point it either falls to the surface or atmosphere of the planet, or is torn apart by tidal forces, thus giving rise to a planetary ring. Such a fate awaits Mars' satellite Phobos (in 30-50 million years), Neptune's satellite Triton (in 3.6 billion years), Jupiter's Metis and Adrastea, and at least 16 small moons of Uranus and Neptune. Desdemona of Uranus may even collide with its neighboring moon.

And finally, in the third type of configuration, the planet and satellite are tidally fixed in relation to each other. In this case, the “tidal hump” is always located exactly under the satellite, there is no transfer of angular momentum, and, as a consequence, the orbital period does not change. An example of such a configuration is Pluto and Charon.

Before the Cassini-Huygens mission in 2004, it was believed that Saturn's rings were much younger than the Solar System, and that they would last no more than 300 million years. It was assumed that gravitational interactions with Saturn's moons would gradually move the outer edge of the rings closer to the planet, while Saturn's gravity and bombarding meteorites would finish the job, completely clearing the space around Saturn. However, data from the Cassini mission forced scientists to reconsider this point of view. Observations have recorded icy blocks of material up to 10 km in diameter, in a constant process of crushing and reshaping, constantly renewing the rings. These rings are much more massive than the rings of other gas giants. It is this large mass that is thought to have preserved the rings for the 4.5 billion years since Saturn formed, and will likely continue to do so for billions of years to come.

3.3. Sun and planets

In the long future, the biggest changes in the solar system will be associated with changes in the state of the sun due to its aging. As the Sun burns its reserves of hydrogen fuel, it will become hotter and, as a result, will consume the remaining hydrogen faster. As a result, the Sun will increase its luminosity by 10 percent every 1.1 billion years. After 1 billion years, due to an increase in solar radiation, its circumstellar habitable zone will shift beyond the current Earth's orbit: the Earth's surface will heat up so much that the presence of liquid water on it will become impossible. The evaporation of water from the surface of the oceans will create a greenhouse effect, which will lead to even more intense heating of the Earth. In this phase, the existence of life on the earth's surface will become impossible. However, it seems likely that the surface temperature of Mars will begin to gradually increase during this period. Water and carbon dioxide frozen in the bowels of the planet will begin to be released into the atmosphere, and this will lead to the creation of a greenhouse effect, further increasing the rate of heating of the surface. As a result, the atmosphere of Mars will reach conditions similar to those on Earth, and thus Mars may well become a potential refuge for life in the future.

After about 3.5 billion years from now, conditions on the Earth's surface will be similar to the modern conditions of the planet Venus.

Structure of a solar-type star and a red giant

About 5.4 billion years from now, the Sun's core will become so hot that it will start burning hydrogen in the surrounding shell. This will entail a strong expansion of the outer layers of the star, and thus the Sun will enter a new phase of its evolution, turning into a red giant. In this phase, the radius of the Sun will be 1.2 AU, which is 256 times greater than its current radius. A multiple increase in the surface area of the star will lead to a decrease in surface temperature (about 2600 K) and an increase in luminosity (2700 times more than the current value). During the red giant phase, the Sun will be strongly influenced by the stellar wind, which will blow away about 33% of its mass. It is likely that during this period, Saturn's moon Titan will reach conditions acceptable to support life.

As it expands, the Sun will completely engulf the planets Mercury and probably Venus. The fate of the Earth is less clear. Despite the fact that the radius of the Sun will include the modern Earth's orbit, the loss of mass by the star and the resulting decrease in the force of gravity will lead to the movement of planetary orbits to longer distances. And one might assume that this would allow the Earth and Venus to avoid being absorbed by the parent star, but studies from 2008 show that the Earth will most likely still be absorbed by the Sun due to tidal interactions with its outer shell.

The Ring Nebula is a planetary nebula similar to the one that the Sun will give birth to one day in the future

Gradually, the combustion of hydrogen in the regions around the solar core will lead to an increase in its mass until it reaches 45% of the mass of the star. At this point, its density and temperature will become so high that a helium flash will occur and the process of fusing helium into carbon will begin. During this phase, the Sun will decrease in size from the previous 250 to 11 radii. Its luminosity will decrease from 3000 to 54 times the level of the modern Sun, and the surface temperature will increase to 4770 K. The phase of helium synthesis into carbon will be stable, but will last only 100 million years. Gradually, as in the hydrogen burning phase, the reaction will capture helium reserves from the regions surrounding the core, which will lead to re-expansion of the star. This phase will move the Sun into the Asymptotic giant branch of the Hertzsprung-Russell Diagram. In this phase, the Sun's luminosity will increase again to 2090 modern luminosities, and the surface temperature will drop to 3500 K. This phase will last about 30 million years, after which, over the next 100,000 years, the remaining outer layers of the Sun will be thrown outward in the form of powerful jets of matter. The ejected matter will form a halo called the Planetary Nebula, which will consist of combustion products of the last phases - helium and carbon. This matter will participate in the enrichment of interstellar space with heavy elements necessary for the formation of cosmic bodies of next generations.

The process of the Sun shedding its outer layers is a relatively calm phenomenon compared, for example, with a supernova explosion. It represents a significant increase in the strength of the solar wind, not enough to destroy nearby planets. However, a significant loss of mass by the star will cause the planets to shift from their orbits, plunging the solar system into chaos. Some of the planets may collide with each other, some may leave the solar system, some may remain at a distant distance. And what will remain from the Sun in the end is a small white dwarf - a super-dense cosmic body, making up 54 percent of the original solar mass, but with a diameter approximately equal to the diameter of the Earth. Initially, this white dwarf may have a luminosity 100 times higher than the modern sun. It will consist entirely of degenerate carbon and oxygen, but will never be able to reach temperatures sufficient to begin the synthesis of these elements. Thus, the white dwarf Sun will gradually cool down, becoming dimmer and dimmer.

As the Sun dies, its gravitational influence on the bodies orbiting around it (planets, comets, asteroids) will weaken due to the loss of mass by the star. The orbits of all surviving planets will move to greater distances: if Venus, Earth and Mars still exist, their orbits will lie at approximately 1.4 AU (210,000,000 km), 1.9 AU. (280,000,000 km), and 2.8 a.u. (420,000,000 km). These and all remaining planets will turn into dark, cold blocks devoid of any forms of life. They will continue to orbit the Sun at slower speeds due to their increasing distance from the Sun and decreasing gravitational force. 2 billion years later, when the Sun cools to 6000-8000 K, the carbon and oxygen in the Sun's core will freeze, 90% of the core's mass will take on a crystalline structure. Over the next trillions of years, the Sun will completely go out and turn into a black dwarf.

4. Galactic interaction

Location of the Solar System in the Milky Way Galaxy

The Solar System moves through the Milky Way galaxy in a circular orbit approximately 30,000 light years from the galactic center at a speed of 220 km/s. The period of revolution around the center of the galaxy, the so-called galactic year, is approximately 220-250 million years for the Solar System. Since the beginning of its formation, the Solar System has made at least 20 revolutions around the center of the galaxy.

Many scientists believe that the passage of the solar system through the galaxy influences the frequency of mass extinctions of the animal world in the past. According to one hypothesis, the vertical oscillations of the Sun in its orbit around the galactic center, leading to the Sun regularly crossing the galactic plane, change the power of the tidal forces of the galaxy on the Solar System. When the Sun is outside the galactic disk, the influence of galactic tidal forces is less; when it returns to the galactic disk - and this happens every 20-25 million years - it is influenced by much more powerful tidal forces. This, according to mathematical models, increases the frequency of comets arriving from the Oort Cloud into the Solar System by 4 orders of magnitude, and therefore greatly increases the likelihood of global catastrophes as a result of comets falling to Earth.

However, many dispute this hypothesis, arguing that the Sun is already close to the galactic plane, but the last mass extinction was 15 million years ago. Consequently, the vertical position of the Solar system relative to the galactic plane cannot in itself explain the periodicity of mass extinctions on Earth, but it has been suggested that these extinctions may be associated with the passage of the Sun through the spiral arms of the galaxy. Spiral arms contain not only large clusters of molecular clouds, the gravity of which can deform the Oort cloud, but also large numbers of bright blue giants that live for a relatively short time, and die in supernovae, dangerous to all life nearby.

4.1. Collision of galaxies

Antenna galaxies - an example of colliding galaxies

Despite the fact that the vast majority of galaxies in the Universe are moving away from the Milky Way, the Andromeda Galaxy, which is the largest galaxy in the local group, on the contrary, is approaching it at a speed of 120 km/s. In 2 billion years, the Milky Way and Andromeda will collide, and the collision will warp both galaxies. The outer spiral arms will collapse, but "tidal tails" will form, caused by tidal interactions between galaxies. There is a 12% chance that this event will eject the Solar System from the Milky Way into its tail, and a 3% chance that Andromeda will capture the Solar System. After a series of tangent collisions, increasing the probability of the Solar System being ejected from the Milky Way to 30%, their central black holes will merge into one. After 7 billion years, the Milky Way and Andromeda will complete their merger and become one giant elliptical galaxy. During a galaxy merger, due to the increased force of gravity, interstellar gas will be intensely attracted to the center of the galaxy. If there is enough of this gas, it can lead to a so-called burst of star formation in a new galaxy. The gas falling into the center of the galaxy will actively feed the newly formed black hole, turning it into an active galactic nucleus. During this epoch, it is likely that the Solar System will be pushed into the outer halo of the new galaxy, allowing it to remain at a safe distance from the radiation of these grand collisions.

It is a common misconception that a galaxy collision will almost certainly destroy the solar system, but this is not entirely true. Despite the fact that the gravity of passing stars is quite capable of doing this, the distance between individual stars is so great that the likelihood of any star having a destructive effect on the integrity of the Solar System during a galactic collision is very insignificant. Most likely, the Solar system will be influenced by the collision of galaxies as a whole, but the arrangement of the planets and the Sun among themselves will remain undisturbed.

However, over time, the total probability for the solar system to be destroyed by the gravity of passing stars gradually increases. Assuming the Universe does not end up in a big crash or big rip, calculations predict that the solar system will be completely destroyed by passing stars in 1 quadrillion (10 15) years. In that distant future, the Sun and planets will continue their journey through the galaxy, but the Solar System as a whole will cease to exist.

Notes

The reason Saturn, Uranus, and Neptune moved outward while Jupiter moved inward is because Jupiter is massive enough to eject planetesimals out of the solar system, but these three planets are not. In order to throw the planet out of the system, Jupiter transfers part of its orbital energy to it, and therefore approaches the Sun. When Saturn, Uranus and Neptune eject planetesimals outward, these objects go into highly elliptical, but still closed orbits, and thus can return to the disturbing planets and compensate them for their lost energy. If these planets eject planetesimals into the system, this increases their energy and causes them to move away from the Sun. More importantly, an object ejected inward by these planets has a greater chance of being captured by Jupiter and then ejected out of the system, permanently locking in the excess energy received by the outer planets during the “ejection” of that object.

The origin of the solar system is directly due to gravitational forces. It is thanks to them that the Universe, galaxies, stars and planets exist. People who lived many centuries ago assumed that there must be some mysterious forces that gradually controlled the world. But the first to create a mathematical model of universal gravitation was English physicist, mathematician and astronomer Isaac Newton(1642-1727). He laid the foundations of celestial mechanics.

It was on the basis of Newton's work that Kepler's empirical laws emerged. A theory of the movement of comets and the Moon was created. Newton scientifically explained the precession of the earth's axis. All this is still considered a huge contribution to science. But the German philosopher Immanuel Kant (1724-1804) was the first to express his thoughts on the formation of the Sun and planets.

In 1755, his work “General Natural History and Theory of the Sky” was published. In it, the philosopher suggested that all celestial bodies and the star itself arose from a nebula, which was originally a huge cloud of gas and dust. Kant was the first to talk about cosmogony- the origin of the world.

This requires primary material and gravitational forces. But divine intervention is not required in this matter. That is, the world arose as a result of physical laws, and God did not take any part in this. This was quite a bold statement at the time.

Three stages of formation of the solar system

Modern views on the origin of the solar system largely coincide with Kant's conclusions. It was not for nothing that, if you believe Bulgakov, he constantly had breakfast with the Devil himself. Therefore, the philosopher knew what he was saying, and today's scientific minds largely agree with him.

The main theory suggests that on the site of the current solar system 5 billion years ago there was a giant cloud of gases and dust. It was enormous in size and stretched over 6 billion km in space. Similar dust clouds exist in many corners of the vast Universe. Their bulk consists of hydrogen. This is the gas from which stars are originally formed. Then, as a result of a thermonuclear reaction, the inert gas helium begins to be released. The share of other substances accounts for only 2%.

At some point, the dust cloud received an external powerful impulse, representing a huge release of energy. It could have been a shock wave generated by a supernova explosion. Or it is possible that there was no external influence. Simply due to the law of attraction, the cloud began to decrease in volume and become denser.

This process gave impetus to gravitational collapse. That is, a rapid compression of cosmic mass occurred. As a result, a hot core with a very high density appeared in the center. The rest of the mass was dispersed along the edges of the core. And since everything in space rotates around its axis, this mass has acquired the shape of a disk.

The core decreased in size, increasing its temperature and density. As a result, it transformed into protostar. This is the name of a star in which the prerequisites exist for the start of a thermonuclear reaction. And the gas cloud around the core became increasingly denser.

Finally, the temperature and pressure in the core reached a critical value. This triggered the start of a thermonuclear reaction, and hydrogen began to turn into helium. The protostar ceased to exist, and in its place a star called the Sun arose. This whole process lasted about one million years. By cosmic standards, quite a bit.

But then another process began. Gas and dust clouds revolving around the Sun began to gather into dense rings. In each of them a clot with a higher density was formed. Moreover, the heaviest substances ended up in the center of the clot, and the light ones created the outer shell. This is how the cores of the planets were formed, surrounded by gases.

To put it quite simply, we can say that the star “blew away” gas shells from the nearest cores. This is how small planets were formed, orbiting near the Sun. This Mercury, Venus, Earth and Mars. And other planets were at a great distance from the star. That's why they kept their "gas coats". They are currently known as the gas giant planets: Jupiter, Saturn, Uranus and Neptune. All these transformations took another 4 million years.

Subsequently, satellites appeared around the planets. This is how the Moon appeared near the Earth. The rest of the planets also acquired satellites. And, in the end, a single space community was formed, which exists to this day.

This is how science explains the origin of the solar system. By the way, this theory is also inherent in other stellar formations, of which there are an infinite number in space. Who knows, maybe somewhere in the black abyss there is a star system similar to ours. There is intelligent life there, and, therefore, there is some kind of civilization. It is quite possible that someday people will meet brothers in mind. This will be the most outstanding event in our history.

Not one of the large number of different models of the origin and development of the solar system has been promoted to the rank of a generally accepted theory.

According to Kant–Laplace hypothesis The system of planets around the Sun was formed as a result of the forces of attraction and repulsion between particles of scattered matter in rotational motion around the Sun.

For the first time, an English physicist and astrophysicist J. H. Jeans(1877 - 1946) suggested that the Sun once collided with another star, as a result of which a stream of gas was torn out of it, which, condensing, turned into planets. Given the enormous distance between the stars, such a collision seems incredible.

Of the modern hypotheses of the origin of the Solar system, the most famous is the electromagnetic hypothesis of the Swedish astrophysicist H. Alfvena (1908 - 1995)and English F. Hoyle (1915 - 2001). According to this theory, the original gas cloud from which both the Sun and the planets were formed consisted of ionized gas subject to the influence of electromagnetic forces. After the Sun was formed from a huge gas cloud through concentration, small parts of this cloud remained at a very large distance from it. The gravitational force began to attract the remaining gas to the resulting star - the Sun, but its magnetic field stopped the moving gas at various distances - exactly where the planets are located. Gravitational and magnetic forces influenced the concentration and thickening of this gas. As a result, planets were formed. When the largest planets arose, the same process was repeated on a smaller scale, thus creating satellite systems.

The hypothesis of the formation of the Solar system from a cold gas and dust cloud surrounding the Sun, proposed by a Soviet scientist, is also known O.Yu. Schmidt (1891 - 1956).

According to the currently generally accepted hypothesis, the formation of the Solar System began about 4.6 billion years ago with the gravitational collapse of a small part of a giant interstellar gas and dust cloud. This initial cloud was probably several light years in size and was the progenitor of several stars.

During the process of gravitational compression, the size of the gas and dust cloud decreased and, due to the law of conservation of angular momentum, the speed of rotation of the cloud increased. The center, where most of the mass had gathered, became hotter and hotter than the surrounding disk. Due to the rotation, the compression rates of the clouds parallel and perpendicular to the rotation axis differed, which led to the flattening of the cloud and the formation of a characteristic protoplanetary disk with a diameter of approximately 200 AU. and a hot, dense protostar at the center. It is believed that at this point in its evolution the Sun was a T Tauri star. Study of such stars shows that they are often accompanied by protoplanetary disks with masses of 0.001 - 0.1 solar masses, with the overwhelming percentage of the nebula's mass concentrated directly in the star. The planets were formed by accretion from this disk (Fig. 27).

Over the course of 50 million years, the pressure and density of hydrogen at the center of the protostar became high enough for thermonuclear reactions to begin. Temperature, reaction rate, pressure and density increased until hydrostatic equilibrium was achieved, with thermal energy opposing the force of gravitational compression. At this stage, the Sun became a full-fledged main sequence star.

Fig. 27 Evolution of the Sun

The solar system will exist until the Sun begins to evolve outside the main sequence of the Hertzsprung-Russell diagram, which shows the relationship between the brightness of stars and their surface temperature. Hotter stars are more luminous.

The Sun burns its reserves of hydrogen fuel, and the released energy tends to be depleted, causing the Sun to shrink. This increases the pressure in its depths and heats the core, thus accelerating the combustion of fuel. As a result, the Sun becomes brighter by about ten percent every 1.1 billion years.

In about 5 to 6 billion years, the hydrogen in the Sun's core will be completely converted to helium, ending the main sequence phase. At this time, the outer layers of the Sun will expand approximately 260 times - the Sun will become a red giant. Due to the extremely increased surface area, it will be much cooler than when on the main sequence (2600 K).

Ultimately, the outer layers of the Sun will be thrown into the surrounding space by a powerful explosion, forming a planetary nebula, in the center of which only a small stellar core will remain - a white dwarf, an unusually dense object with half the original mass of the Sun, but the size of the Earth. This nebula will return some of the material that formed the Sun into the interstellar medium.

Theories of the origin of the Solar system are hypothetical in nature, and it is impossible to unambiguously resolve the issue of their reliability at the present stage of scientific development. All existing theories have contradictions and unclear areas.

The lack of a generally accepted version of the origin of the planetary system has its own explanation. First of all, the uniqueness of the object of observation excludes the use of comparative analysis and forces us to solve the difficult task of reconstructing history based only on knowledge about the current state of the Solar system. For example, ideas about the evolution of stars from their birth to death were obtained through the accumulation and statistical processing of observed data on the current state of many stars of different classes, at different stages of development. It is not surprising that astronomy knows much more about the development of stars far from us than about the origin and development of our habitat - the Solar System.

Thus, the solar system is a very complex natural formation, combining the diversity of its constituent elements with the highest stability of the system as a whole. Given the huge number and variety of elements that make up a system, and the complex relationships that are established between them, the task of determining the mechanism of its formation turns out to be very difficult.

The Solar System includes:

· Sun;

· 4 terrestrial planets: Mercury, Venus, Earth, Mars and their satellites;

· the belt of minor planets - asteroids, which includes the dwarf planet Ceres;

· countless number of meteorite bodies, moving both in swarms and singly.

· 4 giant planets: Jupiter, Saturn, Uranus, Neptune and their satellites;

· hundreds of comets;

· centaurs;

· trans-Neptunian objects: the Kuiper belt, which includes 4 dwarf planets: Pluto, Haumea, Makemake, Eris and the scattered disk;

· Remote areas that include the Oort and Sedna clouds;

· Border areas.

Sun

The Sun belongs to the ordinary stars of our Galaxy and is a hot gas (plasma) ball of predominantly helium-hydrogen composition, which is diluted with an admixture (about 1%) of other chemical elements, the ratio of which varies from the surface to the core. The upper layers of the Sun contain about 90% hydrogen and 10% helium. The core contains only 37% hydrogen. The ratio between hydrogen and helium changes over time in favor of helium, since thermonuclear reactions have been occurring on the Sun for 4.5 billion years, transforming hydrogen nuclei into helium nuclei. Every second, about 600 million tons of hydrogen are converted into helium at a temperature of about 15 million 0 C. At the same time, 4.3 million tons are converted into radiant energy (Fig. 28).

The retelling of the story of the birth of our solar system has been very monotonous for many years. It all began billions of years ago with a dark and slowly rotating cloud of gas and dust. The cloud contracted, forming the Sun at its center. Over time, eight planets and many smaller bodies such as . Since then, the planets have been circling the Sun and their movements are as precise and predictable as a clockwork.

Recently, astronomers have been discovering facts that refute this old tale. Compared to the design of the thousands of recently discovered exoplanet systems, the most characteristic features of our solar system - its inner rocky planets, outer gas giants and the absence of planets within the orbit of Mercury - look rather strange. By simulating the past on computers, we see that these quirks were the product of a wild youth. The history of the solar system needs to be rewritten to include far more drama and chaos than most of us expected.

The new version of the story tells of wandering planets driven from their homes, of lost worlds that perished long ago in the fiery inferno of the Sun, and of lonely giants abandoned in the cold depths at the edge of interstellar space. By studying these ancient events and the “scars” they left behind, such as a proposed ninth planet that may be hiding beyond the orbit of Pluto, astronomers are building a coherent picture of the most important formative eras of the solar system against the backdrop of a new understanding of cosmic processes.

Classical Solar System

Planets are a by-product of star formation, which occurs in the depths of giant molecular clouds that exceed our Sun in mass by 10 thousand times. Individual densities in the cloud are compressed under the influence of gravity, forming a luminous protostar at its center, surrounded by a wide opaque ring of gas and dust - a protoplanetary disk.

For many decades, theorists have modeled the protoplanetary disk of our Sun, trying to explain one of the most important features of the Solar System: its division into groups of rocky and gas planets. The orbital periods of the four Earth-like planets fall between the 88-day Mercury and the 687-day Mars. In contrast, the known gas giants are in much more distant orbits with periods ranging from 12 to 165 years and together have more than 150 times the mass of terrestrial planets.

Both types of planets are believed to have been born in a single formation process in which solid grains of dust, racing in the turbulent vortex of a gas disk, collided and stuck together to form kilometer-scale bodies called planetesimals (much like on the unswept floor of your kitchen, air currents and electrostatic forces roll up dust particles). balloons). The largest planetesimals had the greatest gravitational pull and grew faster than others, attracting small particles into their orbit. Probably over the course of a million years, in the process of being compressed from the cloud, the protoplanetary disk of our Solar System, like any other in the Universe, was teeming with planetary embryos the size of the Moon.

The largest embryo was located just beyond the modern asteroid belt, far enough from the light and heat of the newborn Sun, where ice was preserved in the protoplanetary disk. Beyond this “ice boundary,” embryos could feast on abundant deposits of planet-building ice and grow to enormous sizes. As usual, “the rich get richer”: the largest embryo grew faster than the others, scooping out most of the available ice, gas and dust from the surrounding disk with its gravitational field. In just about a million years, this greedy embryo grew so large that it became the planet Jupiter. This was the decisive moment, theorists thought, when the architecture of the solar system split in two. Left behind Jupiter, the other giant planets of the solar system turned out to be smaller because they grew more slowly, capturing with their gravity only the gas that Jupiter did not have time to capture. And the inner planets turned out to be even much smaller, since they were born inside the ice boundary, where the disk was almost devoid of gas and ice.

Exoplanetary revolution

When astronomers began discovering exoplanets two decades ago, they began testing theories of solar system formation on a galactic scale. Many of the first exoplanets discovered turned out to be “hot Jupiters,” that is, gas giants that rapidly orbit their stars with periods of only a few days. The existence of giant planets so close to the blazing surface of a star, where ice is completely absent, completely contradicts the classical picture of planet formation. To explain this paradox, theorists have proposed that hot Jupiters form far away and then somehow migrate inward.

Moreover, based on data from thousands of exoplanets discovered in surveys such as those from NASA's Kepler Space Telescope, astronomers have come to the alarming conclusion that Solar System twins are quite rare. The average planetary system contains one or more super-Earths (planets several times larger than Earth) with orbital periods shorter than about 100 days. And giant planets like Jupiter and Saturn are found in only 10% of stars, and even less often do they move in almost circular orbits.

Disappointed in their expectations, the theorists realized that “several important details” of the classical theory of the formation of our planetary system required a better explanation. Why is the inner Solar System so low-mass compared to its exoplanet counterparts? Instead of super-Earths, it has small, rocky planets, and none within Mercury's 88-day orbit. And why are the orbits of the giant planets near the Sun so round and wide?

Obviously, the answers to these questions lie in the shortcomings of the classical theory of planet formation, which does not take into account the variability of protoplanetary disks. It turns out that a newborn planet, like a life raft in the ocean, can drift far from its birthplace. After the planet has grown, its gravity begins to influence the surrounding disk, exciting spiral waves in it, the gravity of which already affects the movement of the planet itself, creating powerful positive and negative feedbacks between the planet and the disk. As a result, an irreversible exchange of momentum and energy can occur, allowing young planets to embark on an epic journey across their parent disk.

If we take into account the process of planetary migration, then the boundaries of the ice within the disks no longer play a special role in the formation of the structure of planetary systems. For example, giant planets born beyond the ice boundary can become hot Jupiters by drifting towards the center of the disk, that is, traveling along with gas and dust in a spiral towards the star. The trouble is that this process works too well and seems to occur in all protoplanetary disks. Then how to explain the distant orbits of Jupiter and Saturn around the Sun?

Change of tack

The first hint of a convincing explanation came in 2001 from a computer model by Frederic Masset and Mark Snellgrove of Queen Mary University of London. They simulated the simultaneous evolution of the orbits of Saturn and Jupiter in the protoplanetary disk of the Sun. Because of Saturn's smaller mass, its migration toward the center is faster than that of Jupiter, causing the orbits of the two planets to move closer together. Eventually the orbits reach a certain configuration known as mean motion resonance, in which Jupiter orbits the Sun three times for every two orbital periods of Saturn.

Two planets connected by mean motion resonance can exchange momentum and energy back and forth with each other, much like an interplanetary game of hot potato tossing. Due to the coordinated nature of resonant disturbances, both planets exert an enhanced gravitational influence on each other and on their surroundings. In the case of Jupiter and Saturn, this “swing” allowed them to collectively influence the protoplanetary disk with their mass, creating a large gap in it with Jupiter on the inside and Saturn on the outside. Moreover, due to its greater mass, Jupiter attracted the inner disk more strongly than Saturn, the outer one. Paradoxically, this caused both planets to change their motion and begin to move away from the Sun. Such a sharp change in the direction of migration is often called a change of tack (the grand tack) due to its similarity to the movement of a tacking sailboat going against the wind.

In 2011, ten years after the tack change concept was born, a computer model by Kevin J. Walsh and his colleagues at the Côte d'Azur Observatory in Nice, France, showed that the idea does a good job of explaining more than just the dynamical history of Jupiter and Saturn , but also the distribution of rocky and icy asteroids, as well as the low mass of Mars. As Jupiter migrated inward, its gravitational influence captured and moved planetesimals on its way through the disk, scooping and pushing them forward like a bulldozer. If we assume that Jupiter, before turning back, migrated towards the Sun to the distance of the current orbit of Mars, then it could drag ice blocks with a total mass of more than ten Earth masses into the region of the Earth-like planets of the solar system, enriching it with water and other volatile substances. The same process could have created a clear outer boundary at the inner part of the protoplanetary disk, stopping the growth of the nearby planetary embryo, which eventually became what we call Mars today.

Jupiter attack

While the 2011 tack scenario was compelling, its relevance to other unsolved mysteries of our solar system, such as the complete absence of planets within Mercury's orbit, remained unclear. Compared to other planetary systems where super-Earths are densely packed, ours seems almost empty. Has our solar system really missed the critical stage of planet formation that we see throughout the universe? In 2015, two of us (Konstantin Batygin and Gregory Laughlin) looked at how a tack change might affect a hypothetical group of super-Earths close to the Sun. Our conclusion was astonishing: super-Earths would not have survived the tack change. It is remarkable that the migrations of Jupiter in and out can explain many of the properties of the planets that we know, as well as those that are unknown.

As Jupiter plunged into the inner solar system, its bulldozing influence on the planetesimals would disrupt their neat circular orbits, turning them into a chaotic tangle of intersecting trajectories. Some planetesimals must have collided with great force, breaking into fragments that inevitably caused further collisions and destruction. Thus, Jupiter's inward migration likely triggered a cascade of impacts that destroyed the planetesimals, grinding them down to the size of boulders, pebbles, and sand.

Under the influence of collisional friction and aerodynamic drag in the gassed inner region of the protoplanetary disk, the destroyed planetesimals quickly lost their energy and spiraled closer to the Sun. During this fall, they could easily be captured in new resonances associated with any of the super-Earths close to them.

Thus, the tack change of Jupiter and Saturn may have caused a powerful attack on the population of the primordial inner planets of the solar system. As the former super-Earths fell into the Sun, they would have left behind a desolate region in the protoplanetary nebula, extending to orbital periods of about 100 days. As a result, Jupiter's rapid maneuver through the young Solar System led to the appearance of a rather narrow ring of rocky debris, from which the terrestrial planets formed hundreds of millions of years later. The confluence of chance events that led to this delicate choreography indicates that small, rocky planets like Earth—and perhaps even life on them—should be rare in the universe.

Nice model

By the time Jupiter and Saturn headed back from their foray into the inner Solar System, the protoplanetary disk of gas and dust had already been severely depleted. Eventually the resonant pair of Jupiter and Saturn came close to the newly formed Uranus and Neptune, and possibly another body of similar size. Using the gravitational braking effects in the gas, the dynamic duo also captured these smaller giants into resonances. Thus, when most of the gas left the disk, the inner architecture of the Solar System likely consisted of a ring of rocky debris in the vicinity of Earth's current orbit.

In the outer region of the system there was a compact, resonant group of at least four giant planets moving in nearly circular orbits between the present orbit of Jupiter and about half the distance to the present orbit of Neptune. In the outer part of the disk, beyond the orbit of the outermost giant planet, at the far cold edge of the solar system, icy planetesimals moved. Over hundreds of millions of years, the terrestrial planets formed, and the once restless outer planets settled into a state that could be called stable. However, this was not yet the final stage in the evolution of the Solar System.

The change of tack and the attack of Jupiter caused the last burst of interplanetary violence in the history of the Solar System, applied the final touch that brought the planetary retinue of our Sun almost to the configuration that we see today. This final episode, called the late heavy bombardment, occurred between 4.1 and 3.8 billion years ago, when the solar system temporarily turned into a shooting gallery. filled with many colliding planetesimals. Today, the scars from their impacts are visible as craters on the surface of the Moon.

Working with several colleagues at the Côte d'Azur Observatory in Nice in 2005, one of us (Alessandro Morbidelli) created the so-called Nice model to explain how interactions between giant planets could have caused the late heavy bombardment. Where the tack ends, the Nice pattern begins.

The giant planets located close to each other were still moving in mutual resonance and still felt the weak gravitational influence of the outlying icy planetesimals. In fact, they were teetering on the brink of instability. Accumulating over millions of orbital revolutions over hundreds of millions of years, each individually insignificant influence of the outer planetesimals little by little changed the motion of the giants, slowly removing them from the delicate balance of resonances that connected them with each other. The turning point came when one of the giants fell out of resonance with the other, thereby upsetting the balance and triggering a series of mutual chaotic disturbances of the planets, which shifted Jupiter slightly inward of the system, and the remaining giants outward. Over a cosmically short period of several million years, the outer region of the Solar System experienced a sharp transition from a densely packed, almost circular orbit to a diffuse and disordered configuration with planets moving in wide, elongated orbits. The interaction between the giant planets was so strong that one or even several of them may have been thrown far beyond the solar system into interstellar space.

If dynamic evolution stopped there, then the structure of the outer regions of the Solar System would correspond to the picture that we see in many exoplanetary systems, where giants move around their stars in eccentric orbits. Fortunately, the disk of icy planetesimals that had previously caused disorder in the motion of the giant planets later helped eliminate it by interacting with their elongated orbits. Passing close to Jupiter and other giant planets, planetesimals gradually took away the energy of their orbital motion and thereby rounded their orbits. In this case, most of the planetesimals were thrown out of the gravitational influence of the Sun, but some remained in associated orbits, forming a disk of icy “garbage”, which we now call the Kuiper Belt.

Planet Nine: The Definitive Theory

Persistent observations at the largest telescopes are gradually revealing to us the vastness of the Kuiper Belt, demonstrating its unexpected structure. In particular, astronomers noticed a peculiar distribution of the most distant ones moving at the outer boundaries of the viewing area. Despite the large difference in distances from the Sun, the orbits of these objects are tightly grouped, as if they were all experiencing a common and very strong disturbance. Computer simulations by Batygin and Michael E. Brawn of the California Institute of Technology showed that such a picture could be created by a hitherto undetected object with a mass ten times greater than Earth, moving in a highly eccentric orbit around the Sun. with a period of about 20 thousand years. It is unlikely that such a planet could have formed so far away, but its appearance there can be quite easily understood if it was thrown there during the youth of the Solar System.

If the existence of the ninth planet is confirmed, this will sharply strengthen the restrictions on the picture of the evolution of our strange - with a “hole” in the center - Solar system and will put new demands on a theory that could explain all its features. Astronomers are now using Earth's largest telescopes to try to find this mysterious planet. Its discovery would complete the penultimate chapter in the long and complex story of how we have tried to understand our place in the universe. And this story will end only when we finally find planets with life orbiting other stars.

Just as DNA sequencing reveals the history of humanity's ancient migrations across the surface of our small planet, computer simulations are allowing astronomers to reconstruct the magnificent history of planetary travel over the billions of years of the solar system. From its birth in a dark molecular cloud to the formation of the first planets, to the devastating events of tack changes, the attack of Jupiter and the Nice model, to the emergence of life and consciousness near at least one of the stars in the vastness of the Milky Way, the complete biography of our solar system will be one of the most significant advances in modern science - and undoubtedly one of the greatest stories ever told.

Material from Wikipedia and video (film by US Flight 33 Productions and Workaholic Productions).

According to modern ideas, formation of the solar system began about 4.6 billion years ago with the gravitational collapse of a small part of a giant interstellar molecular cloud. Most of the matter ended up in the gravitational center of the collapse with the subsequent formation of the solar star. The matter that did not fall into the center formed a protoplanetary disk rotating around it, from which planets, their satellites, asteroids and other small bodies of the Solar System were subsequently formed.

The hypothesis about the formation of the Solar system from a cloud of gas and dust - the nebular hypothesis - was originally proposed in the 18th century by Emmanuel Swedenborg, Immanuel Kant and Pierre-Simon Laplace. Its further development took place with the participation of many scientific disciplines, including astronomy, physics, geology and planetary science. With the advent of the space age in the 1950s, and with the discovery of planets outside the solar system (exoplanets) in the 1990s, this model has undergone many tests and improvements to explain new data and observations.

In general terms, the process of forming our system can be described as follows:
The trigger for the gravitational collapse was a small (spontaneous) compaction of the substance of the gas and dust cloud (possible reasons for which could be both the natural dynamics of the cloud and the passage of a shock wave from a supernova explosion through the substance of the cloud, etc.), which became the center of gravitational attraction for the surrounding substance - the center of gravitational collapse. The cloud already contained not only primordial hydrogen and helium, but also numerous heavy elements (Metallicity) left over from stars of previous generations. In addition, the collapsing cloud had some initial angular momentum.
During the process of gravitational compression, the size of the gas and dust cloud decreased and, due to the law of conservation of angular momentum, the speed of rotation of the cloud increased. Due to the rotation, the compression rates of the clouds parallel and perpendicular to the rotation axis differed, which led to the flattening of the cloud and the formation of a characteristic disk.
As a consequence of compression, the density and intensity of collisions of particles of matter with each other increased, as a result of which the temperature of the substance continuously increased as it was compressed. The central regions of the disk heated up most strongly.
When the temperature reached several thousand Kelvin, the central region of the disk began to glow - a protostar formed. Matter from the cloud continued to fall onto the protostar, increasing the pressure and temperature at the center. The outer regions of the disk remained relatively cold. Due to hydrodynamic instabilities, individual compactions began to develop in them, which became local gravitational centers for the formation of planets from the matter of the protoplanetary disk.

Terrestrial planets

A giant collision of two celestial bodies, possibly giving birth to the Earth's satellite, the Moon.
At the end of the era of planet formation, the inner Solar System was populated by 50-100 protoplanets with sizes ranging from lunar to Martian. Further growth in the size of celestial bodies was due to collisions and mergers of these protoplanets with each other. For example, as a result of one of the collisions, Mercury lost most of its mantle, while as a result of another, the Earth's satellite, the Moon, was born. This phase of collisions continued for about 100 million years until there were only 4 massive celestial bodies now known in orbit.

One of the unresolved problems with this model is the fact that it cannot explain how the initial orbits of protoplanetary objects, which had to be highly eccentric to collide with each other, could end up giving rise to stable and nearly circular orbits of the remaining four planets. According to one hypothesis, these planets were formed at a time when interplanetary space still contained a significant amount of gas and dust material, which, due to friction, reduced the energy of the planets and made their orbits smoother. However, this same gas should have prevented the occurrence of large elongations in the initial orbits of the protoplanets. Another hypothesis suggests that the correction of the orbits of the inner planets occurred not due to interaction with gas, but due to interaction with the remaining smaller bodies of the system. As large bodies passed through a cloud of small objects, the latter, due to gravitational influence, were drawn into regions of higher density, and thus created “gravitational ridges” along the path of large planets. The increasing gravitational influence of these "ridges", according to this hypothesis, caused the planets to slow down and enter a more rounded orbit.

Late heavy bombardment

The gravitational collapse of the ancient asteroid belt likely initiated a period of heavy bombardment that occurred about 4 billion years ago, 500-600 million years after the formation of the solar system. This period lasted several hundred million years and its consequences are still visible on the surface of geologically inactive bodies of the Solar System, such as the Moon or Mercury, in the form of numerous impact craters. And the oldest evidence of life on Earth dates back to 3.8 billion years ago - almost immediately after the end of the Late Heavy Bombardment period.

Formation of satellites
Natural satellites have formed on most of the planets in the Solar System, as well as on many other bodies. There are three main mechanisms of their formation:

Formation from a circumplanetary disk (in the case of gas giants)
formation of collision fragments (in the case of a sufficiently large collision at a low angle)
capture of a flying object
Jupiter and Saturn have many moons, such as Io, Europa, Ganymede and Titan, which probably formed from the disks around these giant planets in the same way that these planets themselves formed from the disk around the young Sun. This is indicated by their large size and proximity to the planet. These properties are impossible for satellites acquired through capture, and the gaseous structure of the planets makes the hypothesis of the formation of moons through a collision of a planet with another body impossible.

Lecture 6.3 | Evolution of planetary systems. Origin of planets and their satellites | Vladimir Surdin Lectorium Published: May 31, 2016

Surdin - Vladimir Georgievich Surdin (born April 1, 1953, Miass) - Soviet and Russian astronomer and popularizer of science. Candidate of Physical and Mathematical Sciences, Associate Professor. Senior researcher at the State Astronomical Institute named after P. K. Sternberg, associate professor at the Faculty of Physics of Moscow State University. Winner of the Belyaev Prize and the Enlightener Prize for 2012. Vladimir Surdin is the author and editor of several dozen popular science books on astronomy and astrophysics, as well as many popular science articles, essays and interviews. He was awarded the Belyaev Prize for a series of popular science articles. Gives popular lectures at the Polytechnic Museum. , is a member of the editorial board of its printed organ - the RAS bulletin “In Defense of Science”.

Surdin's page with all published books and lectures that participate in several of the largest all-Russian educational projects. http://lnfm1.sai.msu.ru/~surdin/

There are also documentaries in the series Universe (2007-2012) 7 seasons.
The program was created by US companies Flight 33 Productions and Workaholic Productions.
Season 6, episode 3, 2011. How the solar system was created All previous copies and links to episode lists have stopped working, and the video materials have been blocked by copyright holders. Well, they are significantly outdated, although it was a beautiful, mostly cartoon movie for children (animation simulating the movement of solar system objects is about 80%). Anyone who wants can search by title, I’m just tired of running through the book and erasing yet another missing video. It looks like from this film the supposed mechanism of the formation of a red giant and a white dwarf in the future evolution of our Sun, views at the time of approximately 2010, since then they seem to have changed little on these issues

Stages of formation of the solar system and earth. How the solar system began. Problems in studying the formation of the Solar System

Plan:

Introduction

1. Formation