The formation and evolution of the Solar System began 4.6 billion years ago with the collapse of gravity from a small part of a gigantic molecular cloud. Most collapsed mass collected in the center, forming the Sun, while the rest flattened into a protoplanet disk from which planets, moons, asteroids, and other small Solar System bodies formed.
This model, known as the nebular hypothesis and now refined as the Nice model (2005), was first developed in the 18th century by Emanuel Swedenborg, Immanuel Kant, and Pierre-Simon Laplace. Further developments have been interwoven various disciplines including astronomy, physics, geology, and planetary science. Since the beginning of the space era in the 1950s and the discovery of solar outer planets in the 1990s, the model has been challenged and perfected to account for new observations.
The Solar System has grown tremendously since its inception. Many moons are formed from gas and dust discs around their parent planets, while other moons are thought to be formed independently and then captured by their planets. Others, like Earth's Moon, may be the result of a giant collision. Collision between bodies has been ongoing to this day and has been the center of the evolution of the Solar System. The position of planets often shifts due to gravitational interactions. The migration of the planet is now considered responsible for much of the early evolution of the Solar System.
In about 5 billion years, the Sun will cool and widen to many times its present diameter (into a red giant), before releasing its outer layer as a planetary nebula and leaving the rest of the star known as a white dwarf. In the distant future, the gravity of the passing stars will gradually reduce the retinue of the planets of the Sun. Some planets will be destroyed, others expelled into interstellar space. In the end, for tens of billions of years, it is possible that the Sun will be abandoned without any native bodies in orbit around it.
Video Formation and evolution of the Solar System
Histori
Ideas about the origin and fate of the world's date of the earliest known writings; however, most of the time, there is no attempt to relate such theories to the existence of the "Solar System", simply because it is not generally assumed that the Solar System, in the sense we now understand, exists. The first step towards the theory of the formation and evolution of the Solar System is the general acceptance of heliocentrism, which places the Sun at the center of the system and Earth in orbit around it. This concept has evolved over the centuries (Aristarchus of Samos has suggested it as early as 250 BC), but it was not widely accepted until the end of the 17th century. The first recorded use of the term "Solar System" comes from 1704.
The current standard theory for the formation of the Solar System, the nebular hypothesis, has fallen into and is not favored since its formulation by Emanuel Swedenborg, Immanuel Kant, and Pierre-Simon Laplace in the 18th century. The most significant criticism of the hypothesis is its apparent inability to explain the lack of relative Sun angular momentum when compared to the planets. However, since the early 1980s studies of young stars have shown them surrounded by cold disks of dust and gas, just like the predicting nebular hypothesis, which has led to re-acceptance.
An understanding of how the Sun is expected to continue to evolve requires an understanding of the source of its power. The recognition of Albert Einstein's theory of relativity by Arthur Stanley Eddington led to his realization that the energy of the Sun comes from a nuclear fusion reaction at its core, combining hydrogen into helium. In 1935, Eddington went further and suggested that other elements may also be formed in stars. Fred Hoyle outlines this premise by arguing that the evolved stars called the red giants create many elements heavier than hydrogen and helium at their core. When the red giant finally blows its outer layers, these elements will then be recycled to form other star systems.
Maps Formation and evolution of the Solar System
Formation
Pre-sun nebula
The nebular hypothesis says that the Solar System is formed from the gravitational collapse of a fragment of a gigantic molecular cloud. The cloud was about 20 parsec (65 light years), while the fragment was about 1 parsec (three and a quarter light years). Further collapse of the fragments causes the formation of a solid core of 0.01-0.1 pc (2000-20000 AU) in size. One fragment of collapse (known as pre-solar nebula) forms what is the Solar System. The composition of this region with the mass of more than the Sun ( M ? ) is similar to today's sun, with hydrogen, along with helium and trace the amount of lithium produced by Big Bang nucleosynthesis, forming about 98% of its mass. The remaining 2% of the mass consists of heavier elements created by nucleosynthesis in the early generations of stars. At the end of the lives of these stars, they release the heavier elements to the interstellar medium.
The oldest inclusions found in meteorites, which allegedly tracked the first solid material formed in pre-solar nebula, were 4568.2 million years old, which is one of the definitions of the age of the Solar System. Ancient meteorite studies reveal traces of the daughter's stable, short-lived isotope nuclei, such as the 60-iron, formed only in explosions, short stars. This suggests that one or more supernovae occur near the Sun when it is formed. The shock wave from the supernova may have triggered the formation of the Sun by creating a relatively dense area within the cloud, causing these areas to collapse. Since only large and short-lived stars produce supernovae, the Sun must have formed in the large star-forming regions that produce large stars, which may be similar to the Orion Nebula. The study of the structure of the Kuiper belt and the anomalous material in it shows that the Sun is formed in groups between 1,000 and 10,000 stars with diameters between 6.5 â € <â €
Due to the conservation of angular momentum, the nebula spins faster as it collapses. When the material inside the nebula is thick, the atoms inside begin to collide with increasing frequency, converting their kinetic energy into heat. The center, where most of the mass collected, gets hotter than the disk around it. Over 100,000 years of age, competing gravitational forces, gas pressure, magnetic field, and rotation cause the contracting nebula to flatten to a protoplanetary disk rotating with a diameter of about 200 AU and form a hot and dense protostar (the star where hydrogen fusion has not yet begun) in center.
At this point in its evolution, the Sun is considered a T-Tauri star. Studies of T Tauri stars show that they are often accompanied by pre-planetary material discs with mass of 0.001-0.1 M ? . These discs extend up to several hundred AUs - the Hubble Space Telescope has observed protoplanet disks up to 1000Ã, AU in diameter in star-forming regions such as the Orion Nebula - and rather cold, reaching a surface temperature of only about 1000 kelvins. in their hottest. In 50 million years, the temperature and pressure at the core of the Sun become so large that hydrogen begins to converge, creating an internal energy source that opposes the gravitational contraction until the hydrostatic equilibrium is reached. This marks the entry of the Sun into the main phase of its life, known as the main sequence. The main sequence stars derive energy from the fusion of hydrogen to helium at their nucleus. The sun remains the star of the main sequence today.
The formation of planets
Various planets are thought to form from the solar nebula, the disk-shaped gas cloud and the dust remaining from the Sun formation. The currently accepted method in which the planets are formed is the accretion, in which the planets begin as dust grains in orbit around the center of the protostar. Through direct contact, these granules form into clumps up to 200 meters in diameter, which in turn collide to form larger bodies (planetesimal) measuring ~ 10 kilometers (km). This gradually increased through further collisions, growing at a centimeter rate per year over the next few million years.
The inner Solar System, the Solar System region in 4 AU, is too warm for volatile molecules such as water and methane to condense, so the planetesimal formed there can only be formed from compounds with high melting points, such as metals (such as iron). , nickel, and aluminum) and rocky silicates. These rocky bodies will become terrestrial planets (Mercury, Venus, Earth, and Mars). These compounds are quite rare in the universe, which comprises only 0.6% of the mass of the nebula, so terrestrial planets can not grow very large. The terrestrial embryo grows about 0.05 Earth masses ( M ? ) and ceases to accumulate matter about 100,000 years after the formation of the Sun; collisions and subsequent merging between bodies the size of the planet allows terrestrial planets to grow to their present size (see Terrestrial planet below).
When terrestrial planets are formed, they remain immersed in the gas and dust disks. The gas is partially supported by pressure and does not orbit the Sun as fast as planets. The resulting resistance and, more importantly, the gravitational interaction with surrounding material causes the transfer of angular momentum, and as a result the planets gradually migrate into new orbits. The model shows that the density and temperature variation in the disk regulates this migration rate, but the net trend is for inner planets to migrate inward as scattered disks, leaving the planets in their current orbits.
The giant planets (Jupiter, Saturn, Uranus, and Neptune) form further beyond the frozen line, which is the point between the orbits of Mars and Jupiter where the material is cool enough for volatile ice compounds to stay solid. The ice that forms the Jovian planet is more abundant than the metals and silicates that form terrestrial planets, allowing huge planets to grow large enough to capture hydrogen and helium, the lightest and most abundant element. Planetesimal outside the frost line accumulates to 4 M ? in about 3 million years. Today, four giant planets comprise just under 99% of all the mass orbiting the Sun. Theorists believe it is no coincidence that Jupiter is outside the frozen line. Because the frost line collects large amounts of water through evaporation from the infalling ice material, it creates a low pressure region that increases the speed of the dust particles orbiting and stopping their movement toward the Sun. As a result, the frost line acts as a barrier that causes the material to accumulate rapidly in ~ 5 AU from the Sun. This excess material fused into a large embryo (or core) in the order of 10 M ? , which starts collecting envelopes through increasing gas from surrounding disks at an ever-increasing rate. After the mass of the envelope becomes equal to the mass of the solid core, the growth progresses very rapidly, reaching about 150 Earth masses ~ 10 5 years later and finally reaching at 318 M ? . Saturn can owe substantially lower just to form several million years after Jupiter, when there is less gas available for consumption.
The T Tauri star like the young sun has a much stronger star wind than a more stable and older star. Uranus and Neptune are thought to have formed after Jupiter and Saturn did so, when strong solar winds have thrown away most of the disk material. As a result, the planets collect a little hydrogen and helium - no more than 1 M ? respectively. Uranus and Neptune are sometimes referred to as failing nuclei. The main problem with the formation theory for these planets is the time scale of their formation. At the current location, it will take millions of years for their core to be accommodated. This means that Uranus and Neptune may have formed closer to the Sun - close or even between Jupiter and Saturn - and then migrate or be excluded (see Planetary migration below). The motion in the planetesimal era is not entirely toward the Sun; The retarded Stardust samples from Comet Wild 2 have suggested that materials from the early formation of the Solar System migrate from the warmer inner Solar System to the Kuiper belt region.
After between three and ten million years, the Sun's solar wind will clear all the gas and dust on the protoplanet disk, blowing it into the interstellar space, ending the growth of the planets.
Next evolution
The planets were originally thought to have formed in or near their current orbit. From that the minimum mass of the nebula is the protoplanet disk, derived necessary to form planets - the minimum solar mass nebula. It originated that the mass of the nebula must exceed 3585 times that of Earth.
However, this has been questioned for the past 20 years. Today, many planetary scientists think that the Solar System may look very different after its initial formation: some objects at least as big as Mercury present in the inner Solar System, the outer Solar System is much more compact than it is now, and the Kuiper Belt is closer to the Sun.
terrestrial planets
At the end of the planet's formation era, the inner Solar System is inhabited by 50-100-month-old planetary embryos to Mars. Further growth is possible only because these bodies collide and join, which takes less than 100 million years. These objects gravitate by interacting with each other, drawing orbits to each other until they collide, grow larger until the four terrestrial planets we know are now formed. One such massive collision is thought to have formed the Moon (see Moon below), while the other pulls out a young Mercury outer envelope.
One unresolved problem with this model is that it can not explain how the early orbits of proto-terrestrial planets, which will be so eccentric to collide, produce the most stable and almost circular orbits they have today. One hypothesis for this "eccentricity dumping" is that terrestrial creatures formed in gas disks have not yet been released by the Sun. This "gravitational pull" of residual gas will eventually lower the planet's energy, smoothing its orbit. However, the gas, if anything, would prevent the orbit of terrestrial planets from becoming so eccentric in the first place. Another hypothesis is that gravitational pull occurs not between the planets and the residual gas but between the planets and the remaining small bodies. As large bodies move through the crowd of smaller objects, smaller objects, attracted by the gravity of the larger planets, form a region with a higher density, "gravity rise", in the path of larger objects. As they do so, the increased gravity of the wake slows the larger objects into a more orderly orbit.
Asteroid belt
The outer edge of the terrestrial region, between 2 and 4 AU from the Sun, is called the asteroid belt. The asteroid belt initially contains more than enough material to form 2-3 Earth-like planets, and, indeed, a large number of planetesimals are formed there. Like terrestrial, the planets in this region then unite and form the 20-30 planet-sized embryos of the Moon to Mars; However, Jupiter's proximity means that once the planet is formed, 3 million years after the Sun, the region's history changes dramatically. Orbital resonances with Jupiter and Saturn are very strong in the asteroid belt, and gravitational interactions with larger embryos are dispersed much planetesimal to the resonance. Jupiter's gravity increases the velocity of objects in this resonance, causing them to break apart with other objects, instead of taking root.
When Jupiter migrates in after its formation (see Planetary migration below), resonance will sweep asteroid belts, dynamically attracting populations in the region and increasing their velocity relative to each other. The cumulative action of both resonance and embryo is dispersed planetesimally from the asteroid belt or ecstatic of their orbital and eccentric tendencies. Some of these large embryos were also issued by Jupiter, while others may have migrated to the inner Solar System and played a role in the terrestrial terrestrial ending. During this period of primary depletion, the effects of the giant planets and planetary embryos leave the asteroid belt with a total mass equivalent to less than 1% of Earth, which consists mostly of small planetes. It's still 10-20 times more than the current mass in the main belt, which is now about 1/2.000 M ? . A period of secondary depletion that carries the asteroid belt close to the current mass is estimated to have followed when Jupiter and Saturn entered a temporary 2: 1 orbit resonance (see below).
The core impact period of the inner Solar System may play a role on Earth obtaining the current water content (~ 6 ÃÆ' - 10 21 kg) from the asteroid belt early. Fluctuating water has been present in Earth formations and must have been sent from outside, the cooler part of the Solar System. The water may be delivered by planetary embryos and small planetesimals thrown out of the asteroid belt by Jupiter. The population of the major comets discovered in 2006 has also been suspected as a possible source of water for the Earth. In contrast, comets from the Kuiper belt or more distant regions transmit no more than 6% of Earth's water. The panspermia hypothesis states that life itself may have been stored on Earth in this way, although this idea is not widely accepted.
Planet migration
According to the nebular hypothesis, the two outer planets may be in "the wrong place". Uranus and Neptune (known as "ice giants") exist in areas where reduced sun density of nebulae and longer orbital time make their formation so unreasonable. Both are thought to have formed in orbit near Jupiter and Saturn, where more material is available, and have migrated out into their current position for hundreds of millions of years.
Outer planet migration is also needed to explain the existence and properties of the outermost areas of the Solar System. Outside of Neptune, the Solar System continues into Kuiper belts, dispersed disks, and Oort clouds, three small populations of tiny ice bodies considered the origin of the most observed comet. At their distance from the Sun, accretion is too slow to allow the planet to form before the solar nebula is scattered, and thus the initial disk lacks enough mass density to consolidate into the planet. The Kuiper belt is located between 30 and 55 AU from the Sun, while the larger discs are spread over more than 100 AU, and the distant Oort cloud starts at about 50,000 AU. Initially, however, the Kuiper belt is much denser and closer to the Sun, with an outer edge of about 30 AU. The inner edges will be just outside the orbit of Uranus and Neptune, which in turn are much closer to the Sun when they are formed (most likely within the range of 15-20 AU), and in 50% the simulation ends up with opposite locations. , with Uranus farther from the Sun than Neptune.
According to the Nice model, after the formation of the Solar System, the orbit of all the giant planets continues to change slowly, influenced by their interaction with the large number of planetesimal remaining. After 500-600 million years (about 4 billion years ago) Jupiter and Saturn fell into a 2: 1 resonance: Saturn orbits the Sun once for every two orbits of Jupiter. This resonance creates a gravitational impulse to the outer planet, which may cause Neptune to soar past Uranus and plow into the ancient Kuiper belt. The planets disperse most of the small ice bodies inside, as they move out. These planets are then scattered from the next planet they meet in the same way, moving the orbits of the planets as they move inwards. This process continues until the planets interact with Jupiter, whose enormous gravity sends them into highly elliptical orbits or even removes them directly from the Solar System. This causes Jupiter to move slightly inside. The objects scattered by Jupiter into orbit are very elliptical forming the Oort cloud; objects that are scattered to the lower levels by Neptune migrate to form the current Kuiper belt and scattered disks. This scenario describes the low mass of current disk and disk disks. Some of the scattered objects, including Pluto, are gravitically bound to the orbit of Neptune, forcing them into a flat-moving resonance. Finally, the friction in the planetesimal disk makes the orbit of Uranus and Neptune rotate again.
Unlike the outer planets, the inner planets are not expected to migrate significantly above the age of the Solar System, because their orbits remain stable after a period of giant impact.
Another question is why Mars came out so small compared to Earth. A study by Southwest Research Institute, San Antonio, Texas, published June 6, 2011 (called the Grand Tactic hypothesis), proposes that Jupiter has migrated into 1.5 AU. Once Saturn is formed, migrate inward, and form a 2: 3 average motion resonance with Jupiter, this study assumes that both planets migrate back to their present position. Thus Jupiter will consume much material that will create a larger Mars. The same simulation also reproduces the characteristics of a modern asteroid belt, with dried asteroids and water-rich objects similar to comets. However, it is unclear whether conditions in the solar nebula will allow Jupiter and Saturn to return to their current position, and according to current estimates this possibility seems unlikely. In addition, an alternative explanation for a small mass of Mars exists.
Late Heavy Bombardment and after
Gravitational disturbance from outer planet migration will send large amounts of asteroids into the inner Solar System, greatly attenuating the original belt until it reaches a very low mass today. This event may have triggered the Late Heavy Bombardment that occurred about 4 billion years ago, 500-600 million years after the formation of the Solar System. This period of heavy bombing lasted several hundred million years and is evident in the crater still visible on the inner geological bodies of the Solar System such as the Moon and Mercury. The oldest known evidence for life on Earth dates from 3.8 billion years ago - almost immediately after the end of the End Weight Battle.
Impact is considered a regular part of the evolution of the Solar System (if it is rare today). That they continue to happen is evidenced by the collision of Comet Shoemaker-Levy 9 with Jupiter in 1994, the 2009 Jupiter impact event, the Tunguska event, the Chelyabinsk meteor and the Meteor Crater impact feature in Arizona. The process of accretion is, therefore, incomplete, and may still be a threat to life on Earth.
During the evolution of the Solar System, comets were ejected from the inner Solar System by the gravity of the giant planets, and sent thousands of AUs outward to form the Oort cloud, a rounded outer bunch of comet nuclei at the furthest level of the gravitational pull of the Sun. Finally, after about 800 million years, gravitational disturbances caused by galaxy waves, passing stars and giant molecular clouds begin to drain clouds, sending comets to the inner Solar System. The outer evolution of the Solar System also seems to be affected by the weathering of space from the solar wind, the micrometerite, and the neutral components of the interstellar medium.
The evolution of the asteroid belt after the Late Heavy Bombardment is mainly regulated by collision. Objects with large masses have sufficient gravity to withstand material released by hard collisions. In the asteroid belt this is usually not the case. As a result, many larger objects have been fragmented, and sometimes new objects have been forged from the remains in less violent collisions. The moon around some of the current asteroids can only be explained as consolidation of material thrown from the parent object without enough energy to completely release its gravity.
Month
The moon has appeared around most planets and many other bodies of the Solar System. This natural satellite comes from one of three possible mechanisms:
- Co-formation of circular disks (only in the case of giant planets);
- Formation of impact debris (exerts considerable impact on shallow angles); and
- Take a passing object.
Jupiter and Saturn have several big moons, like Io, Europa, Ganymede and Titan, which may come from discs around every giant planet in the same way as planets formed from disks around the Sun. This origin is indicated by the size of the moon and its proximity to the planet. These attributes are not possible through capture, while the nature of the gas from the primary also makes the formation of the collision debris impossible. The giant outer moons tend to be small and have an eccentric orbit with an arbitrary tendency. This is the expected characteristic of the captured body. Most of such moon orbits in the opposite direction of their main rotation. The largest irregular month is the moon of Neptune Triton, which is considered the object of the captured Kuiper belt.
The moons of solid bodies of solar system have been created by both collisions and arrests. Two small moons of Mars, Deimos and Phobos, are considered as captured asteroids. Earth's Moon is thought to have formed as a result of a large collision. Impacted objects may have masses proportional to Mars, and their effects may occur near the end of the giant impact period. The collision kicked into the orbit some of the crashing coat, which then united to the Moon. The impact may be the last in a series of mergers that make up Earth. It has been further hypothesized that Mars-sized objects may have formed at any of the Earth-Sun Lagrangian stable points (either L 4 or L 5 ) and drifted from position. The months of trans-Neptunus Pluto (Charon) and Orcus (Vanth) objects may also have formed through massive collisions: the Pluto-Charon, Orcus-Vanth and Earth-Moon systems are unusual in the Solar System because the mass satellites are at least 1% of the body greater than.
Future
Astronomers predict that the Solar System as we know it today will not change drastically until the Sun has brought together almost all hydrogen fuel in its essence to helium, starting its evolution from the main sequence of the Hertzsprung-Russell diagram and becoming its red giant. stage. Even so, the Solar System will continue to grow until then.
Long-term stability
The Solar System is chaotic over a span of millions and billions of years, with the orbit of open planets for long-term variations. An important example of this disorder is the Neptune-Pluto system, which lies in 3: 2 orbital resonance. Although the resonance itself remains stable, it becomes impossible to predict Pluto's position with any degree of accuracy over 10-20 million years ( Lyapunov time) into the future. Another example is the axis of the Earth's axis, which, due to the friction that arises in the Earth's mantle by tidal interactions with the Moon (see below), can be calculated at a certain point between 1.5 and 4.5 billion years from now.
The planets beyond its orbit are chaotic over a longer span of time, with Lyapunov time in the range of 2-230 million years. In all cases this means that the position of a planet along its orbit eventually becomes impossible to predict with any certainty (so, for example, the winter and summer times become uncertain), but in some cases the orbit itself can change dramatically. Such chaos is very evident as a change in eccentricity, with some orbits of the planet becoming more significant - or less - elliptical.
Ultimately, the Solar System is stable because no planets are likely to collide with each other or be excluded from the system in the next few billion years. Beyond this, in five billion years or more the eccentricity of Mars can grow to about 0.2, as it lies in the Earth-crossing orbit, leading to potential collisions. In the same time scale, the eccentricity of Mercury can grow further, and close encounters with Venus can theoretically extract it from the Solar System altogether or send it on a collision course with Venus or Earth. This can happen in a billion years, according to numerical simulations where Mercury orbit is disrupted.
Ring-month system
The evolution of the moon system is driven by tidal forces. The moon will increase the tidal bulge of the orbiting object (primary) due to the gravitational force of the main diameter in diameter. If a moon revolves in the same direction as the planet's rotation and the planet rotates faster than the orbital moon period, the bulge will continue to be pulled ahead of the moon. In this situation, the angular momentum is transferred from the primary rotation to the satellite revolution. The moon gets energy and gradually turns outward, while the main ones rotate more slowly over time.
Earth and the Moon are one example of this configuration. Today, the Moon is locked tidally on Earth; one of its rounds around Earth (currently about 29 days) equals one of its rounds about its axis, thus always showing one face to Earth. The moon will continue to recede from Earth, and the Earth's spin will continue to slow down gradually. Approximately 50 billion years, if they survive from the expansion of the Sun, Earth and Moon will become locked tidically to each other; each will be trapped in so-called "spin orbit resonance" where the Moon will circle the Earth in about 47 days and both the Moon and Earth will revolve around their axis at the same time, each seen only from one hemisphere to the other. Another example is the Galilean moons in Jupiter (also many smaller Jupiter moons) and most of the larger moons of Saturn.
Different scenarios occur when the moon revolves around the primer faster than the main turn, or rotates in the opposite direction of the planet's rotation. In this case, the tidal bulge lags behind the moon in its orbit. In the first case, the angular momentum displacement direction is reversed, so the primary velocity rotation rises while the satellite orbit shrinks. In the latter case, the angular momentum of rotation and revolution has the opposite sign, so the transfer leads to a decrease in the magnitude of each (which cancel each other). In both cases, tidal deceleration causes the moon to rotate in the primary direction until it is torn by tidal pressure, potentially creating a planetary ring system, or crashing into the planet's surface or atmosphere. Such fate awaits the Phobos Mars months (within 30 to 50 million years), Triton Neptune (3.6 billion years), Metis and Adrastea Jupiter, and at least 16 small satellites of Uranus and Neptune. Desdemona Uranus might even collide with one of her neighboring moon.
The third possibility is where the primers and moon are locked tidid to each other. In this case, the tidal bulge remains below the moon, there is no angular momentum transfer, and the orbital period will not change. Pluto and Charon are examples of this type of configuration.
Prior to the 2004 arrival of the Cassini-Huygens spacecraft, Saturn's rings are widely considered much younger than the Solar System and are not expected to last more than 300 million years. The gravitational interaction with Saturn's moon is expected to gradually sweep the outer edges of the rings to the planet, with abrasion by meteorites and gravity of Saturn finally taking the rest, leaving Saturn unadorned. However, data from the Cassini mission prompted scientists to revise the preliminary view. The observations revealed cold clumps of 10 km that repeatedly broke and changed, keeping the ring fresh. Saturn's rings are much more massive than any other giant planet's rings. This massive mass is thought to have retained the Saturn ring since it first formed 4.5 billion years ago, and is likely to preserve it for billions of years to come.
The sun and planetary environment
In the long run, the greatest changes in the Solar System will come from the changes of the Sun itself as we age. When the sun burns through the supply of hydrogen fuel, it gets hotter and burns the remaining fuel faster. As a result, the Sun grows brighter at a rate of ten percent every 1.1 billion years. Within a billion years, as the output of solar radiation increases, the habitat's habitable zone will move out, making the Earth's surface too hot for liquid water to exist there naturally. At this point, all life on land will be extinct. The evaporation of water, a powerful greenhouse gas, from the surface of the oceans could accelerate rising temperatures, potentially ending all life on Earth even faster. During this time, it is possible that Martian surface temperatures are gradually increasing, carbon dioxide and water are now frozen beneath the surface regolit will release to the atmosphere, creating a greenhouse effect that will heat the planet until it reaches conditions parallel to the Earth today, ahead of life potential. With 3.5 billion years from now, Earth's surface conditions will be the same as Venus today.
About 5.4 billion years from now, the core of the Sun will become hot enough to trigger hydrogen fusion in the surrounding skin. This will cause the outer layer of the star to widen, and the star will enter a phase of life where it is called a red giant. In 7.5 billion years, the Sun will expand to a radius of 1.2 AU - 256 times the current size. At the end of the red giant branch, as a result of a very rising surface area, the surface of the Sun will be much colder (about 2600 ° C) than it is now and its luminosity is much higher - up to 2,700 solar luminosity today. For part of its red-giant life, the Sun will have strong stellar winds that will carry about 33% of its mass. During these times, it is possible that the moon of Saturn Titan can reach the surface temperatures necessary to support life.
As the Sun expands, it will swallow the planet Mercury and Venus. The fate of the earth is less clear; although the Sun will envelop Earth's current orbit, losing the star's mass (and thus weaker gravity) will cause the orbits of the planets to move farther. If only for this, Venus and Earth might escape incineration, but a 2008 study showed that Earth would likely be swallowed as a result of tidal interactions with outside envelopes tied to the Sun.
Gradually, burning hydrogen in the shell around the sun's core will increase the core mass until it reaches about 45% of the current solar mass. At this point, the density and temperature will become so high that the fusion of helium into carbon will begin, leading to helium flash; The sun will shrink from about 250 to 11 times its fingers (sequences). As a result, its luminosity will decrease from about 3,000 to 54 times the current level, and its surface temperature will rise to about 4770 K. The sun will be a horizontal giant, burning helium in essence as stable as burning hydrogen today. The helium melting phase will only last for 100 million years. Eventually, he had to re-use the reserves of hydrogen and helium in the outer layers and would expand the second time, turning into what is known as an asymptotic giant. Here the luminosity of the Sun will increase again, reaching about 2,090 luminosity today, and will cool down to about 3500 ° C. This phase lasts about 30 million years, after which, over 100,000 years, the Sun's remaining outside its layers will fall out, spewing enormous amounts of matter into space and forming a circle that is known (misleading) as a planetary nebula. The ejected material will contain helium and carbon produced by the Sun's nuclear reaction, continuing the enrichment of interstellar medium with heavy elements for future generations of stars.
This is a relatively peaceful event, nothing resembling a supernova, which the Sun is too small to live as part of its evolution. Every observer present to witness this event will see a massive increase in the speed of the solar wind, but not enough to completely destroy the planet. However, the loss of star mass can send the orbits of the planet that survived into chaos, causing some to collide, others will be excluded from the Solar System, and others will be torn apart by tidal interactions. After that, all that is left of the Sun is a white dwarf, an incredibly dense object, 54% of its original mass but only the size of the Earth. Initially, this white dwarf may be 100 times brighter like the Sun now. It will be composed entirely of degenerated carbon and oxygen, but will never reach a temperature sufficiently hot to combine these elements. Thus, the white dwarf Sun will gradually cool down, grow dim and dim.
When the Sun dies, its gravitational pull toward orbiting bodies such as planets, comets and asteroids will weaken due to loss of mass. All remaining planetary orbits will expand; if Venus, Earth and Mars still exist, its orbit will be around 1.4Ã, AU (210,000,000 km), 1.9 AU (280,000,000 km), and 2.8 AU (420,000,000 km). They and the rest of the planet will be dark, cold, completely devoid of any form of life. They will continue to orbit their star, their speed slows down as their distance rises from the Sun and the sun's reduced gravity. Two billion years later, when the sun has cooled to the range of 6000-8000K, the carbon and oxygen at the core of the Sun will freeze, with more than 90% of the rest mass assuming crystal structure. Finally, after billions more years, the Sun will eventually stop shining, becoming a black dwarf.
Galaxy interaction
The Solar System runs itself through the Milky Way in a circular orbit about 30,000 light-years from the Galactic Center. Its speed is about 220 km/sec. The period required for the Solar System to complete a revolution around the Galactic Center, the year of the galaxy, is in the range of 220-250 million years. Since its formation, the Solar System has completed at least 20 such revolutions.
Scientists speculate that the path of the Solar System through galaxies is a factor in the periodicity of mass extinctions observed in Earth's fossil record. One hypothesis presupposes that the vertical oscillations made by the Sun as it orbits the Galactic Center cause it to regularly pass through the galactic plane. When the orbit of the Sun takes it outside the galaxy disk, the influence of galaxy waves is weaker; when re-enters the galactic disk, as it happens every 20-25 million years, it comes under the influence of a much stronger "ocean wave" which, according to the mathematical model, increases the comet cloud flux of Oort into the Sun System by a factor of 4, to a major increase in the likelihood of a devastating impact.
However, others argue that the Sun is currently close to the galactic plane, but the last major extinction event was 15 million years ago. Therefore, the vertical position of the Sun can not alone explain such periodic extinctions, and that extinction actually occurs when the Sun passes the galactic spiral arms. The spiral arm is a house not only for the larger number of clouds of molecules, whose gravity can distort the Oort cloud, but also to higher concentrations of the bright blue giant, which live for a relatively short period and then explode violently as a supernova.
Galaxy collision and planetary disturbance
Although most of the galaxies in the universe move away from the Milky Way, the Andromeda Galaxy, the largest member of the Local Galaxies Group, is heading towards it at about 120 km/sec. In 4 billion years, Andromeda and Milky Way will collide, causing both to change shape as tidal forces distort their outer arm into a very large tidal tail. If this initial disturbance occurs, astronomers calculate a 12% chance that the Solar System will be pulled out to the tail of the Milky Way and a 3% chance that it will become gravitationalally bound to Andromeda and thus part of the galaxy. After a series of further blows, where the possibility of Solar System expenditure increased by 30%, supermassive supermassive black holes will merge. Finally, in about 6 billion years, the Milky Way and Andromeda will complete their merger into a giant elliptical galaxy. During the merger, if there is enough gas, an increase in gravity will force the gas into the center of the elliptical galaxy that it forms. This can lead to a brief period of intensive star formation called Starburst. In addition, gas infalling will feed the newly formed black hole, turning it into an active galactic nucleus. This interaction strength will likely push the Solar System into the outer circle of the new galaxy, leaving it relatively unscathed by radiation from this collision.
It is a common misconception that this collision will disrupt the orbits of planets in the Solar System. While it is true that the gravity of a passing star can release the planet into the interstellar space, the interstellar distance is so great that the possibility of a Milky Way-Andromeda collision causing disruption to the individual star system is negligible. Although the Solar System as a whole can be affected by these events, the Sun and the planets are not expected to be disturbed.
However, over time, the cumulative probability of the possibility of meeting the rising stars, and the disturbance of the planets becomes inevitable. Assuming that the Big Crunch or Big Rip scenario for the end of the Universe does not occur, the calculations show that the gravity of the passing star will have completely eliminated the dead Sun from the remaining planets in 1st, quadrillion (10 15 ) year. This point marks the end of the Solar System. Although the Sun and the planets can survive, the Solar System, in a meaningful sense, will cease to exist.
Chronology
The time frame of the formation of the Solar System has been determined using radiometric dating. Scientists estimate that the Solar System is 4.6 billion years old. The oldest known mineral grain on Earth is about 4.4 billion years. These old rocks are scarce, because the Earth's surface is constantly reshaped by erosion, volcanism, and tectonic plates. To estimate the age of the Solar System, scientists used meteorites, which formed during the initial condensation of the solar nebula. Almost all meteorites (see Canyon Diablo meteorite) are found to have an age of 4.6 billion years, which suggests that the Solar System should be at least as old as this.
The study of discs around other stars has also done much to form a time frame for the formation of the Solar System. Stars between one and three million years have gas-rich disks, while discs around stars older than 10 million years have little or no gas, suggesting that the giant planet inside has stopped forming.
Solar System evolution timeline
Note: All dates and times in this timeline are approximate and should be considered as a sequence of major indicators only.
See also
Note
References
Bibliography
- Duncan, Martin J.; Lissauer, Jack J. (1997). "Orbital Stability of Uranian Satellite Systems". Icarus . 125 (1): 1-12. Bibcode: 1997Icar..125.... 1D. doi: 10.1006/icar.1996.5568.
- Zeilik, Michael A.; Gregory, Stephen A. (1998). Introduction Astronomy & amp; Astrophysics (4th ed.). Saunders College Publishing. ISBN: 0-03-006228-4.
External links
- The 7M animation of skyandtelescope.com shows the earliest evolution of the outermost Solar System.
- QuickTime animations from collisions between the Milky Way and Andromeda
- How the Sun Will Die: And What Happened to Earth (Video on Space.com)
Source of the article : Wikipedia
0 Comments