The structure of the solar system can be roughly divided into five parts. Summary of structural distance of solar system (from the sun)

(AU) Remarks on Stellar Planets and Asteroid Comets 0 G2V Yellow Main Sequence Stars: Perihelion of Sun-Sun-Grazing Comet 0~2 Solar Wind Layer: Solar Popular Interstellar Material Solar Wind Layer Current Page Terrestrial Planets: Mercury, Venus, Earth and Mars Near-Earth Asteroids: Ardennes Group, Apollo Group, Amorkon 2~3.2 Ceres Asteroids with Main Belt Comets 3.2~30 Woody Planets: Jupiter. Neptune Troyi group Centaur Jupiter family Harley-type Khyron star 30~50 Pluto, pregnant star, short-period comet in the Kuiper belt of bird god come from 50~75, and long-period comet comes from the scattering disk of the ecliptic. It comes from aperiodic comets: parabolic comet hyperbolic comet 75~ 1 10, terminal shock wave, solar sheath solar wind layer top-solar magnetic field boundary 1 10~230, bow shock wave -230 ~ 65430. 000 interstellar matter-inside Oort Cloud: Sedna10000 ~100000-Oort Cloud Solar Gravitational Boundary 100000~ Nearest star: Alpha Centauri, an exoplanet in proxima centauri-solar system. It has enough mass (about 330,000 times that of the earth), so that the internal pressure and density are enough to suppress and bear the huge energy generated by nuclear fusion, and let the energy enter space stably in the form of radiation, such as visible light.

The sun is classified as a medium-sized yellow dwarf, but such a name is easily misunderstood. In fact, in our galaxy, the sun is quite big and bright. According to the corresponding relationship between surface temperature and brightness of Hertzog diagram, the stars are classified. Usually, stars with high temperature will be brighter, and stars following this rule will be located in the so-called main sequence zone, with the sun at the center of this zone. However, not many stars are bigger and brighter than the sun, while many stars are darker and colder.

The sun is in the heyday of star evolution, and the core nuclear fusion hydrogen has not been used up. The brightness of the sun will still increase day by day, and the early brightness is only 75% of the contemporary brightness. By calculating the proportion of hydrogen and helium in the sun, it is considered that the sun has completed half of its life cycle, and will run out of hydrogen needed for nuclear fusion in about 5 billion years. The sun will leave the main sequence star stage and become a bigger and brighter red giant with a lower surface temperature and brightness thousands of times that of the middle-aged sun. The sun is the first group of stars born in the late evolution of the universe. It has more metals heavier than hydrogen and helium than the stars in the second group (this is an astronomical saying: all atoms with more atoms than helium are metals. )。 Elements heavier than hydrogen and helium are formed in the core of a star and must be released into space by supernova explosion. In other words, these heavy elements only exist in the universe after the death of the first generation of stars. The oldest stars have only a small amount of metal, and later stars have more metal. High metal content is considered to be the key to the development of planetary systems by solar energy, because planets are formed by the accumulation of metal substances. In addition to light, the sun constantly sends out a stream of electrons (plasma), which is called the solar wind. The speed of this particle flow is 6.5438+0.5 million kilometers per hour, forming a thin atmosphere (solar circle) in the solar system, with a range of at least 654.38+0.000 astronomical units (heliopause), which is what we call interplanetary matter. The sunspot period of the sun (1 1 year) and the interference caused by frequent flash flames and coronal mass ejections in the solar circle have produced space climate. The solar current sheet produced by the magnetic field rotating with the rotation of the sun in interplanetary matter is the largest structure in the solar system.

The earth's magnetic field protects the earth's atmosphere from the solar wind. Mercury and Venus have no magnetic fields, and the solar wind gradually draws their atmospheres into space. Near the magnetic poles near the earth, such as the South Pole and the North Pole, you can see the aurora produced by the interaction between the solar wind and the earth's magnetic field.

Cosmic rays come from outside the solar system, and the solar circle shields the solar system. The planet's magnetic field also provides some protection for the planet itself. The density of cosmic rays in interstellar matter is related to the intensity change of solar magnetic field cycle, so how much cosmic rays change in the solar system is still unknown.

Interplanetary matter gathers into cosmic dust in at least two disk-shaped regions. The first area is the ecliptic dust cloud, which is located in the inner solar system and is the cause of zodiacal light. They may be caused by the collision between celestial bodies and planets in the asteroid belt. The second region extends in the range of 10 ~ 40 astronomical units, which may be caused by a similar collision between celestial bodies in the Kuiper Belt. Traditionally, the inner solar system is the name of the region of terrestrial planets and asteroid belts, which is mainly composed of silicates and metals. This area is squeezed very close to the sun, and the radius is shorter than the distance between Jupiter and Saturn.

Inner planets The four inner planets or terrestrial planets are characterized by high density, composed of rocks, few or no satellites, and no ring system. They are composed of high melting point minerals such as silicate minerals, the crust is solid surface and semi-liquid mantle, and the metal core is composed of iron and nickel. Three of the four stars (Venus, Earth and Mars) have rich atmospheres, and they all have the surface features of impact craters and geological structures (graben and volcano, etc.). ) The inner planets are easily confused with the inner planets (Mercury and Venus) which are closer to the sun than the Earth. Planets run on a plane and face in one direction. Mercury (? ) (0.4 astronomical unit) is the closest planet to the sun and the smallest planet (0.055 earth mass). It has no natural satellites, and the only known geological features are folded ridges that may have been produced during early history and contraction, except for impact craters. Mercury, including gas atoms bombarded by the solar wind, has only a negligible atmosphere. As of 20 13, the relatively huge iron core and thin mantle cannot be explained. The hypothesis includes that a huge impact peeled off its shell, and the solar energy at a young age inhibited the growth of the shell.

Venus (♀) (0.7 astronomical unit) is similar in size to the Earth (0.86 earth mass), and also has a thick silicate mantle surrounding the core like the Earth, which has strong evidence of atmospheric and internal geological activities. However, its atmospheric density is 90 times higher than that of the earth, it is very dry, and there are no natural satellites. It is a hot planet with a surface temperature of over 400℃, which is probably caused by a large amount of greenhouse gases in the atmosphere. There is no clear evidence that Venus' geological activities are still going on, but the atmosphere without magnetic field protection should be exhausted, so it is considered that Venus' atmosphere is supplemented by volcanic eruption.

Earth (⊕) (1 astronomical unit) is the largest and densest planet among the inner planets, and it is also the only planet with continuous geological activities and life (so far scientists have not explored other creatures from space). Among terrestrial planets, it also has a unique hydrosphere and observed plate structure. The earth's atmosphere is completely different from other planets, and it has been transformed into free oxygen containing 2 1% by the creatures here. It has only one satellite, the moon; The moon is also the only big satellite among terrestrial planets. It takes about 365 days for the earth (sun) to make a revolution, and it takes about 1 day for the earth to make a revolution. The sun doesn't always point directly at the equator, because the earth tilts slightly when it rotates around the sun. )

Mars (♂) (1.5 astronomical unit) is smaller than Earth and Venus (0. 17 Earth mass), and only has a thin atmosphere dominated by carbon dioxide. Its surface, such as Mount Olympus, has dense and huge volcanoes, and Mariner Canyon has deep graben, indicating that there was still strong geological activity not long ago. Mars has two natural small satellites, demos and faubus, which may be captured asteroids. Asteroids are the most important members of small celestial bodies in the solar system, mainly composed of rocks and nonvolatile matter.

The main asteroid belt lies between the orbits of Mars and Jupiter, 2.3 to 3.3 astronomical units away from the sun. They are considered to be residual materials disturbed by Jupiter's gravity during the formation of the solar system.

Asteroids range in size from hundreds of kilometers to microns. All asteroids except Ceres, the largest, are classified as small objects in the solar system, but several asteroids such as Vesta and blade master may be reclassified as dwarf planets if they can be confirmed to be in hydrostatic equilibrium.

There are tens of thousands, possibly millions of small celestial bodies with a diameter of more than one kilometer in the asteroid belt. Nevertheless, the total mass of the asteroid belt is still impossible to reach one thousandth of the mass of the earth. The members of the asteroid main belt are still sparse, so so far no spacecraft has had an accident when crossing.

Small celestial bodies with a diameter of 10 to10.4m are called meteoroids.

Ceres (2.77 astronomical units) is the largest celestial body in the main belt and the only dwarf planet in the main belt. Its diameter is close to 1000 km, so its own gravity is enough to make it a sphere. It was considered a planet when it was discovered in the early19th century, and was reclassified as an asteroid in the1850s because more small objects were discovered. In 2006, it was reclassified as a dwarf planet again. Asteroids in the main belt can be divided into several asteroid groups and asteroid families according to orbital elements. Asteroid satellites are small celestial bodies orbiting larger asteroids, and their identification is not as clear as that of satellites orbiting planets, because some satellites are almost as big as their mother bodies.

There are also comets in the main belt, which may be the main source of water on the earth.

The position of the Trouvat asteroid is at the L4 or L5 point of Jupiter (the unstable gravitational equilibrium point before and after the planetary orbit), but the name "Trouvat" is also used for the small celestial bodies located at the Lagrangian point in the orbits of other planets or satellites. The Hilda family is an asteroid family, and its orbital period oscillates with Jupiter's 2: 3 * *. When Jupiter orbits the sun twice, this group of asteroids will orbit the sun three times.

The inner solar system also contains many "naughty" asteroids and dust particles, many of which will cross the orbit of the inner planet. The four outer planets, also known as wooden planets, contain 99% of the known mass around the sun. The atmospheres of Jupiter and Saturn are rich in hydrogen and helium, while those of Uranus and Neptune are rich in "ice", such as water, ammonia and methane. Some astronomers think they should be classified into another category, called "Uranus family" or "ice giant". All four gas giants have planetary rings, but only Saturn's rings can be easily observed from the earth. The name "exoplanet" is easily confused with "exoplanet". In fact, it refers to planets outside the earth's orbit, in addition to Mars.

Jupiter (? ) (5.2 astronomical units), mainly composed of hydrogen and helium, its mass is 3 18 times that of the earth and 2.5 times that of other planets combined. Jupiter's abundant internal heat leads to some almost permanent features in its atmosphere, such as cloud bands and great red spots. There are 63 satellites discovered by Jupiter, and the largest four, Ganymede, Calisto, Eo and Europa, show similar characteristics to terrestrial planets, such as volcanism and internal heat. Ganymede is bigger than Mercury and the largest satellite in the solar system.

Saturn (no? , but? ) (9.5 astronomical units), famous for its obvious ring system, is very similar to Jupiter, such as the structure of the atmosphere. Saturn is not very big, its mass is only 95 times that of the earth. It has 60 known satellites, Titan and Enceladus, and huge ice and volcanoes, showing signs of geological activity. Titan is bigger than mercury and is the only satellite in the solar system that really has an atmosphere.

Uranus (? , there are several symbols, this is one of them) (19.2 astronomical unit), is the lightest exoplanet, and its mass is 14 times that of the earth. Its axis of rotation is inclined at 90 degrees to the ecliptic, so it lies horizontally around the sun, which is very unique among the planets. Among gas giants, its core temperature is the lowest, and it only radiates very little heat into space. Uranus has 27 known satellites, the largest of which are Titan, oberon, Ambarel, Ariel and Miranda.

Neptune (? Although (30 astronomical units) looks smaller than Uranus, its higher density still makes its mass 17 times that of the earth. Although it radiates more heat, it is far less than Jupiter and Saturn. Neptune is known to have 13 satellites, and the largest triton is still active in geological activities. Geysers erupt liquid nitrogen, and it is also the only retrograde satellite in the solar system. In the orbit of Neptune, there are some asteroids with the orbit of 1: 1, which form the Trojan Group of Neptune. Comets are small celestial bodies in the solar system, usually only a few kilometers in diameter, and are mainly composed of volatile ice. Their orbits have high eccentricity, perihelion is generally inside the orbit of the inner planet, while apohelion is outside Pluto. When a comet enters the inner solar system, its proximity to the sun will lead to the sublimation and ionization of substances on its ice surface, resulting in coma and dragging out a tail composed of gas and dust particles visible to the naked eye.

Short-period comets are comets with orbital periods shorter than 200 years, and long-period comets have orbital periods as long as thousands of years. Short-period comets, such as Halley's Comet, are thought to come from the Kuiper Belt; Long-period comets, such as Comet Hale Popper, are thought to have originated from Oort Cloud. There are many comets, such as Cruz family comets, which may have originated from a collapsed matrix. Some comets with hyperbolic orbits may come from outside the solar system, but it is difficult to accurately measure these orbits. Comets whose volatile substances are dispersed by solar heat are usually classified as asteroids.

Centaurs are scattered in the range of 9 to 30 astronomical units, that is, they orbit Jupiter and Neptune and are ice-based objects similar to comets. The largest celestial body known to centaurs is 10 199 Chariklo, with a diameter of 200 to 250 kilometers. The first one was discovered in Long Xing in 2060. It was classified as a comet because it would produce a comet-like coma when it approached the sun. Some astronomers classify Centaur as a discrete celestial body inside the Kuiper Belt and regard it as a continuation of the external discrete disk. The area outside Neptune, usually called the outer solar system or the outer Neptune area, is still a vast unexplored space. This area seems to be the world of small celestial bodies in the solar system (the largest diameter is less than one-fifth of that of the earth and the mass is much smaller than that of the moon), which is mainly composed of rocks and ice.

The original form of the Kuiper Belt is considered to be an annular belt composed of debris and debris similar in size to asteroids, but mainly composed of ice, which spreads at a distance of 30 to 500 astronomical units from the sun. This area is considered to be the source of short-period comets, such as Halley's Comet. It is mainly composed of small celestial bodies in the solar system, but many of the largest celestial bodies in the Kuiper Belt, such as Chuangshenxing, Varuna, 2003 EL6 1, 2005 FY9 and Elkus, may be classified as dwarf planets. It is estimated that there are more than 100000 celestial bodies with a diameter of more than 50 kilometers in the Kuiper Belt, but the total mass may be only one tenth or even one percent of the mass of the earth. Many celestial bodies in the Kuiper Belt have more than two satellites, and most of their orbits are not on the ecliptic plane.

Kuiper belt can be roughly divided into * * vibration belt and traditional belt. * * The vibration band consists of celestial bodies that have a * * vibration relationship with Neptune's orbit (Neptune orbits the sun three times and twice, or Neptune orbits the sun twice and only once). In fact, Neptune itself is a member of the * * * vibration belt. Traditional members are celestial bodies that do not vibrate with Neptune and are scattered in the range of 39.4 to 47.7 astronomical units. The traditional Kuiper Belt celestial bodies are classified as QB 1 celestial bodies with the name 1992 QB 1, which is one of the first three celestial bodies discovered.

Pluto (? At present, Ka Rong is not sure whether Ka Rong should be classified as a satellite or a dwarf planet, because the orbital centers of mass of Pluto and Ka Rong are not below the surface of either one, forming a Pluto-Ka Rong binary system. Two other small satellites, the Knicks and Xu Dela, revolve around Pluto and Ka Rong.

Pluto vibrates 3:2 * * with Neptune on the * * * vibration band (Pluto orbits the sun twice and Neptune orbits the sun three times). The objects with such orbits in the Kuiper Belt are collectively called ghost-like objects.

The discrete disks overlap with the Kuiper Belt, but extend outward to further space. The celestial bodies in the discrete disk should be in the early process of the formation of the solar system, because the gravitational disturbance caused by Neptune's outward migration was thrown into the fluctuating orbit from the Kuiper Belt. The perihelion of most ecliptic discrete celestial bodies is in the Kuiper Belt, but the apohelion can be as far as 150 astronomical unit. The inclination angle of the track to the ecliptic plane is also very large, and some of them are even perpendicular to the ecliptic plane. Some astronomers think that the ecliptic discrete celestial bodies should be another part of the Kuiper Belt and should be called the Kuiper Belt discrete celestial bodies.

Venus (136 199 Eris) (with an average distance of 68 astronomical units), also known as Zener, is the largest known discrete celestial body of the ecliptic. This dwarf planet is 65.438+04 billion kilometers away from the sun. In addition, it has a satellite. This led to the debate about planets. At the time of discovery, some people claimed to be the tenth largest planet in the solar system, but later Pluto was defeated and became a dwarf planet. After a heated debate, astronomers finally voted to reduce the number of planets in the solar system to eight and classify Pluto as a "dwarf planet", including Eris and the asteroid Ceres.

In 2003, scientists from California Institute of Technology discovered this planet at the edge of the solar system, numbered 2003UB3 13, and temporarily named it Zena. It was not until July 29th, 2005 that this discovery was made public. It is reported that on August 24th, 2006, at the General Assembly of the International Astronomical Union, astronomers from all countries denied that it was a big planet.

According to reports, Zena's radius is about 1490 miles, which is 77 miles larger than Pluto, a dwarf planet on the edge of the solar system. Zena is 9 billion miles away from the sun, about three times the distance from Pluto to the sun, or about 97.6 astronomical units. An astronomical unit refers to the distance between the sun and the earth. Gina needs 560 years to go around the sun.

This star is round and may be twice as big as Pluto. He estimated that the newly discovered star has an estimated diameter of 2 100 miles, which is 1.5 times that of Pluto.

This star keeps a 45-degree angle with the main plane of the solar system, and most other planets move in the solar system. That's why it hasn't been discovered yet, Brown said.

2016 65438+1On October 20th, American scientists announced the discovery of an unknown giant planet nicknamed "the ninth planet" in the sun. KonstantinBatygin and MikeBrown, researchers in the Journal of Astronomy, said that they discovered the planet through mathematical models and computer simulations, although they did not directly observe it. The mass of this star is about 10 times that of the earth, and the average distance from its orbit to the sun is 20 times that of Neptune. It takes 65,438+00,000 to 20,000 years for this new planet to orbit the sun once. The mass of this planet is about 5000 times that of Pluto. Scientists believe that this planet is gaseous, similar to Uranus and Neptune, and will be the real ninth planet. The solar circle can be divided into two regions, and the maximum distance of solar wind transmission is about 95 astronomical units, which is three times the orbit of Pluto. This is the edge of the terminal shock wave, which is where the solar wind and the interstellar medium collide and impulse each other. The solar wind slows down, condenses and becomes more chaotic here, forming a huge elliptical structure, the so-called solar sheath, which looks and behaves like the tail of a comet and continues to extend outward about 40 astronomical units along the direction of the stellar wind, but the tail in the opposite direction extends several times this distance. The outer edge of the solar circle is the heliopause, where the solar wind finally ends and the interstellar space is outside.

The shape and form of the outer edge of the solar circle are likely to be influenced by the hydrodynamic interaction with interstellar matter and the solar magnetic field prevailing at the southern end. For example, its shape is enlarged by 9 astronomical units (about 65.438+0.5 billion kilometers) in the northern hemisphere than in the southern hemisphere. Outside the heliosphere, there is an arcuate shock wave of about 230 astronomical units, which is generated when the sun passes through the Milky Way.

No spacecraft flew over the top of the heliosphere, so the environmental conditions of interstellar space could not be determined. We know little about how the solar circle protects the solar system under cosmic rays. To this end, people have begun to put forward the task of flying over the solar circle. Is a hypothetical spherical cloud around the solar system, full of many inactive comets, about 50,000 to 65,438+000,000 astronomical units away from the sun, almost equal to a light year, that is, a quarter of the distance between the sun and proxima centauri.

Theoretically, Oort Cloud has trillions of icy objects and huge mass, and surrounds the solar system with a distance of about 5,000 astronomical units, up to 10000 astronomical units, which is considered as the source of long-period comets. People think they are comets thrown there from the inner solar system by the gravity of outer planets. Objects in the Oort cloud move very slowly and are affected by some unusual circumstances, such as collisions, or gravity passing through celestial bodies, or galactic tides.

Sedna and Nolte Cloud

Sedna is a huge red ghostly celestial body with perihelion of 76 astronomical units and apohelion of 928 astronomical units. It takes 65,438+0 to complete a huge orbit with high ellipticity in 2050. Michael brown discovered this celestial body in 2003, because its perihelion is too far away to be affected by Neptune's migration, so he thinks it is not a member of the discrete disk or the Kuiper Belt. He and other astronomers think it belongs to a new classification. Also belonging to this new group are perihelion of 45 astronomical units, apohelion of 4 15 astronomical units, orbital period of 2000 CR 105 of 3420, perihelion of 2 1 astronomical units, apohelion of 1000 astronomical units and orbital period of 60. Brown named this ethnic group Naioyun. Although it is far from the sun, it is still very close, which may be formed through a similar process. Sedna's shape has been confirmed, very much like a dwarf planet. Five dwarf planets have been identified: Ceres, Pluto, Eris, Makemake and Haumea.