Universe
They are all celestial bodies, and comets are composed of various frozen impurities and dust. Astronomers figuratively call it a "dirty snowball." When it runs near the sun, under the action of sunlight and heat, the dirty snow and solidified gas and ice in the outer layer of the "dirty snowball" quickly evaporate, gasify, expand, and erupt. At this time, the comet's The volume expanded dramatically and was clearly divided into two parts: the comet's head and its tail. The brightest part in the center of the comet head is the comet nucleus, which is the body of the "dirty snowball"; the material ejected from the surface of the comet nucleus is vaporized and wrapped around the comet nucleus, forming a coma. The coma is also surrounded by a thin layer of hydrogen cloud, called a coma. The tail trailing behind the comet's head is the comet's tail, which is formed when gas, dust and other materials in the comet's head are pushed out by the sun's powerful radiation pressure and solar wind. Therefore, the comet's tail always faces away from the sun. The closer it is to the sun, the longer the comet's tail.
Asteroids are celestial bodies that orbit the sun but are too small to be called planets. Asteroids can range from as large as Ceres, which is about 1,000 kilometers in diameter, to as small as a pebble. There are 16 asteroids with a diameter of more than 240 kilometers. They are located in space from the orbit of the Earth to beyond the orbit of Saturn. Most asteroids are concentrated in the asteroid belt between the orbits of Mars and Jupiter. Some asteroids have orbits that intersect with Earth's orbit, and some have collided with Earth.
Asteroids are the remaining material after the formation of the solar system. One theory is that they are the remnants of a planet that was destroyed in a giant collision long ago. However, these asteroids are more likely to be materials that never formed a single planet. In fact, if all the asteroids were added together to form a single celestial body, it would be less than 1,500 kilometers in diameter - smaller than the radius of the moon.
Since asteroids are materials from the early solar system, scientists are very interested in their composition. When the space probe passed through the asteroid belt, it was discovered that the asteroid belt was actually very empty, and the asteroids were very far apart. Before 1991, asteroid data were obtained only through ground-based observations. In October 1991, the Galileo spacecraft visited the asteroid 951 Gaspra and obtained the first high-resolution photos of an asteroid. In August 1993, Galileo flew by the asteroid 243 Ida, making it the second asteroid visited by a spacecraft. The Gaspra and Ida asteroids are both metal-rich and belong to S-type asteroids.
Much of what we know about asteroids comes from analyzing the space debris that falls to the Earth's surface. Asteroids that collide with Earth are called meteoroids. When a meteoroid breaks into our atmosphere at high speed, its surface vaporizes due to high temperature due to friction with the air, and emits a strong light. This is a meteor. If a meteoroid falls to the ground without burning up completely, it is called a meteorite. Jian? After analysis of all meteorites, 92.8% of them are silica (rock), 5.7% are iron and nickel, and the remaining part is a mixture of these three substances. Meteorites with a large stone content are called meteorites, and meteorites with a large iron content are called meteorites. Because meteorites are so similar to Earth rocks, they are difficult to identify.
On June 27, 1997, the NEAR probe passed by the asteroid 253 Mathilde. This opportunity allows scientists to observe this carbon-rich C-type asteroid up close for the first time. This visit was the only one since the NEAR detector was not specifically used to investigate it. NEAR was used to conduct a survey of the asteroid Eros in January 1999.
Astronomers have made ground observations of many asteroids. Some well-known asteroids include Toutais, Castalia, Vesta and Geographos. For the asteroids Toutatis, Castalia and Geographos, astronomers studied them through radio observations from the ground as they approached the sun. The Vesta asteroid was discovered by the Hubble Space Telescope.
The discovery of asteroids is closely related to the proposal of the Titius-Bode rule. According to this rule, there should be a planet at a distance of 2.8 astronomical units from the sun. Pia on New Year's Day in 1801 Sure enough, the first asteroid Ceres was discovered there. In the following years, Pallas, Juno, and Vesta, which were in similar orbits to Ceres, were discovered one after another. The introduction of astrophotography and the use of scintillation comparators greatly increased the annual discovery rate of asteroids. By 1940, there were 1,564 asteroids with permanent numbers. Among them, the German astronomers Enke and Hansen made particularly great contributions because of their expertise in orbital calculations, and Wolff and Reinmutt made many observations.
The naming rights of asteroids belong to the discoverers. In the early days, I liked to use the name of the goddess, but later I used the acronym of the name of a person, a place, a flower, or even an organization. Some asteroid groups and asteroids are particularly famous, such as the Trojan Group, the Apollo Group, Icarus, Eros, Hidalgo, etc. According to statistical analysis based on the number of orbital roots, the number of asteroids with an orbital inclination angle of about 5 degrees and an eccentricity of about 0.17 is the largest. The Kirkwood Gap is the most famous distribution feature calculated based on the average heliocentric distance of asteroids. There is a statistical relationship between the asteroid number N and the average opposition magnitude m, logN=0.39m-3.3. The asteroid diameter d and the absolute magnitude g satisfy the statistical formula logd(km)=3.7-0.2g. The distribution of the number of asteroids with diameter shows a discontinuity near a diameter of about 30 kilometers.
There are many satellites, here we only introduce Io 1, which was discovered by Galileo and Marius in 1610.
Unlike the moons of the outer solar system, Io and Europa are similar in composition to the terrestrial planets and are mainly composed of hot silicate rocks. Recent data sent back from the Galileo spacecraft indicate that Io has an iron core (possibly mixed with iron-containing sulfides) with a radius of at least 900 kilometers.
The surface of Io is unique from other bodies in the solar system, which surprised Voyager scientists when they first made contact. They originally thought that Earth-like stars should be covered with large and small craters left by impacts, and then used the "craters" left per unit area to estimate the age of the planet's outer shell. But in fact, there are so few craters on the surface of Io that there are only a handful of them. This surface appears to be very young.
In addition to craters, Voyager 1 discovered hundreds of calderas, some of which are still active! Feather-like ejecta reaches heights of 300 kilometers, and these stunning photos were taken back by the Galileo (below) and Voyager (right) spacecraft. This may be the single most important discovery of the Voyager mission, the first practical demonstration of the heat and activity inside an Earth-like star. The material appears to be ejected from the crater in the form of sulfur or sulfur dioxide. The eruption was quite rapid, but during the four months between the arrival of Voyager 1 and Voyager 2, some activity stopped and others started again. There are also visible changes in the accumulation around the vents.
Recent photos from NASA's Infrared Telescope Facility on Mauna Kea, Hawaii, show a new massive volcanic eruption on Io (right). New sightings in the Ra Patera region have been seen by the Hubble Telescope. Images from Galileo also show some changes to its surface since Voyager's contact with it. These observations prove that Io's surface is indeed quite active.
Io has an astonishing variety of terrain: there are volcanic craters thousands of meters deep, there are hot sulfur lakes (pictured below, right), and there are obvious non-volcanic stretches. Mountains (left), flowing hundreds of kilometers of viscous liquid (some form of sulfur?), and some volcanic vents. The many colors of sulfur and its compounds contribute to the diversity of colors on Io's surface.
Analysis of Voyager images has convinced scientists that the lava flows on Io's surface are mostly composed of hot sulfur compounds. However, subsequent surface-based studies have shown that temperatures there are too high for liquid sulfur to exist. One current theory is that Io's lava flows are made of hot silicate rock. Recent Hubble observations suggest that the material may be rich in sodium, or have different compositions in different places.
The hottest spot on Io's surface can reach temperatures of 1,500 K, although its average temperature is only about 130 K. These hot spots are the main reason Io loses its heat.
The energy required for all its activities may come from the tidal forces of its interactions with Europa, Ganymede and Jupiter. The orbital relationship of these three satellites is fixed. Io's orbital period is twice that of Europa, which is twice that of Ganymede. Although Io is like the Earth's satellite moon, with only one fixed side facing its host star, it is a little unstable due to the interaction between Europa and Ganymede. It twists and bends Io, which is about 100 meters long (a spring tide of 100!), and generates energy in the cycle of undoing the twist. (The moon is not heated by the Earth in this way because it lacks another star to disturb it.)
Io also cuts Jupiter's magnetic field lines, generating electric currents. The resulting energy is not much for tidal forces, but the current has a power of 1 megawatt. It also stripped away some of Io's material and produced a strong bulge of radiation around Jupiter. Particles breaking off in the bulge are partly responsible for Jupiter's massive magnetosphere.
Recent data from Galileo suggest that Io may have its own magnetic field, like Ganymede.
Io has a thin atmosphere composed of sulfur dioxide and other gases.
Unlike other moons discovered by Galileo, Io has almost no water. This may be because in the early stages of the evolution of the solar system, Jupiter was too hot, causing the volatile materials near Io to evaporate, but it was not overheated and squeezed out all the water.
Stars
Looking at the night sky from the earth, the universe is a world of stars.
The distribution of stars in the universe is uneven. From the day they were born, they have gathered in groups, reflected each other, and formed binary stars, star clusters, and galaxies...
Stars are burning planets. Generally speaking, stars are relatively large in size and mass. It is only because they are so far away from the earth that the starlight appears so weak.
Ancient astronomers believed that the position of a star in the starry sky was fixed, so they named it "Xingxing", which means "eternal star". But we know today that they are constantly moving at high speed. For example, the sun moves the entire solar system around the center of the Milky Way. But other stars are so far away from us that we can hardly detect changes in their positions.
Stars have strong or weak abilities to emit light. In astronomy, it is represented by "luminosity". The so-called "luminosity" refers to the power radiated in the form of light from the surface of the star. Star surface temperatures also vary from high to low. Generally speaking, the lower the temperature of a star's surface, the redder its light is; the higher the temperature, the bluer its light. The higher the surface temperature, the larger the surface area, and the greater the luminosity. From the color and luminosity of stars, scientists can extract a lot of useful information.
Historically, the astronomer Hertzsprung and the philosopher Russell first proposed the relationship between star classification, color and luminosity, established the stellar evolution relationship known as the "Hertz-Router diagram", and revealed the relationship between star classification and color and luminosity. The secrets of stellar evolution. In the "H-Ro diagram", from the high temperature and strong luminosity area on the upper left to the low temperature and weak luminosity area on the lower right, there is a narrow star-dense area, including our sun; this sequence is called the main sequence , more than 90% of stars are concentrated in the main sequence. Above the main sequence region are the giant and supergiant regions; on the lower left is the white dwarf region.
Stars are born from interstellar dust in space (scientists vividly call them "nebulae" or "interstellar clouds").
The "youth" of a star is the longest golden stage in its life - the main sequence stage, which accounts for 90% of its entire life. During this time, the star glows and heats with almost constant luminosity, illuminating the surrounding space.
After this, the star will become turbulent and turn into a red giant; then, the red giant will complete its entire mission in an explosion, ejecting most of its material back into space, The debris left behind may be a white dwarf, a neutron star, or even a black hole...
In this way, the star comes from the nebula and returns to the nebula, completing its glorious life.
The gorgeous stars will always be the most beautiful sight in the night sky.
Nebulae are the remnants of exploding stars.
The solar system is a celestial system composed of the sun, planets and their satellites, asteroids, comets, meteors and interplanetary materials. The sun is the center of the solar system.
In the huge solar system family, the mass of the sun accounts for 99.8% of the total mass of the solar system, and the nine major planets and tens of thousands of asteroids account for a negligible proportion. They revolve around the sun along their own orbits for eternity. At the same time, the sun generously and selflessly contributes its light and heat, warming every member of the solar system and promoting their continuous development and evolution.
In this family, the planet closest to the sun is Mercury, followed in order outward by Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto. Among them, only five can be seen with the naked eye. Countries have different names for these five stars. Ancient my country had the Five Elements Theory, so they used the five elements of gold, wood, water, fire, and earth to name them Venus, Jupiter, Mercury, Mars and Saturn are not so called because there is water on Mercury and trees on Jupiter. In Europe, they call them after Roman mythological characters. The three far-solar planets discovered in modern times are called in the West by the names of the God of the Sky, the God of the Sea, and the God of the Underworld in accordance with the tradition of naming them after mythical figures. In Chinese, they are translated as Uranus, Neptune, and Pluto accordingly.
The nine planets and the sun are ordered from largest to smallest in size: the sun, Jupiter, Saturn, Uranus, Neptune, Earth, Venus, Mars, Mercury, and Pluto. They can be roughly divided into three categories according to standards such as mass, size, chemical composition, and distance from the sun: terrestrial planets (Mercury, Venus, Earth, Mars); giant planets (Jupiter, Saturn); aphelion planets ( Uranus, Neptune, Pluto〉. They have the characteristics of surface, isotropic, and nearly circularity during revolution. There are hundreds of thousands of asteroids of different sizes and shapes between Mars and Jupiter. Astronomy calls this area the asteroid belt. In addition, the solar system also includes many comets and countless extraterrestrial visitors - meteors.
The solar system is a celestial system composed of the sun, planets and their satellites, asteroids, comets, meteors and interplanetary materials. The sun is the center of the solar system. In the huge solar system family, the mass of the sun accounts for 99.8% of the total mass of the solar system, and the nine major planets and tens of thousands of asteroids account for a negligible proportion. They revolve around the sun along their own orbits for eternity. At the same time, the sun generously and selflessly contributes its light and heat, warming every member of the solar system and promoting their continuous development and evolution.
In this family, the planet closest to the sun is Mercury, followed in order outward by Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto. Among them, only five can be seen with the naked eye. Countries have different names for these five stars. Ancient my country had the Five Elements Theory, so they used the five elements of gold, wood, water, fire, and earth to name them Venus, Jupiter, Mercury, Mars and Saturn are not so called because there is water on Mercury and trees on Jupiter. In Europe, they call them after Roman mythological characters. The three far-solar planets discovered in modern times are called in the West by the names of the God of the Sky, the God of the Sea, and the God of the Underworld in accordance with the tradition of naming them after mythical figures. In Chinese, they are translated as Uranus, Neptune, and Pluto accordingly.
The nine planets and the sun are ordered from largest to smallest in size: the sun, Jupiter, Saturn, Uranus, Neptune, Earth, Venus, Mars, Mercury, and Pluto. They can be roughly divided into three categories according to standards such as mass, size, chemical composition, and distance from the sun: terrestrial planets (Mercury, Venus, Earth, Mars); giant planets (Jupiter, Saturn); aphelion planets ( Uranus, Neptune, Pluto〉. They have the characteristics of surface, isotropic, and nearly circularity during revolution. There are hundreds of thousands of asteroids of different sizes and shapes between Mars and Jupiter. Astronomy calls this area the asteroid belt. In addition, the solar system also includes many comets and countless extraterrestrial visitors - meteors.
The solar system is a celestial system composed of the sun, planets and their satellites, asteroids, comets, meteors and interplanetary materials. The sun is the center of the solar system. In the huge solar system family, the mass of the sun accounts for 99.8% of the total mass of the solar system, and the nine major planets and tens of thousands of asteroids account for a negligible proportion. They revolve around the sun along their own orbits for eternity. At the same time, the sun generously and selflessly contributes its light and heat, warming every member of the solar system and promoting their continuous development and evolution.
In this family, the planet closest to the sun is Mercury, followed in order outward by Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto. Among them, only five can be seen with the naked eye. Countries have different names for these five stars. Ancient my country had the Five Elements Theory, so they used the five elements of gold, wood, water, fire, and earth to name them Venus, Jupiter, Mercury, Mars and Saturn are not so called because there is water on Mercury and trees on Jupiter. In Europe, they call them after Roman mythological characters. The three far-solar planets discovered in modern times are called in the West by the names of the God of the Sky, the God of the Sea, and the God of the Underworld in accordance with the tradition of naming them after mythical figures. In Chinese, they are translated as Uranus, Neptune, and Pluto accordingly.
The nine planets and the sun are ordered from largest to smallest in size: the sun, Jupiter, Saturn, Uranus, Neptune, Earth, Venus, Mars, Mercury, and Pluto. They can be roughly divided into three categories according to standards such as mass, size, chemical composition, and distance from the sun: terrestrial planets (Mercury, Venus, Earth, Mars); giant planets (Jupiter, Saturn); aphelion planets ( Uranus, Neptune, Pluto〉. They have the characteristics of surface, isotropic, and nearly circularity during revolution. There are hundreds of thousands of asteroids of different sizes and shapes between Mars and Jupiter. Astronomy calls this area the asteroid belt. In addition, the solar system also includes many comets and countless extraterrestrial visitors - meteors.
The solar system is a celestial system composed of the sun, planets and their satellites, asteroids, comets, meteors and interplanetary materials. The sun is the center of the solar system. In the huge solar system family, the mass of the sun accounts for 99.8% of the total mass of the solar system, and the nine major planets and tens of thousands of asteroids account for a negligible proportion. They revolve around the sun along their own orbits for eternity. At the same time, the sun generously and selflessly contributes its light and heat, warming every member of the solar system and promoting their continuous development and evolution.
In this family, the planet closest to the sun is Mercury, followed in order outward by Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto. Among them, only five can be seen with the naked eye. Countries have different names for these five stars. Ancient my country had the Five Elements Theory, so they used the five elements of gold, wood, water, fire, and earth to name them Venus, Jupiter, Mercury, Mars and Saturn are not so called because there is water on Mercury and trees on Jupiter. In Europe, they call them after Roman mythological characters. The three far-solar planets discovered in modern times are called in the West by the names of the God of the Sky, the God of the Sea, and the God of the Underworld in accordance with the tradition of naming them after mythical figures. In Chinese, they are translated as Uranus, Neptune, and Pluto accordingly.
The nine planets and the sun are ordered from largest to smallest in size: the sun, Jupiter, Saturn, Uranus, Neptune, Earth, Venus, Mars, Mercury, and Pluto. They can be roughly divided into three categories according to standards such as mass, size, chemical composition, and distance from the sun: terrestrial planets (Mercury, Venus, Earth, Mars); giant planets (Jupiter, Saturn); aphelion planets ( Uranus, Neptune, Pluto〉. They have the characteristics of surface, isotropic, and nearly circularity during revolution. There are hundreds of thousands of asteroids of different sizes and shapes between Mars and Jupiter. Astronomy calls this area the asteroid belt. In addition, the solar system also includes many comets and countless extraterrestrial visitors - meteors.
The solar system is a celestial system composed of the sun, planets and their satellites, asteroids, comets, meteors and interplanetary materials. The sun is the center of the solar system. In the huge solar system family, the mass of the sun accounts for 99.8% of the total mass of the solar system, and the nine major planets and tens of thousands of asteroids account for a negligible proportion. They revolve around the sun along their own orbits for eternity. At the same time, the sun generously and selflessly contributes its light and heat, warming every member of the solar system and promoting their continuous development and evolution.
In this family, the planet closest to the sun is Mercury, followed in order outward by Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto.
Among them, only five can be seen with the naked eye. Countries have different names for these five stars. Ancient my country had the Five Elements Theory, so they used the five elements of gold, wood, water, fire, and earth to name them Venus, Jupiter, Mercury, Mars and Saturn are not so called because there is water on Mercury and trees on Jupiter. In Europe, they call them after Roman mythological characters. The three far-solar planets discovered in modern times are called in the West by the names of the God of the Sky, the God of the Sea, and the God of the Underworld in accordance with the tradition of naming them after mythical figures. In Chinese, they are translated as Uranus, Neptune, and Pluto accordingly.
The nine planets and the sun are ordered from largest to smallest in size: the sun, Jupiter, Saturn, Uranus, Neptune, Earth, Venus, Mars, Mercury, and Pluto. They can be roughly divided into three categories according to standards such as mass, size, chemical composition, and distance from the sun: terrestrial planets (Mercury, Venus, Earth, Mars); giant planets (Jupiter, Saturn); aphelion planets ( Uranus, Neptune, Pluto〉. They have the characteristics of surface, isotropic, and nearly circularity during revolution. There are hundreds of thousands of asteroids of different sizes and shapes between Mars and Jupiter. Astronomy calls this area the asteroid belt. In addition, the solar system also includes many comets and countless extraterrestrial visitors - meteors.
The solar system is a celestial system composed of the sun, planets and their satellites, asteroids, comets, meteors and interplanetary materials. The sun is the center of the solar system. In the huge solar system family, the mass of the sun accounts for 99.8% of the total mass of the solar system, and the nine major planets and tens of thousands of asteroids account for a negligible proportion. They revolve around the sun along their own orbits for eternity. At the same time, the sun generously and selflessly contributes its light and heat, warming every member of the solar system and promoting their continuous development and evolution.
In this family, the planet closest to the sun is Mercury, followed in order outward by Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto. Among them, only five can be seen with the naked eye. Countries have different names for these five stars. Ancient my country had the Five Elements Theory, so they used the five elements of gold, wood, water, fire, and earth to name them Venus, Jupiter, Mercury, Mars and Saturn are not so called because there is water on Mercury and trees on Jupiter. In Europe, they call them after Roman mythological characters. The three far-solar planets discovered in modern times are called in the West by the names of the God of the Sky, the God of the Sea, and the God of the Underworld in accordance with the tradition of naming them after mythical figures. In Chinese, they are translated as Uranus, Neptune, and Pluto accordingly.
The nine planets and the sun are ordered from largest to smallest in size: the sun, Jupiter, Saturn, Uranus, Neptune, Earth, Venus, Mars, Mercury, and Pluto. They can be roughly divided into three categories according to standards such as mass, size, chemical composition, and distance from the sun: terrestrial planets (Mercury, Venus, Earth, Mars); giant planets (Jupiter, Saturn); aphelion planets ( Uranus, Neptune, Pluto〉. They have the characteristics of surface, isotropic, and nearly circularity during revolution. There are hundreds of thousands of asteroids of different sizes and shapes between Mars and Jupiter. Astronomy calls this area the asteroid belt. In addition, the solar system also includes many comets and countless extraterrestrial visitors - meteors. The solar system is a celestial system composed of the sun, planets and their satellites, asteroids, comets, meteors and interplanetary materials. The sun is the center of the solar system. In the huge solar system family, the mass of the sun accounts for 99.8% of the total mass of the solar system, and the nine major planets and tens of thousands of asteroids account for a negligible proportion. They revolve around the sun along their own orbits for eternity. At the same time, the sun generously and selflessly contributes its light and heat, warming every member of the solar system and promoting their continuous development and evolution.
In this family, the planet closest to the sun is Mercury, followed in order outward by Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto. Among them, only five can be seen with the naked eye. Countries have different names for these five stars. Ancient my country had the Five Elements Theory, so they used the five elements of gold, wood, water, fire, and earth to name them Venus, Jupiter, Mercury, Mars and Saturn are not so called because there is water on Mercury and trees on Jupiter. In Europe, they call them after Roman mythological characters.
The three far-solar planets discovered in modern times are called in the West by the names of the God of the Sky, the God of the Sea, and the God of the Underworld in accordance with the tradition of naming them after mythical figures. In Chinese, they are translated as Uranus, Neptune, and Pluto accordingly.
The nine planets and the sun are ordered from largest to smallest in size: the sun, Jupiter, Saturn, Uranus, Neptune, Earth, Venus, Mars, Mercury, and Pluto. They can be roughly divided into three categories according to standards such as mass, size, chemical composition, and distance from the sun: terrestrial planets (Mercury, Venus, Earth, Mars); giant planets (Jupiter, Saturn); aphelion planets ( Uranus, Neptune, Pluto〉. They have the characteristics of surface, isotropic, and nearly circularity during revolution. There are hundreds of thousands of asteroids of different sizes and shapes between Mars and Jupiter. Astronomy calls this area the asteroid belt. In addition, the solar system also includes many comets and countless extraterrestrial visitors - meteors.
The Milky Way
The star system in which the solar system is located includes one to two hundred billion stars and a large number of star clusters, nebulae, as well as various types of interstellar gas and interstellar dust. Its total mass is 140 billion times the mass of the sun. Most stars in the Milky Way are concentrated in an oblate spheroid of space, shaped like a discus. The protruding part in the middle of the oblate spheroid is called the "nuclear bulge", with a radius of about 7,000 light-years. The middle part of the nuclear ball is called the "silver core" and the surrounding area is called the "silver plate". There is a larger sphere outside the galactic disk, where there are few stars and low density, called the "galactic halo", with a diameter of 70,000 light-years. The Milky Way is a spiral galaxy with a spiral structure, that is, it has a galactic center and two spiral arms. The spiral arms are 4,500 light years apart. The rotation speed and period of each part vary depending on the distance from the galactic center. The sun is about 23,000 light-years away from the center of the galaxy, orbiting the center of the galaxy at a speed of 250 kilometers per second, with a period of about 250 million years.
Universe
The day when the energy in all matter in the universe is exhausted, that is when the material universe dies. All matter in the universe is decomposed into a prison field ("yin") and an energy field ("yang"). At this time, the temperature of the universe is the lowest; the average energy density is the lowest; the universe expands to its maximum; naked singularity black holes are farthest from each other; The potential energy of original gravity reaches its maximum. At this time, the universe was completely dark, and the universe expanded to the largest torus. The torus was covered with billions of dead galaxies that had degenerated into naked singularity prison fields or dark galaxies. This is the end of the physical universe.
Meteor
When a meteor swarm meets the Earth, the number of meteors increases significantly within a few hours to a few days, sometimes even like rain. This phenomenon is called a meteor shower. The trajectories of the meteors observed during a meteor shower are extended in the opposite direction, and they all intersect at a point, which is called the radiant point. Most meteor showers are named after the bright stars in or near the constellation where the radiant point is located, such as the "Leonids". A few meteor showers are named after comets with which they are associated, such as the Comet Beela meteor shower. When a meteor shower occurs, the appearance rate of meteors is usually a dozen to dozens per hour, but in rare cases it can reach tens of thousands per hour. This is called a meteor storm. Meteor showers are a periodic phenomenon, and the dates of occurrence are basically fixed. However, because the meteoroids in the meteor group are very unevenly distributed in orbit, the number of meteors in the meteor showers varies every year. For example, the Leonid meteor shower is generally smaller in scale every year, and Every 33 years, there will be a meteor storm of varying degrees
Meteorites
Meteorites are "guests" from outside the earth. According to the different chemical components of the meteorite itself, it can be roughly divided into three types:
1. Iron meteorite, also called meteorite, its main components are iron and nickel;
< p>2. Stony iron meteorites, also called tektites, are relatively rare, in which iron, nickel and silicate account for roughly half each;3. Stony iron meteorites, also called meteorites, are mainly composed of: Silicates, the most abundant type of meteorite.
Meteorites contain a large amount of rich information on the formation and evolution of solar system objects. Experimental analysis of them will help explore the mysteries of the evolution of the solar system. Meteorites are composed of chemical elements known to Earth, and water and a variety of organic compounds are found in some meteorites. This becomes a basis for the hypothesis of the origin of life that "life on earth was caused by meteorites spreading the seeds of life to the earth." By measuring the isotope content of various elements in meteorites, the age of the meteorite can be deduced, and thus the period when the solar system began to form.
Meteorites may be fragments produced after the breakup of asteroids, planets, large satellites or comets, and they can carry original information about these celestial bodies. Famous meteorites include the Jilin meteorite in China, the Xinjiang meteorite in China, the Ballinger meteorite in the United States, and the Murchison carbonaceous meteorite in Australia.
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Reference materials: books