[Solar system]
(Note: In Resolution 5, adopted at the 26th International Astronomical Union in Prague on August 24, 2006, Pluto was classified as a dwarf planet and named Asteroid 134340, and removed from the nine planets of the Solar System. Therefore, there are now only eight planets in the Solar System. (All references to "nine planets" in the text have been changed to "eight planets").
The solar system consists of the Sun, nine planets, 66 moons, and countless asteroids, comets, and meteorites. The order of the planets from the sun outward is: Mercury (mercury), Venus (venus), Earth (earth), Mars (mars), Jupiter (jupiter), Saturn (saturn), Uranus (uranus), Neptune (neptune) and Pluto (pluto). Closer to the Sun, Mercury, Venus, Earth and Mars are called terrestrial planets. Spaceships have explored them all, and have also landed on Mars and Venus, obtaining important results. Their *** with the same characteristics is the density (& gt; 3.0 g / cm3), small volume, slow rotation, few satellites, the internal composition is mainly for the silicate (silicate), with a solid shell. Jupiter, Saturn, Uranus, Neptune and Pluto, which are farther away from the Sun, are called jovian planets. They have all been explored by spacecraft but have not landed. They all have thick atmospheres and their surface characteristics are difficult to understand, but it is generally assumed that they all have solid cores similar to the Earth-like planets. There are more than 100,000 asteroids (i.e., small irregular bodies of rock) between Mars and Jupiter. It is hypothesized that they may have broken up from one of the planets whose location bounds the boundary between Mars and Jupiter, or from some of the stony debris that failed to coalesce into a unified planet. Meteorites exist between the planets and are stony or iron in composition.
Star, Distance (AU), Radius (Earth), Mass (Earth), Orbital Inclination (degrees), Orbital Eccentricity, Tilt, Density (g/cm3)
Solaris, 0 , 109 , 332,800 , ---- , ---- , 1.410
Mercury, 0.39 , 0.38 , 0.05 , 7 . 0.2056 , 0.1° , 5.43
Venus , 0.72 , 0.95 , 0.89 , 3.394 , 0.0068 , 177.4° , 5.25
Earth , 1.0 , 1.00 , 1.00 , 0.000 , 0.0167 , 23.45° , 5.52
Mars , 1.5 . 0.53, 0.11, 1.850, 0.0934, 25.19°, 3.95
Jupiter , 5.2, 11.0, 318, 1.308, 0.0483, 3.12°, 1.33
Saturn , 9.5, 9.5, 95, 2.488, 0.0560, 26.73°, 0.69
< p>Uranus , 19.2 , 4.0 , 17 , 0.774 , 0.0461 , 97.86° , 1.29Neptune , 30.1 , 3.9 , 17 , 1.774 , 0.0097 , 29.56° , 1.64
Pluto , 39.5 , 0.18 , 0.002 , 17.15 , 0.2482 . 119.6° , 2.03
Of the nine planets, Mercury, Venus, Earth, and Mars are generally referred to as Earth-like planets, and are **** alike in that they are characterized by their predominantly stony and ferruginous composition, and by their smaller radii and masses, but higher densities. Jupiter, Saturn, Uranus and Neptune are called Jupiter-like planets, their ****similar characteristics are that they are mainly composed of hydrogen, helium, ice, methane, ammonia, etc., with a very small proportion of stony and iron, and their masses and radii are much larger than the Earth's, but their densities are lower. Pluto is a special planet. The distance of the planets from the sun has a regularity, that is, calculated from near to far from the sun, the distance of the planets to the sun (expressed as a) a = 0.4 + 0.3 * 2n-2 (astronomical units) where n indicates that the nth planet from near to far (see the table above for more details) The rotation period of the earth, mars, Jupiter, Saturn, Uranus, and Neptune is from 12 hours to about one day, but the rotation period of Mercury, Venus, and Pluto is are very long, 58.65, 243 and 6.387 days respectively, and most of the planets rotate in the same direction as the direction of rotation, but Venus is the opposite. Except for Mercury and Venus, all the other planets have satellites orbiting them, constituting a system of satellites.
In the solar system, more than 1600 comets have been discovered, roughly half of which are rotating around the Sun in the same direction, and the other half are rotating in the opposite direction. Comets show strange shape changes in their orbits around the Sun. There are also a large number of large and small meteoroids in our solar system, some of which are in clusters, and these clusters are the products of comet disintegration. Large meteoroids fall to the ground and become meteorites. The solar system is a very small part of the Milky Way, it is only one of hundreds of billions of stars in the Milky Way, it is about 8.5 kiloseconds away from the center of the Milky Way, that is, less than 30,000 light years. The Sun carries the entire solar system around the center of the Milky Way. It can be seen that the solar system is not in the center of the universe, nor is it in the center of the Milky Way. The Sun was formed 5 billion years ago by the collapse of a small cloud from the disintegration of the interstellar cloud, and it has a lifespan of about 10 billion years.
[Cosmic spaceflight]
The universe is a general term for the vast expanse of space and the variety of celestial bodies and diffuse matter that exists within it. The universe is the material world, which is in constant motion and development. For thousands of years, scientists have been exploring when and how the universe was formed. It is only today that scientists are convinced that the universe was formed by a big bang that occurred about 15 billion years ago. Before the explosion, all the matter and energy that existed within the universe came together and condensed into a very small volume that was extremely hot and dense, after which the Big Bang occurred. The big bang makes the material scattered out of the universe, the space continues to expand, the temperature also drops accordingly, and later appeared in the universe all the galaxies, stars, planets and even life, are in this continuous expansion and cooling process of gradual formation. However, the theory of the Big Bang and the creation of the universe can not yet explain exactly, "in the existing matter and energy gathered in a point" before what exists? The "Big Bang Theory" was created by Gamow in 1946.
Big Bang Theory
(big-bang cosmology) The most influential theory of the modern cosmos, also known as Big Bang cosmology. It accounts for more observational facts than other models of the universe. Its main idea is that our universe had a history of evolution from hot to cold. During this period, the cosmic system was not static, but was constantly expanding, causing the density of matter to evolve from dense to sparse. This process of going from hot to cold and from dense to rarefied was like an explosion of enormous proportions. According to the Big Bang cosmology, the whole process of the Big Bang is: in the early days of the universe, the temperature was extremely high, above 10 billion degrees. The density of matter is also quite large, the entire cosmic system reached equilibrium. The universe only neutrons, protons, electrons, photons and neutrinos and some other fundamental particles form of matter. But because the whole system is expanding, the result is that the temperature drops very quickly. When the temperature dropped to about 1 billion degrees, the neutron began to lose the conditions for free existence, and it either decayed or combined with protons to form elements such as heavy hydrogen and helium; the chemical elements began to form from this period. The early formation of chemical elements ends after a further drop in temperature to one million degrees (see theory of elemental synthesis). The matter in the universe consists mainly of protons, electrons, photons, and some relatively light atomic nuclei. When the temperature dropped to a few thousand degrees, the radiation receded, and the universe was dominated by gaseous matter, with the gases gradually coalescing into gas clouds, which further formed a variety of stellar systems that became the universe we see today. Big Bang model can be unified to illustrate the following observational facts:
(1) the Big Bang theory advocates that all stars are produced after the temperature drop, and therefore the age of any object should be shorter than since the temperature drop to today's period of time, that is, should be less than 20 billion years. Measurements of the ages of various objects have proved this.
(2) Extragalactic objects have been observed to have systematic spectral redshifts, and the redshifts are roughly proportional to the distance. If this is explained by the Doppler effect, then the redshift is a reflection of the expansion of the universe.
(3) Helium abundances are quite large on a variety of different objects, and are mostly 30%. Using the stellar nuclear reaction mechanism is not enough to explain why there is so much helium. Instead, the fact that, according to the Big Bang theory, the early temperatures were very high and the efficiency of helium production was very high would account for this fact.
(4) Based on the rate of expansion of the universe, as well as helium abundance, etc., it is possible to calculate the temperature of the universe specifically for each period of history. Gamow, one of the founders of the Big Bang theory, predicted that today's universe has been very cold, only a few degrees of absolute temperature. 1965, indeed, in the microwave band with a spectrum of thermal radiation detected in the microwave background radiation, the temperature of about 3K.
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Humans have wanted to take a dip in space for a long time, and the first Luna Park was opened on Earth in 1903. For 50 cents you could board a cigar-shaped, winged vehicle, which then rocked violently and ended up on a model of the moon.
That same year, the Wright Brothers clattered through the air for 59 seconds while a self-taught Russian named Konstantin Jau?kowski published an article titled Space Exploration by means of Reaction Instruments. In it, he calculated that a missile would have to travel at 18,000 miles per hour to overcome Earth's gravity. He also suggested the construction of a liquid-driven, multi-stage rocket.
In the 1950s, there was an accepted basic idea that whichever country was the first to succeed in building a permanent space station would sooner or later be able to control the entire planet. Von Braun described to Americans intercontinental missiles, submarine missiles, space mirrors, and possible trips to the moon. He had envisioned a cosmic space station that was frequently manned and capable of launching nuclear missiles. He said, "If one considers that the space station flies over all inhabited areas of the earth, then one can recognize that this technology of nuclear war would put the satellite makers in a position of absolute superiority in war.
In 1961, Gagarin became the first person to go into space. The Russians used him to show that it was not angels or God who flew around in the sky. John F. Kennedy's campaign slogan was "The New Frontier". He explained: "Once again we live in an age of discovery. Cosmic space is our immeasurable new frontier." For Kennedy, the Soviets' first foray into cosmic space was "the worst defeat the United States had experienced in years." The only way out was to attack and defend, and in 1958 the United States created NASA and launched its first satellite, Explorer, in the same year, and in 1962 John Glenn became the first American to orbit the Earth.
Many scientists were already skeptical of dangerous manned space flight, and preferred to use a vehicle to explore the solar system.
Instead, the Americans achieved a breakthrough: three astronauts flew around the Moon in the Apollo spacecraft. In this context, the first docking of two manned spacecraft, scheduled for January 1969, took on special significance.
In the 1980s, the Soviet Union's third-generation space station, the Mir orbital station, was the peak of its space activities, and it was an eye-opener for the Americans. "Peace" is known as the "man-made Tiangong", launched on February 20, 1986, is so far the only manned space orbital station in near-Earth space can operate for a long time. It is the only manned space orbital station in near-Earth space capable of long-term operation to date. It is connected to the "Quantum 1", "Quantum 2", "Crystal" and "Spectrum" modules, "Nature" module and other compartments to form a 140-ton, working volume of 400 cubic meters of the huge space orbit joint. In this "small factory in space" successive visits to the Russian and foreign cosmonauts 106, as many as 22,000 scientific research projects, 600 key projects.
The most fascinating experiment carried out on Mir was the extension of the duration of human stay in space. Extending the duration of human stay in space is the most critical step for mankind to fly out of its cradle on Earth and move towards Mars and other celestial bodies, and to solve this problem, it is necessary to overcome weightlessness, cosmic radiation and psychological barriers arising from human presence in space, and so on. Russian cosmonauts have made significant progress in this area, with cosmonaut Polyakov setting a record of 438 consecutive days of flight in a single mission on board Mir, which cannot but be regarded as an important achievement in the history of spaceflight in the twentieth century. A large number of life science experiments were conducted on the orbital station, such as the cultivation of quail, salamanders and growing wheat.
If the Mir space station is regarded as the third generation of human space stations, the ISS belongs to the fourth generation. The ISS project, which cost more than 60 billion dollars, is the largest human spaceflight project ever undertaken by mankind. It is from the initial conception and the final implementation of both the United States and the Soviet Union is the product of competition, but also the current U.S.-Russian cooperation, from the side of the refraction of the history of a process.
The implementation of the ISS program is divided into three phases. The first phase was the preparation phase that started in 1994 and has now been completed. During this period, the U.S. and Russia conducted a series of joint human spaceflight activities. U.S. Space Shuttle and Russia's "Peace" orbital station 8 docking and *** with the flight, the training of U.S. astronauts to live and work on the space station; the second phase began in November 1998: Russia's use of the "Proton -K "rocket to place the functional cargo module, the main module of the station, into orbit. It was also tasked with a number of military experiments, so that the module was to be used only by United States astronauts. The completion of the launch and docking of the experimental module will mark the end of the second stage, when the station will have taken shape and will be able to accommodate three astronauts on a permanent basis, and the third stage, when it will be necessary to send into space the U.S. habitation module, the experimental modules manufactured by the European Space Agency and Japan, and the Canadian mobile service system. When these compartments docked with the space station, it marks the final completion of the ISS assembly, when the astronauts on the station can be increased to seven people.
Fifteen countries, including the United States and Russia, have joined forces to build the ISS, heralding an era of exploration and peaceful exploitation of cosmic space by all nations***. However, the results of decades of human spaceflight activities are far from satisfying their thirst for space. "The road is long, I will go up and down to seek", mankind has always had the desire to conquer space and the determination to utilize space resources peacefully. in November 1998, the first American astronaut to enter the Earth's orbit, 77-year-old Glenn, set out on the space journey again with his undying ambition, which seemed to tell mankind: At this rate, the conquest of space is not a dream.
The origin of astronomy can be traced back to the budding era of human culture. In ancient times, people observed the sun, the moon and the stars in order to indicate direction, determine time and seasons, determine their positions, find out their changing patterns, and compile calendars accordingly. From this point of view, astronomy is one of the oldest natural science disciplines.
Early astronomy was, by its very nature, astrometry. From the middle of the sixteenth century, when Copernicus put forward the doctrine of heliocentric system, the development of astronomy entered a completely new stage. Previously the natural sciences, including astronomy, were severely bound by religious theology. Copernicus's doctrine freed astronomy from the shackles of religion, and in the century and a half since then it has evolved from classical astrometry, which mainly describes purely the positions and motions of celestial bodies, to celestial mechanics, which seeks to find the mechanisms that cause the mechanics of such motions.
Polish astronomer and founder of heliocentrism, Nicolaus Copernicus (1473-1543).
Galileo Galilei (1564-1642), Italian astronomer who made the first astronomical telescope.
Galileo with his assistants.
Kepler (1571-1630), the famous German astronomer.
Newton (1642-1727), the famous physicist who invented the reflecting telescope.
English astronomer Halley (1656-1742).
French astronomer Mercier (1730-1817).
William Herschel (1738-1822), British astronomer and discoverer of Uranus.
American astronomer Edwin Hubble (1889-1953).
Famous physicist Albert Einstein (1879-1955).
American engineer Yansky, the founder of radio astronomy, who worked on radio.
Subramanian Chandrasekhar (1910-1995), astronomer.
The eighteenth and nineteenth centuries saw the heyday of classical celestial mechanics. At the same time, due to the widespread use of spectroscopy, photometry and photography, astronomy began to develop towards an in-depth study of the physical structure and physical processes of celestial bodies, giving birth to astrophysics. In the twentieth century, modern physics and technology developed highly and found a broad place in astronomical observation and research, making astrophysics a mainstream discipline in astronomy, and at the same time prompting the classical celestial mechanics and astrometry to have a new development, and people's understanding of the universe and all kinds of celestial bodies in the universe and astronomical phenomena has reached unprecedented depth and breadth.
Astronomy is essentially an observational science. All discoveries and research results in astronomy cannot be separated from the astronomical observation tools - telescopes and their back-end receiving equipment. In the seventeenth century, although people have made a lot of astronomical observation instruments, such as China's hunyi, simple instrument, but the observation work can only rely on the naked eye. 1608, the Dutchman Li Polsay invented the telescope, 1609 Galileo made the first astronomical telescope, and made a lot of important discoveries, from the time astronomical across the telescope into the era. Since then, the performance of the telescope has been improved continuously, in order to observe fainter celestial bodies and achieve higher resolution. 1932, the American Yansky used his rotating antenna array to observe the radio waves from celestial bodies, which created radio astronomy. 1937 saw the birth of the first parabolic reflector radio telescope. Afterwards, with the continuous expansion and improvement of radio telescopes in terms of aperture and receiving wavelength, sensitivity and other properties, radio astronomy observation technology has made important contributions to the development of astronomy. In the last 50 years of the twentieth century, with the development of detectors and space technology as well as in-depth research, astronomical observation was further expanded from visible light and radio bands to various bands of electromagnetic waves, including infrared, ultraviolet, X-rays and γ-rays, forming multi-band astronomy and providing powerful observation means for exploring various types of celestial bodies and the physical nature of astronomical phenomena, and the development of astronomy has reached a completely new The development of astronomy has reached a completely new stage.
At the back end of the telescope receiving equipment, in the middle of the nineteenth century, photographic, spectroscopic and photometric techniques were widely used in astronomical observation, which played a great role in exploring the motion, structure, chemical composition and physical state of celestial bodies, and it can be said that astrophysics has gradually developed into a mainstream discipline of astronomy after the application of these techniques.
Astronomy is different from meteorology in that its object of study is the nature of the various types of celestial bodies outside the Earth's atmosphere and the various phenomena occurring on the celestial bodies - celestial phenomena, while the object of meteorological research is the various phenomena occurring within the Earth's atmosphere - meteorology. An exception is the Hong Kong Observatory, which also broadcasts frequent typhoon warnings.
Astronomy involves the study of various objects in cosmic space, ranging from the Moon, the Sun, planets, stars, galaxies, extragalactic galaxies, and the entire universe, to asteroids, meteoroids, and even dust particles of various sizes distributed throughout the vastness of cosmic space. Astronomers refer to all these objects collectively as celestial bodies. The Earth is also a celestial body, but astronomy only studies the general nature of the Earth and generally does not discuss its details. In addition, the nature of the motion of man-made vehicles such as artificial satellites, spacecraft, and space stations also falls within the scope of astronomical study and can be called man-made celestial bodies.
The celestial bodies in the universe can be divided into several levels from near to far: (1) solar system objects: including the sun, planets (including the earth), the satellites of the planets (including the moon), asteroids, comets, meteoroids and interplanetary medium. (2) Various types of stars and stellar groups in the Milky Way: including variable stars, binaries, cluster stars, star clusters, nebulae, and the interstellar medium. The Sun is an ordinary star in the Milky Way. (3) Extragalactic galaxies, or galaxies for short, refer to massive star systems located outside our Milky Way that are similar to our Milky Way, as well as larger groups of objects composed of galaxies, such as binary galaxies, multiple galaxies, clusters of galaxies, and superclusters of galaxies. There is also an intergalactic medium distributed between galaxies.
Astronomy also explores the origin, structure, evolution, and future end of the entire universe as we currently observe it in a general way, which is the study of cosmology, a subdiscipline of astronomy. Astronomy can also be divided into three subdisciplines, astrometry, celestial mechanics and astrophysics, in accordance with the content of the study.
Astronomy has always been the forerunner of philosophy, and it has always stood at the forefront of controversy. As a basic research discipline, astronomy is in many ways closely related to human society. Time, the alternation of day and night, the strict laws of the four seasons must be determined by astronomical methods. As mankind has entered the space age, astronomy plays an irreplaceable role in the successful conduct of all kinds of space exploration. Astronomy also makes its own contribution to disaster prevention and mitigation for mankind and the Earth. Astronomers will also pay close attention to catastrophic astronomical events - such as possible collisions between comets and the Earth - and make timely preventive and corresponding countermeasures.
Nine planets
Objects and contents of astronomical research
The object of astronomical research involves all kinds of stars and objects in the cosmic space, as big as the moon, the sun, the planets, the stars, the Milky Way, the extragalactic star systems and even the whole universe, and as small as the asteroids, meteoroids and even the large and small dust particles distributed in the vast cosmic space. Astronomers refer to all these stars and objects collectively as celestial bodies. In this sense, the Earth should also be a celestial body, but astronomy only studies the general nature of the Earth and generally does not discuss its details. On the other hand, the nature of the movement of artificial satellites, spacecraft, space stations and other artificial vehicles also belongs to the scope of the study of astronomy, can be called man-made objects.
Many people are often unable to tell the difference between astronomy and meteorology, and it is not uncommon for people to call the observatory to ask about the weather. Perhaps astronomy and meteorology are the study of the "sky" and make people confused, and the Hong Kong Observatory often broadcast typhoon warnings more people mistakenly think that the Observatory is the study of weather conditions. In fact, the "sky" studied in astronomy and the "sky" studied in meteorology are two completely different concepts. The "sky" in astronomy refers to the cosmic space, while the "sky" in meteorology is the earth's atmosphere. Astronomers study the nature of various types of celestial bodies outside the Earth's atmosphere and the various phenomena occurring on them - celestial phenomena, while meteorologists study the various phenomena occurring within the Earth's atmosphere - meteorology. Therefore, it is the business of astronomers to forecast the occurrence of solar and lunar eclipses and the appearance of meteor showers, while it is the duty of meteorologists to forecast typhoons, high temperatures, and cold waves. Keeping this in mind, it is not difficult to distinguish between astronomy and meteorology.
We can categorize the objects in the universe from near to far into several levels:
(1) Solar system objects: including the Sun, planets (including the Earth), satellites of planets (including the Moon), asteroids, comets, meteoroids, and interplanetary medium, etc.
(1) Solar system objects: including the Sun, planets (including the Earth), satellites of planets (including the Moon), asteroids, comets, meteoroids, and interplanetary medium.
(2) all kinds of stars and stellar groups in the Milky Way: including variable stars, binaries, cluster stars, star clusters, nebulae, and interstellar medium. The Sun is an ordinary star in the Milky Way.
(3) Extragalactic galaxies, or galaxies for short, refer to the massive stellar systems located outside our Milky Way that are similar to our Milky Way, as well as larger groups of objects composed of galaxies, such as binary galaxies, multiple galaxies, clusters of galaxies, and clusters of superclusters of galaxies. There is also an intergalactic medium distributed between galaxies.
Astronomy also explores in general terms the origin, structure, evolution, and future end of the entire universe as we currently observe it, which is the study of cosmology, a subdiscipline of astronomy.
Astronomy can be divided into three subdisciplines, astrometry, celestial mechanics, and astrophysics, according to the content of the study. Astrometry is the earliest branch of astronomy, its main content is to study and determine the position and motion of various types of celestial bodies, the establishment of the celestial sphere reference system. Observations obtained by astrometric methods can be used not only for celestial mechanics and astrophysical research, but also for applied purposes, such as determining the position of ground points. At present, the means of astrometry has been developed from the early single visible wavelengths to other electromagnetic wavelengths such as radio and infrared, and the accuracy has been improved, and extended from the ground to space, which is space astrometry.
Celestial mechanics mainly studies the interaction, motion and shape of celestial bodies, of which the motion should include the rotation of celestial bodies. Early studies were of solar system objects, and have now been extended to stars, star clusters and galaxies. The establishment of Newton's law of universal gravitation and the three laws of motion laid the foundations of celestial mechanics and led to the development of research from kinematics to dynamics. Therefore, it can actually be said that Newton was the founder of celestial mechanics. Today, we can accurately predict solar eclipses, lunar eclipses and other celestial phenomena, and the development of celestial mechanics is inseparable.
Astrophysics is the youngest branch of astronomy, which applies the techniques, methods, and theories of physics to study the morphology, structure, distribution, chemical composition, physical state and properties of various types of celestial bodies, as well as their evolutionary laws. In the eighteenth century, Herschel created stellar astronomy, which can be regarded as the gestation period of astrophysics. In the middle of the nineteenth century, with the development of astronomical observation technology, astrophysics has become an independent sub-discipline of astronomy, and prompted astronomical observation and research to continuously make new discoveries and new results. In terms of its research content, there are solar physics, solar system physics, stellar physics, galactic astronomy, galactic astronomy, cosmochemistry, celestial evolution and cosmology, etc.; in terms of its research methods can be divided into measured astrophysics and theoretical astrophysics.
A Brief History of Astronomy
The origin of astronomy can be traced back to the budding of human culture. In ancient times, in order to indicate the direction and determine the time and seasons, people naturally observed the position of the sun, moon and stars in the sky, found out its law of change over time, and compiled calendars on the basis of them for their life and agricultural and animal husbandry production activities. From this point of view, astronomy is one of the oldest natural science disciplines. The content of early astronomy was by its very nature astrometry.
From the middle of the sixteenth century, when Copernicus proposed the heliocentric system, the development of astronomy entered a completely new phase. Before that, natural science, including astronomy, was severely bound by religious theology. Copernicus's doctrine freed astronomy from the bondage of religion, and in the century and a half that followed, it developed from classical astrometry, which was mainly purely descriptive of the positions and motions of celestial bodies, to celestial mechanics, which sought to create a mechanism for the mechanics of such motions. In the eighteenth and nineteenth centuries, classical celestial mechanics reached its heyday. At the same time, due to the widespread use of spectroscopy, photometry and photogrammetry, astronomy began to develop towards an in-depth study of the physical structure and physical processes of celestial bodies, giving birth to astrophysics. In the twentieth century, modern physics and technology developed to a high degree, and found a broad place for astronomical observation and research, making astrophysics a mainstream discipline in astronomy, and at the same time prompting the classical celestial mechanics and astrometry also had a new development, people's understanding of the universe and the universe of various types of celestial bodies and astronomical phenomena has reached an unprecedented depth and breadth.
Astronomy is essentially an observational science. All discoveries and research results in astronomy cannot be separated from the astronomical observation tools - telescopes and telescopes receiving equipment. In the seventeenth century, although people have made a lot of astronomical observation instruments, such as in China has a hunyi, simple meter, etc., but the observation work can only rely on the human eye. 1608, the Dutchman Li Boerse invented the telescope, 1609 Galileo made the first astronomical telescope, and soon made a lot of important discoveries, from the astronomy across the telescope observation, the study of the heavens in the new era. In the nearly 400 years since then, the performance of telescopes has been continuously improved and made larger and larger, with a view to observing fainter celestial bodies and achieving higher resolution. The world's largest optical telescope now has an aperture of 10 meters.
In 1932, the American Yansky used his rotating antenna array to observe radio waves from celestial bodies, creating radio astronomy. 1937 saw the birth of the first parabolic reflector radio telescope. Afterwards, with the continuous expansion and improvement of radio telescopes in terms of aperture and receiving wavelength, sensitivity and other properties, radio astronomy observation technology has made important contributions to the development of astronomy. At present, the world's largest fully movable radio telescope diameter of 100 meters, the largest fixed radio telescope diameter of 300 meters.
In the last 50 years of the twentieth century, with the development of detectors and space technology as well as the depth of the research work, astronomical observation was further expanded from visible light and radio bands to include infrared, ultraviolet, X-rays and γ-rays, including the various bands of electromagnetic waves, forming a multiband astronomy, and for the exploration of various types of celestial bodies and the physical nature of astronomical phenomena to provide a powerful means of observation, the development of astronomy The development of astronomy has reached a completely new stage.
In terms of receiving equipment at the back end of the telescope, in the middle of the nineteenth century, photographic, spectroscopic and photometric techniques were widely used in astronomical observation, which played a great role in exploring the motion, structure, chemical composition and physical state of celestial bodies, and it can be said that astrophysics has gradually developed into a mainstream discipline of astronomy precisely after the application of these techniques. In the twentieth century, polarization observation, interferometry, speckle interference, CCD detectors, and multi-fiber optics have played an increasing role in astronomical observation. Undoubtedly, important achievements in astronomical research have been closely linked to the development and improvement of back-end detection equipment.
Some people may ask, since the objects of astronomical research are the stars, the sun, and the moon, what is the relationship between astronomy and the life and work of human beings on our planet? In fact, as a basic research discipline, much of what is currently being studied in the discipline of astronomy seems to have little to do with us humans in a short period of time. For example, the study of such basic questions as how the Milky Way moves obviously has little to do with our lives. But, on the other hand, the work of astronomers is in many ways closely related to human society.
Human life and work are inseparable from time, and the alternation of day and night, the four seasons of the strict law must be determined by astronomical methods, which is the problem of time and calendar. If there is no unified standard time system in the world and no perfect calendar, all kinds of social activities of human beings will not be able to carry out in an orderly manner, and everything will be in a state of confusion.
Humankind has entered the space age. The launch of various artificial Earth satellites, lunar probes or planetary probes, in addition to technical assurance, these vehicles to be launched according to predetermined goals and success, inseparable from the calculation of their movement orbit and strict schedule arrangements, and these are precisely the astronomy is playing an irreplaceable role.
The Sun is the closest star to us, and its light and heat have fed the growth of everything on Earth, including humans, for billions of years. Once the sun is violently active, the earth's climate, radio communications, astronauts, life and work will have a significant impact, astronomers are duty-bound to undertake the monitoring of solar activity, forecasting work. Not only that, some of the major natural disasters occurring on Earth, such as earthquakes, El Ni?o phenomenon, etc., astronomers are also working hard for it, and make their own contribution to disaster prevention and mitigation.
The appearance of special celestial events, such as solar eclipses, lunar eclipses,