Astronomical data

When you look up at the sky, do you know what those shiny things are? Some are planets, but most of them are stars, and some are giant galaxies, each with hundreds of billions of stars. Astronomy is the study of planets, stars and galaxies in the universe. Astronomers' task is to explain all kinds of celestial bodies we see in the night sky, and they are also committed to understanding other things, such as the age of stars and their distance from the earth.

"Almost all branches of natural science study the phenomena on the earth, and only astronomy has been linked with the splendid starry sky that we can't reach since the day it was born. Astronomers observe radiation from planets, stars, galaxies and other celestial bodies, from interstellar molecules to the whole universe. Astronomers measure their positions, calculate their orbits, study their birth, evolution and death, and explore their energy mechanisms. Astronomy, like physics, mathematics, geography and biology, is a basic subject.

The emergence of Newtonian mechanics, the discovery of nuclear energy and other events that play an important role in human civilization are closely related to astronomical research. At present, the study of high-energy astrophysics, compact stars and the evolution of the universe can greatly promote the development of modern science. The study of celestial bodies in the sun and solar system, including the earth and artificial satellites, has many applications in aerospace, geodesy, communication and navigation. "(Professor Huang Tianyi, Astronomy Department, Nanjing University)

Astronomy originated from ancient human acquisition of seasons and divination activities. It is a subject that mainly observes and explains the material conditions and events of celestial bodies. It mainly studies the distribution, movement, position, state, structure, composition, nature, origin and evolution of celestial bodies. In ancient times, astronomy was also closely related to the formulation of calendars. The difference between astronomy and other natural sciences is that the experimental method of astronomy is observation, through which all kinds of information of celestial bodies are collected. Therefore, the study of observation methods and means is a direction that astronomers strive to study.

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Since ancient times, humans have been very interested in stars and planets. Ancient astronomers only observed the sky with the naked eye. 1608, people invented the telescope. Since then, astronomers can observe stars and planets more clearly. Galileo, an Italian scientist, was one of the first people to study space with a telescope. Today, astronomers use many different types of telescopes to collect information about the universe. Some telescopes can collect weak light from distant celestial bodies, such as X-rays. Most telescopes are placed on the earth, but some telescopes are placed in space and run along the orbit, such as the Hubble Space Telescope. Now, astronomers can also learn some space information by launching space probes.

[history]

Ancient astronomers determined time, direction and calendar by observing the sun, the moon and other celestial bodies and phenomena. This is also the beginning of astrometry. If people observe celestial bodies and record astronomical phenomena, the history of astronomy will be at least five or six thousand years. Astronomy occupies a very important position in the early history of human civilization. The pyramids in Egypt and Stonehenge in Europe are famous prehistoric astronomical sites.

The research category of astronomy and the concept of astronomy have been developing continuously since ancient times. In ancient times, people could only observe celestial bodies with the naked eye. In the 2nd century AD, the geocentric theory put forward by Ptolemy, an ancient Greek astronomer, dominated the western understanding of the universe 1000 years. It was not until16th century that Copernicus, a Polish astronomer, put forward a new theory of cosmic system-Heliocentrism. 16 10, Italian astronomer Galileo made a refraction telescope independently, and for the first time he saw sunspots, the surface of the moon and the surfaces and profits and losses of some planets through the telescope. At the same time, Newton founded Newtonian mechanics, which produced a new branch of astronomy-celestial mechanics. With the birth of celestial mechanics, astronomy has entered a new stage from simply describing the geometric relationship and motion of celestial bodies to studying the interaction between celestial bodies and the causes of celestial motion, which is a great leap in the history of astronomy.

/kloc-The invention of astrophotography and spectroscopy in the mid-9th century enabled astronomers to further study the physical properties, chemical composition, motion state and evolution law of celestial bodies, thus further studying the nature of problems, thus resulting in a new branch of astrophysics. This is another leap in astronomy.

/kloc-radio telescopes began to be used in the 1950s. In the 1960' s, we made achievements called "four major discoveries in astronomy": microwave background radiation, pulsars, quasars and interstellar organic molecules. At the same time, humans have also broken through the shackles of the earth and can observe celestial bodies in the sky. Besides visible light, ultraviolet rays, infrared rays, radio waves, X rays and gamma rays of celestial bodies can also be observed. These have made great progress in space astronomy, and also had a great impact on the achievements of modern astronomy.

[Research object and field]

Astronomy studies various celestial bodies. The earth is also a celestial body, so the whole earth is also one of the research objects of astronomy. At first, the ancients determined the time, direction and calendar by observing the sun, moon and stars in the sky, and recorded the astronomical phenomena.

With the development of astronomy, the detection range of human beings has reached a distance of about 654.38+000 billion light years from the earth. According to the scale and scale, the research objects of astronomy can be divided into:

Planetary level:

Including planets in the planetary system, satellites orbiting planets and a large number of small celestial bodies, such as asteroids, comets, meteoroids and interplanetary matter. The solar system is the only planetary system that can be directly observed at present. But there are countless planetary systems like the solar system in the universe.

Star level:

Now people have observed hundreds of millions of stars, and the sun is just an ordinary one among countless stars.

Galaxy level:

The solar system where human beings live is just the corner of the Milky Way galaxy composed of countless stars. The Milky Way is just an ordinary galaxy. In addition to the Milky Way, there are many extragalactic galaxies. Galaxies have further formed larger celestial systems, such as galaxy clusters, galaxy clusters and supercluster.

The whole universe:

Some astronomers have proposed a total galaxy one level higher than the supercluster. According to the current understanding, the total galaxy is the universe that can be observed by human beings at present, with a radius of more than 65.438+0 billion light years.

One of the hottest and most unconvincing topics in astronomical research is the study of the origin and future of the universe. There are endless theories about the origin of the universe, among which the most representative, influential and supportive one is the Big Bang theory put forward by American scientist Gamov and others in 1948. According to this theory, the universe was born in a violent explosion about 654.38+03.7 billion years ago. Then the universe expands, the temperature drops, and all kinds of elementary particles are produced. With the further decline of temperature of the universe, matter began to collapse due to gravity, and gradually condensed. When the age of the universe was about 10 years, galaxies began to form and gradually evolved into what they are today.

[Research methods and means of astronomy]

The object of astronomical research is huge in scale, extremely long in time and extreme in physical characteristics, so it is difficult to simulate it in the ground laboratory. So the research methods of astronomy mainly rely on observation. Because the earth's atmosphere is opaque to ultraviolet rays, X rays and gamma rays, many methods and means of space exploration have appeared one after another, such as balloons, rockets, artificial satellites and spaceships.

Astronomical theory is often due to the lack of observation information, and astronomers often put forward many hypotheses to explain some astronomical phenomena. Then, according to the new observation results, the original theory is revised or replaced by a new theory. This is also where astronomy is different from many other natural sciences.

Astronomy and astrology

Astronomy should be separated from astrology. The latter is a pseudoscience that tries to predict a person's fate through the running state of celestial bodies. Although their origins are similar, they often mixed together in ancient times. However, there are obvious differences between contemporary astronomy and astrology: modern astronomy is a subject that uses scientific methods to study celestial bodies; Astrology corresponds the position of celestial bodies to people through comparison and association. Simply put, astrology focuses on predicting people's fate.

[potential customers]

Astronomy has entered a brand-new stage. Over the years, astronomical observation methods have been extended from traditional optical observation to all electromagnetic waves from radio, infrared and ultraviolet to X-rays and γ-rays. This leads to the discovery of a large number of new celestial bodies and phenomena, such as quasars, active galaxies, pulsars, microwave background radiation, interstellar molecules, X-ray binaries, γ -ray sources and so on. , making astronomical research unprecedentedly prosperous and active. The space telescope with a diameter of 2 meters has entered the orbit and started to work. A number of optical telescopes with the aperture of 10 meter will be built. Very long baseline interference array in radio and space very long baseline interferometer, extra-space telescope equipment in infrared and advanced X-ray astronomical equipment in X-ray will come out soon. The gamma-ray observatory has been put into operation. These instruments are powerful, far exceeding the existing astronomical equipment. It can be expected that the use of these astronomical instruments will inject new vitality into astronomy and raise people's understanding of the universe to a new level, and astronomy is on the eve of a great leap.

Ancient Egypt and astronomy

They made their own calendars. Marx said: "The need to calculate the fluctuation cycle of Nile water gave birth to astronomy in Egypt." In other words, the knowledge of astronomy comes from the observation of nature. The ancient Egyptians found that while the sun and Sirius rose on the horizon, the Nile also rose in the delta. They set the time between these two events as 365 days a year. Divide the whole year into 12 months, with 30 days each month and the remaining 5 days as festivals; At the same time, a year is divided into three seasons, namely "flood season", "grain growing season" and "harvest season", and each season lasts for four months. Herodotus said: "The Egyptians were the first human beings to put forward the method of timing the solar year ... In my opinion, their timing method was better than that of the Greeks, because the Greeks inserted a leap month every other year.

The Egyptians divided day and night into 12 parts, and each part was the time from sunrise to sunset or from sunset to sunrise112. The Egyptians used a stone bowl to calculate time. There is a small mouth at the bottom of the stone bowl, and water drops leak out of the bowl at a fixed speed. The stone bowl is engraved with various marks to indicate the time of different seasons. There is no doubt that astrology in ancient Egypt was very developed. Just like the characteristics of ancient Egyptian civilization, their twelve constellations are also represented by the gods of ancient Egypt.

The ancient Egyptians' study and knowledge accumulation of stars originated from the needs of ancient agricultural production. Agricultural production in ancient Egypt, due to

In the sowing season, the harvest of fields and orchards depends on the annual flood of the Nile, which is related to the movement of stars, especially every 1460 years, sunrise, Sirius and Nile flood occur at the same time. So monks began to make celestial maps very early. Astronomy in Egypt, like mathematics, is still in a low-level development stage, and still lags behind Babylon. In ancient Egyptian literature, there is no description of mathematical instruments, and there is no record of observing solar eclipse, lunar eclipse or other celestial phenomena. Egyptians used to regard planets as wandering celestial bodies, named them stars and constellations (rarely equated with modern ones). So their only creation can be exaggerated as the name of "astronomy". Some inscriptions preserved from the ancient kingdom to the late Ptolemaic era include a list of sky divisions. The so-called "Dekan" by the Greeks (Zodiac 10 degree division) is the so-called night 12 hours. People use dekan to divide the years. A year consists of 36 consecutive weeks, and the duration is 10 days. 36 Dekan * * * is 360 days, which constitutes one year. However, there are still five days missing, so every few years, Dekan's weekly appearance time has to be moved back. The Egyptian concept of the universe is often explained by different myths, and some paintings of different celestial bodies have also been preserved. In the pictures in the tombs of the New Kingdom era, we can see the goddess of the sky, Noot. Her body bends on the earth to form the dome of the Heavenly Palace, and her abdomen is the sky, decorated with the so-called "star belt". There are two solar boats along the belt, one of which is pulled by the sun god on its head. He travels in the sky by sun boat and sunset boat every day. The god of the atmosphere stood under the cow's stomach and raised his hands to support the cow's stomach, which is the sky. The limbs of longicorn are supported by two gods. According to another myth, Nut, the goddess of the sky, embraced Gabe, the god of the earth. Her father, Shu, the god of the atmosphere, supported the goddess with both hands and separated her from Gabe, leaving only Nut's feet and fingers in contact with the ground, while Gabe was lying on the ground half-way. These myths and legends reflect Egyptians' vague concepts of heaven, earth and stars. Some monks in Egypt were designated as "time recorders". They monitor the movement of the stars at night every day. They need to record the fixed sequence of stars, the movements of the moon and planets, the rising and falling times of the moon and the sun, and the orbits of various celestial bodies. These people also collate the above information and report the changes in celestial bodies and their activities. In the tombs of Ramses VI, VII and IX, the star division maps of different periods are preserved. It consists of 24 tables, one of which is used as an interval every half month. Each table is accompanied by a description of the constellation diagram. The astronomical map in Senemut's tomb under the rule of 18 dynasty can be said to be the earliest known astronomical map. A group of stars known to Tianpu astronomers is "Ikai Star", that is, "Stars that will never disappear". Obviously, it's Polaris. The second group is "Yi Kai Willidu", that is, "the never-ending star". In fact, it is a planet. Whether the Egyptians knew the difference between planets and stars has not been reported. The stars they know are Sirius, Orion, Ursa major, Cygnus, Cassiopeia, Draco, Scorpio and Aries Palace. The planets they noticed were Jupiter, Saturn, Mars and Venus. Of course, their understanding of stars is not accurate, and the relationship between stars and constellations is rarely equated with modern knowledge. Sun worship occupies an important position in Egypt. Since the pre-dynastic era, the sun has been portrayed as a scarab, which occupies a prominent position in Egyptian religion. Moreover, the sun in different periods has different names. There are other sun gods in different regions and times. The Egyptian civil calendar is divided into 12 months, with 30 days in each month and 360 days in a year, and then five days are added to make 365 days a year. However, in fact this calendar is not accurate. Because the astronomical year of. 1 is 365.25 days, the Egyptian civil calendar lags behind the astronomical calendar of 1 day every four years. However, in ancient times, this was the best calendar. The julian calendar in Rome was formulated by Julius J. Caesar by adding leap years to the solar calendar in ancient Egypt. In the Middle Ages, Pope Gregory reformed julian calendar and became the universal Gregorian calendar. In this respect, we can also see the great contribution of the ancient Egyptians.

Astronomy is a natural science that studies the structure and development of celestial bodies and the universe, including the structure, nature and operation law of celestial bodies.

Born between heaven and earth, human beings began to explore the mysteries of the universe from a very early age, so astronomy is the oldest science, which is closely related to human labor and survival from the beginning. It is six basic disciplines with mathematics, physics, chemistry, biology and earth science.

The study of astronomy is of great practical significance to our lives, such as timing, making calendars, and determining directions. The development of astronomy has had a great influence on human's view of nature. Heliocentrism of Copernicus once liberated natural science from theology; Kant and Laplace's theory about the origin of the solar system opened the first gap in the metaphysical view of nature in the18th century.

An important subject in astronomy is the origin and evolution of various celestial bodies. The main research method of astronomy is observation, and constantly creating and improving observation means has become a subject that astronomers make unremitting efforts to. Astronomy, like other disciplines, always draws on and permeates many neighboring sciences. Every development of astronomical observation means has brought useful things to applied science.

Astronomy follows the development path of observation-theory-observation, and constantly extends people's horizons to new depths in the universe.