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Astronomical observation

Observing the activities of celestial bodies

Astronomical observation is observation celestial bodies Of activity , originated in 1608, and the important means is astronomical telescope.

Chinese name: Astronomical observation
Important means: Astronomical telescope

Meaning: Pushing human beings to universe Understanding.
Origin: 1608
Improvements: Germany astronomer Kepler

catalog

Introduction to observation

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It is no exaggeration to say that without the birth and development of telescopes, there would be no modern astronomy. With the continuous improvement and enhancement of telescope performance in all aspects, astronomy is also experiencing a huge leap, rapidly promoting human universe Understanding.

Astronomical observation

astronomy It is an ancient and ever new natural science, and its research object is the laws of the universe. 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. Astronomy differs from other natural sciences in that the main experimental method of astronomy is observation, through which various information about celestial bodies is collected. Therefore, the study of observation methods and means is a direction that astronomers strive to study. Constantly improving and broadening the methods of astronomical observation is the endless pursuit and mission of astronomers and astronomers, and also promotes astronomy The driving force and source of development.

Historical origin

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In 1608, Netherlands Glasses dealer Li Bolsai accidentally found two pieces Lens Can see the distant scenery, inspired by this, made the first telescope in human history. In 1609, astronomer Galileo We made a frame with a diameter of 4.2 cm and a length of about 1.2 meters Refracting telescope 。 This telescope brings astronomy telescope Times.

Then in 1611, Germany astronomer Kepler The astronomical telescope has also been improved to increase the magnification. Until today, people still use these two kinds of refracting telescopes. The telescope is Kepler type. Refracting telescope Its advantages are long focal length, large scale of negative film, insensitive to lens tube bending, and suitable for astrometry. But it also has some defects, huge optical glass Casting was also very difficult. By 1897, the development of refracting telescopes had reached its peak. Technical limitations made it impossible for larger refracting telescopes to appear in the next 100 years.

The first one was born in 1668 Reflecting telescope 。 After several failures in grinding aspherical lens, Newton Another idea was invented Reflecting telescope 。 It is a great success to replace refractors with reflectors. It has many advantages and is relatively easy to make compared with the refracting telescope, although it also has inherent shortcomings.

Catadioptric telescope It first appeared in 1814. In 1931, Germany Photologist Schmidt matched an aspherical thin lens close to a parallel plate with a spherical reflector to make a Catadioptric telescope 。 This kind of telescope has strong light power, large field of view and small aberration, and is suitable for taking pictures of large areas of the sky, especially for weak nebulae. Such telescopes have become important tools for astronomical observation. It takes into account the advantages of both refraction and reflection telescopes, and is very suitable for amateur astronomical observation and photography.

For more than three hundred years, Optical telescope It has always been the most important tool for astronomical observation. In 1932, Jansky. K. G used Radio antenna The detection of radio radiation from the center of the Milky Way Galaxy (in the direction of Sagittarius) marks the first window for human observation beyond the traditional optical band. After World War II, Radio astronomy talent showing itself. radio telescope It plays a key role in the development of radio astronomy. Four major discoveries of astronomy in the 1960s: quasars, pulsars Interstellar molecule And cosmic microwave background radiation are observed with radio telescopes.

selection of the site

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It is absolutely impossible to make astronomical observations without a good site. The environment around the observation site directly affects the observation effect: if there are too many obstacles, it is difficult to see the observation target, let alone the observation; If the airflow changes too much, the image will shake and deform, which will reduce the resolution of the telescope; If the sky is very bright by the light, the extreme magnitude (the magnitude of the darkest star visible to the naked eye) will be reduced, in other words, the magnitude of the visible star fixed star The number will decrease, which will have a great impact on observation and photography, or even cannot be carried out at all... In order to achieve the desired effect of observation activities, it is necessary to select a suitable site, and the following points should be paid attention to when selecting:

Open field

Select an open area, such as a sports ground, to maximize the visible sky area. If you live in a residential area with many tall buildings, it is absolutely impossible to observe anywhere downstairs. It is conceivable that it is very difficult to see the part beyond the ceiling between several buildings. These troubles can be avoided in places like sports fields.

Air flow influence

Pay attention to the influence of air flow. If you observe near buildings, you should pay special attention to avoiding open windows, because it is easy to generate complex air flow near open windows, which will affect the observation effect. In addition, it should be avoided to observe directly on the cement ground as far as possible. Because the specific heat capacity of cement (how much heat is released to reduce the same temperature) is very small, the temperature will drop quickly at night, which will also cause changes in air flow. Land is much better than cement ground. If conditions permit, it is better to observe on the grassland. Because the grassland contains a lot of water and the specific heat capacity of water is large, it is not easy to cause dramatic changes in air flow. Currently, many observatory They are all built on the seashore or island, mainly for this reason.

Light influence

With the development of economy, there are more and more lights in the city, and the sky is brighter and brighter, and many lights are left on all night. As mentioned above, this has had a very serious impact on astronomical observation. Although you can't prevent urban development for observation, we can take the initiative to avoid lights. In the United States, in order to avoid the influence of light, it is not uncommon for astronomers to drive dozens or even hundreds of kilometers to the wild for observation by themselves - we can only learn from them and find a place that we think is dark enough - of course, it should be a place that we are familiar with, and we should never go to the wilderness without our knowledge to avoid danger.

Observation site

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If there are no mountains, there is no place in the city suitable for doing deep space Because of atmospheric pollution and light pollution It's too serious. It is estimated that only the sun can be observed in cities/ moon /Jupiter/Saturn and Venus. Observing Mars is relatively reluctant.

Detection means

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In addition to radio observations, non visible astronomical observations also include Infrared observation 、 Ultraviolet observation 、 X-ray Observation and gamma ray observation, etc. Because these astronomical observations are more affected by the earth's atmosphere, people often install telescopes on aircraft or use hot air balls to carry them high in the sky. Later rocket 、 space shuttle Space technologies such as satellites and satellites send telescopes out of the Earth's atmosphere.

Compared with ground observation equipment, space observation equipment has great advantages. optics Space telescope It can receive much wider wave band than on the ground. Since there is no atmospheric jitter, resolving power It has also been greatly improved. There is no gravity in space, and the instrument will not deform due to its own weight.

Named after the astronomer Hubble Hubble Space Telescope (HST) is created by NASA The first of the four giant space observatories that he presided over was also the largest, most invested and most noticed astronomical observation project of all. It was built in 1978, took seven years to design, completed in 1989, and launched by the space shuttle on April 25, 1990, costing 3 billion dollars. However, the spherical aberration of the primary mirror optical system caused by human factors had to be repaired on a large scale on December 2, 1993. The successful repair makes the performance of the Hubble telescope reach or even exceed the original design goal. The observation results show that its resolution is dozens of times higher than that of large telescopes on the ground. It has a very important impact on the development of the international astronomical community.

Function introduction

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Space astronomy observation spacecraft is a space tool that sends observation instruments to the space hundreds of kilometers above the ground for astronomical observation. Space astronomical observation is also called extraatmospheric observation. Although people began to use the satellite aircraft , Balloon rocket Detect. But they have great limitations. The flight altitude of the aircraft is about 10~25km, which improves the infrared observation, but it is still powerless to receive high-energy shortwave radiation. Although the flight height of the balloon is higher than that of the aircraft, the atmosphere above the balloon still has an impact on astronomical observation. Rocket has the weakness of short observation time. Astronomical observation by spacecraft has the advantages of high altitude and long observation time. The altitude of the spacecraft is generally more than several hundred kilometers, which can avoid the earth's atmosphere and geomagnetic field Impact. The working life of spacecraft is usually several months to several years. Space astronomy observation by spacecraft can not only observe celestial bodies Electromagnetic radiation of all wavelengths, and particle radiation of different energies can also be observed. For stars, the observation wavelength is only limited by interstellar gas absorption; for the moon, planets and Interplanetary space , direct sampling or approximate observation can be made.

A complete space astronomical exploration system consists of spacecraft, launch vehicle and ground support equipment. Spacecraft is the main part of carrying scientific instruments and carrying out exploration tasks. Spacecraft for space astronomical observation must have the ability to control their own attitude changes and accurate orientation accuracy to complete the task of identifying celestial bodies, determining the spatial distribution of radiation and the location of radiation sources. In order to conduct complex scientific investigations, spacecraft must also have the ability to store and transmit large-scale data quickly. Countries all over the world have launched a large number of spacecraft. In order to carry out various specific missions, a series of research satellites, planets and interplanetary spacecraft have also been launched to form different observation series.

Shopping Guide

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Shopping Guide

For astronomical observation, the aperture (object lens diameter) of telescope for astronomical observation is the most important due to the weak light of celestial bodies. The larger the aperture, the larger the luminous flux, and the larger the cost and volume. The names of astronomical telescopes in the world are also based on the caliber, such as 120 cm, 2.16 m (the largest in China), and 6 m (the former Soviet Union and the largest in the world). Therefore, if the economic conditions permit, the telescope for astronomical observation should first try to choose the one with large aperture.

Multiple=objective lens focal length/eyepiece focal length, so when grinding lenses, as long as the objective lens focal length is increased or the eyepiece focal length is reduced, a higher magnification can be obtained. If you want, the multiple can easily be hundreds of thousands of times, but in fact, the reasonable use multiple of a telescope is subject to objective lense The aperture and observation environment limit: the multiple of large aperture can be higher, but it is also limited, that is, the maximum multiple of large astronomical telescopes used by the observatory is usually only a few hundred times, because the observation environment has a greater impact on the telescope. With the increase of the exponent, the dust and air flow in the atmosphere will also be magnified at the same time. At the same time, the higher the multiple, the smaller and darker the observation field of view Resolution It will reduce the observation effect, which is why it costs a lot of money to place in space hubble space telescope Reason for. In addition, the high magnification also requires high stability of the telescope. When it is tens of times, a small touch will also make the scene of the telescope shake. When it is hundreds of times, even a light breeze will cause the scene to shake constantly, making it difficult to observe normally. Another big disadvantage of the smaller field of view caused by high magnification is that it is extremely difficult to find the target. Friends who have used astronomical telescopes have this experience: they want to use high-power binoculars It is troublesome to find a target. After it is easy to find the target to be observed, the target will soon leave the field of view due to the rotation of the earth and have to find again. Therefore, it is impractical to say that the blind pursuit of high magnification is unrealistic. According to optical laws and long-term experience, the maximum practical magnification of a telescope is about D (D=objective aperture, mm). If the aperture of a telescope is 50mm, the maximum practical magnification should not exceed 50 times.

In astronomical observation, in addition to the moon, the sun, several planets, star clusters Nebula 、 Galaxy Such celestial bodies can observe the view plane because they are relatively close to or larger than the earth. For all other stars, because they are too far away from the earth, even the evolution theory of Hubble telescope in space can only see a bright spot many times. However, the larger the aperture, the more bright stars will be seen, so it is the same for astronomical telescopes Binoculars Similarly, the aperture is more important than the magnification. Since astronomical observations are fixed on the tripod, the larger size is irrelevant.

Commonly seen in Russia, suitable for astronomical observation Monocular telescope There are 20x50 pirate type, 20-30x50 small table type, 30-60x70 large table type, 55x105 reflective type, 111x116 reflective type, etc. These monocular telescopes are all exported by Russian military factory. Both the appearance and technology, as well as the optical quality are very good, and the multiple design is also very reasonable, all of which are within the D value. In addition, full image conversion devices are used, and the view from the mirror is consistent with the actual direction of the scene, It is not only suitable for astronomical observation, but also suitable for ground observation.

Monocular mirror

Chinese astronomy enthusiasts usually buy a single telescope for astronomical observation. In fact, most foreign astronomy enthusiasts generally use large aperture binoculars, which is very reasonable: the biggest advantage of binoculars is that they can observe with both eyes at the same time, which not only has a wide field of view, but also is more comfortable, not easy to fatigue, and has a strong sense of three-dimensional, In particular, the effective pupil diameter of the human eye has been fully utilized, which has greatly improved the observation sensitivity. Its actual observation effect is far higher than that of a single telescope with the same aperture. For example, a binocular with an aperture of 50 mm is about as bright as a single telescope with an aperture of 70 mm. It can be seen that it is more economical and practical to use binoculars for astronomical observation. Many amateur astronomers abroad have made many astronomical discoveries with large aperture binoculars, such as the famous Baiwu comet It was first discovered by Japanese astronomer Yuji Baiwu with a Fuji 25x150 large aperture binoculars. Of course, most foreign astronomer enthusiasts have economic strength, such as the Fuji 25x150 large aperture binoculars that they use most, which cost about 60000 yuan to 70000 yuan. In addition, the 25-40x100 large binoculars produced by China 98 Factory for remote observation of military posts are excellent for astronomical observation and relatively inexpensive. Readers with economic ability can consider purchasing them.

Lunar observation

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For the vast number of astronomy enthusiasts and universal astronomy educators, mastering the optical observation of the moon is really the foundation of a skill. Because the moon has a large viewing surface, clear and recognizable surface, many observable items, and observation results can be easily obtained through careful observation, moon observation is the most vivid and real activity for universal astronomy education.

Overall structure

There are 19 different structures on the front of the moon Moon Sea so Each month has its own characteristics. There are fifteen famous mountains stretching, with huge peaks and towering cliffs. Circular hills are everywhere.

Lunar phase change

From crescent moon to bright moon, it has always been favored by astronomy lovers. Opposite lunar surface Light dark boundary Regional observation is interesting. In a year, each area on the lunar surface is swept 25 times by the light and dark boundary, which means 25 times of sunlight from different angles.

Local area

For example, the observation of the rain sea environment Kexi Cliff Observation of Copernicus Crater Tycho Crater Aristak Crater , as well as the observation of their radiation patterns.

Libration

because Lunar libration The influence of the moon in the north-south direction (i.e. up and down direction) is ± 6 The change of 7 is like looking up and nodding. There is ± 7 in the east-west direction (i.e. left and right) The change of 6 seems to be a swing dance. Therefore, we see 59% of the entire lunar surface from Earth. Long term visual observation will give you a feeling. Long term photographic observation can give you such wonderful pictures of the moon.

Diameter change

Because the moon's orbit is elliptical. Its distance from the earth is always changing, and the apparent diameter of the moon when viewed from the earth also varies between 29'22 - 33'26 -. It can't be felt by the naked eye, but it can be clearly reflected from the comparison of the photos of the moon's perigee and apogee. If your telescope objective focal length If it is 1000 mm, then the diameter of the lunar image varies from 8.4 mm to 9.6 mm.

development history

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Satellite series

At present, astronomical satellites are the most widely used space astronomical observers. According to different observation objects and tasks, astronomical satellites can be divided into solar observation satellites and non solar exploration astronomical satellites. Some satellites have both solar observation and non solar detection capabilities.

Solar observation

To observe the sun from space, we mainly use the earth orbit sun observation satellites Deep space detector And Skylab Apollo telescope mount 。 In addition, many geophysical exploration satellites, such as Orbital geophysical station (OGO) series, there are also solar observation experiment projects. In the early 1960s, the United States began to launch two solar observation satellite series that continued throughout the solar cycle Solar radiation monitoring satellite (SOLRaD) Orbital Solar Observatory (OSO) series. The solar observation satellites of the Soviet Union are mainly included in the "Forecast" series, except for some satellites in the "Cosmos" series and some satellites in the "International Cosmos" series jointly developed by the Soviet Union and Eastern European countries. "Forecast number" and interplanetary monitoring platform (IMP) series are respectively used by the Soviet Union and the United States to study the solar terrestrial relationship, investigate the solar wind, interplanetary magnetic field, the magnetosphere and Interplanetary matter Interplanetary monitoring station with equal characteristics. In addition, the European Space Agency has successively launched the International Radiation Research (IRIS) satellite to study the sun and radiation, and the "Ted" - 1A (TD-1A) satellite, which is mainly used for non solar exploration and supplemented by solar observation, and launched the "International Solar Earth Relations Explorer" (ISEE) in cooperation with the United States. West Germany and the United States jointly launched the Helios satellite. Helios reached about 0.3 AU away from the sun and entered the heliocentric orbit. It is currently the closest deep space solar observer to the sun. Skylab is a multi-purpose experimental manned orbital space station, which carries Apollo? Key? High resolution TV and photographic observations of the sun are carried out at such wave bands as Woop ultraviolet and X-ray.

Non solar detection

Non solar exploration astronomical satellites inspect the sky radiation source in a certain band or several bands, measure its direction, intensity and radiation spectrum characteristics, and observe galactic and extragalactic objects. Non solar exploration satellites in the United States mainly include Orbital Observatory (OAO), Radio Astronomical Explorer (RAE), Small Astronomical Satellite (SAS) and High Energy Astronomical Observatory (HEAO). Other countries and organizations have also launched some non solar astronomical satellites, including the European Space Agency's "Ted" - 1A (TD-1A) satellite, the Cosmic Ray Observation Satellite-B (COS-B), the Netherlands Astronomical Satellite (ANS) jointly launched by the Netherlands and the United States, the United Kingdom's "Ariel-5" satellite, and the French ultraviolet celestial analysis satellite (AURA) , the French Soviet "Signe-3" satellite, the Soviet "Cosmos" 215 satellite, etc.

The lunar, planetary and interplanetary probe series spacecraft can become detectors for direct sampling or approaching observation of the moon, planets, other celestial bodies in the solar system and interplanetary space after flying out of the earth.

Sheshan Astronomical Observatory

Lunar probe

Astronomical observation

Since 1959, when the Soviet Union launched the first lunar rocket to the moon - "Moon" 1, some countries have launched various lunar probes in different ways (approaching flight or hard landing, orbit circling, soft landing, sample retrieval, manned lunar landing flight, etc.) Through photographing, automatic measurement, sampling analysis and field investigation, the moon and its nearby space were investigated in detail. The United States has launched "Wanderers"“ Lunar Orbiter ”, "Lunar Surveyor" and "Apollo". "Wanderers" 7~9 successfully completed the task. Five lunar orbiters 3, 5 and 6 respectively achieved soft landing on the moon. Apollo lunar exploration is the largest lunar exploration project in the United States. The Soviet Union's lunar exploration program is mainly the "Luna" series. "Luna" 1~3 is the primary stage, which aims to fly to the moon to achieve hard landing; "Luna" 4~14 is the intermediate stage, which tests the soft landing technology on the moon, flies around the moon to investigate the lunar space, and studies the lunar soil; "Luna" 15 is the advanced stage, which develops into an automatic science station on the moon. Luna 16 realized unmanned automatic excavation of lunar rock samples and returned to the Earth. "Luna" 17 and "Luna" 21 will each carry a lunar rover. After soft landing, the lunar rover will be operated by the ground station and will automatically travel on the lunar surface for investigation.

Interplanetary probe

Planetary and interplanetary probes: The launched planetary and interplanetary probes include American "Pioneer", "Sailor", "Pirate", "Traveler" and Soviet "Venus", "Mars" and "Probe".

Astronomical observation

They flew to Venus, Mars, Mercury, Jupiter and Saturn By approaching flight or soft landing on the surface of the planet, we can study the surface of the planet, the atmosphere of the planet and the interplanetary matter between the Earth and these planets through photography and automatic measurement. In addition, the interplanetary space around the Earth has been measured by the Interplanetary Monitoring Station and the "Forecast" series. For the flight to more distant outer planets, because the flight time is long and the spacecraft is farther and farther away from the sun, it is impossible to use solar energy for power supply, so special spacecraft must be designed.

Manned orbital space station

Kyroka Astronomical Observation Tower

With the development of space technology, Skylab, an experimental manned orbital space station, has been launched. It can carry out a wide range of scientific experiments and applied research. In addition to biomedicine, earth resource exploration and comprehensive experiments, it also undertakes the task of space astronomical observation. The future orbital space station will use the space shuttle to transport personnel and instruments and equipment to the space station for maintenance.

matters needing attention

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The effect of astronomical observation is greatly affected by external factors, so there are many points that need attention in the observation process, which are summarized as follows.

lighting

When you find an ideal enough observation site to avoid the interference of city lights, you must be very excited. But remember the following points to avoid unnecessary trouble.

Lijiang Gaomeigu Astronomical Observatory

You should know that it takes at least half an hour for a normal person to fully adapt to the darkness, so that pupil When stretched to the maximum, the luminous flux of the human eye will be increased to reach the best state. If you look at bright objects (such as lights, fire and even the moon) intentionally or unintentionally during the adaptation process, your pupils will shrink suddenly, which will make the previous adaptation process useless. You have to spend another half an hour to adapt to the darkness, wasting valuable observation time. Therefore, in the process of adaptation and observation, the stimulation of strong light on eyes should be absolutely avoided.

1. Lighting

Brighter lamps such as incandescent lamps and energy-saving lamps used at ordinary times can never be used in observation. In the dark, red light is the least irritating to the human eye. Therefore, a piece of red cloth or red plastic cloth with appropriate thickness can be used to cover the flashlight with low power for short-term lighting.

2. Flash lamp

Sheshan Astronomical Observatory

In the process of observation and adaptation, flash lights should never be used. The brightness of the flash is extremely strong. Although the luminous time is only a few tenths of a second, it can also make your adaptation more than half an hour in vain and affect the observation. If people around you take astronomical photography, your flash may make others' hard work in one night be wasted. If it is necessary to take photos, they should be taken when all observations are completed and there are no observers within a few tens of meters around.

warm oneself

It is often cold to observe the weather in winter. If you need heating, you must not make a fire, especially near the telescope. The heat released from combustion will make the air shake violently, causing the celestial bodies to be blurred, and the influence range is large. Moreover, the bright firelight also has great stimulation to the human eye. In the same principle, high-power electric heaters cannot be used, which not only has poor effect, but also wastes a lot of electric energy. The best way is to put on more clothes and take blankets. If it's too cold, it's better to go home as soon as possible. After all, the body is the most important.

Mosquito prevention

There are many mosquitoes in the suburbs at night in summer. If you don't pay attention, you will be stung in half an hour. After all, the wild is different from home. Some methods that work well at home will lose their effect in the wild. For example, when burning mosquito repellent incense, because the outdoor air flow rate is fast, the mosquito repellent substances released by burning mosquito repellent incense will spread quickly and cannot achieve the desired effect. The most effective and convenient way is to wear long clothes and trousers. Although it may be hot, it is better than the taste of being stung by mosquitoes. In addition, a proper amount of toilet water and other drugs should be sprayed on the face and hands to ensure that there is no opportunity for mosquitoes.

Related books

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The latest astronomical observation manual (refined)

Latest Astronomical Observation Manual

Market price: 39.80 Author: Anton Van Pulu | Translator: Liu Yong

Translator: Anton? Fan Pulu | Translator: Liu Yong

press: Heilongjiang Science and Technology Press

Publication date: November 1, 2008 0:00

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