The second grade knows little about the universe.

1. Astronomical knowledge that the second grade of primary school should know.

Some celestial bodies in black holes are so massive that their gravity is so strong that nothing can escape from them, even light.

Without light returning, the eyes can't see the object, so it is called a "black hole". People on the earth of the zodiac look at the apparent path of the sun among the stars in a year, that is, the great circle where the earth's orbital plane intersects the celestial sphere forms an angle of 23 degrees and 26 minutes with the celestial equator, and intersects with vernal equinox and vernal equinox.

The two points on the celestial sphere of the yellow pole are 90 degrees away from the ecliptic angle, and those close to the north celestial pole are called "North Yellow Pole". The angular distance between the ecliptic pole and the celestial pole is equal to the ecliptic angle.

The North Yellow Pole is located at the center of the connecting line between Tianlong and the two stars. Zodiac: A strip on the celestial sphere with 8 degrees (* * * width 16 degrees) on each side of the ecliptic.

The orbits of the sun, the moon and the main planets are all on the ecliptic. To show the position of the sun on the ecliptic.

Divide the zodiac into twelve segments, which is called "Zodiac". From the vernal equinox, they are Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpio, Sagittarius, Capricorn, Aquarius and Pisces.

In the past, the zodiac and the zodiac were the same. With the vernal equinox moving westward, the vernal equinox in Aries has moved to Pisces two thousand years ago, and its name is no longer consistent with the constellation.

The three walls include Ziwei Garden, Taiwei Garden and Tianshi Garden. Purple element includes the sky area near the north celestial pole, which is roughly equivalent to the area of arch star; Taiwei Courtyard contains some constellations such as Maiden, Houfa and Lion. Tianshi source includes snake man, five immortals, giant snake, skyhawk and other constellations.

Twenty-eight lodgings are divided into seven lodgings in the east, seven lodgings in the west, seven lodgings in the south and seven lodgings in the north. Twenty-eight hotels are also called twenty-eight stars or twenty-eight houses.

At first, the ancients chose 28 stars to compare the movements of the sun, the moon, gold, wood, water, fire and earth as observation marks. The meaning of "lodge" is similar to the "palace" of the zodiac, indicating the position of the sun, moon and five stars.

In the Tang Dynasty, Twenty-eight Hostels became the main body of the twenty-eight celestial bodies, and these celestial bodies were still named after Twenty-eight Hostels. Different from Sanyuan, as a celestial body, Twenty-eight Hostels are mainly used to divide the ownership of star officials. The 28 huts start from Kakuk and are arranged from west to east, in the same direction as the sun and the moon.

East seven houses, namely Jiao, Kang, Emperor, Fang, Xin, Wei and Yi; North Seven Nights: Dou, Niu (Petunia), Female (bearded female), Virtual, Dangerous, House (Barracks), Wall (East Wall), West Seven Nights: Kui, Lou, Wei, Chang, Bi, Gou, Shennan Seven Nights Well (Cave Well), Ghost (Yugui) and Willow. In addition, there are some star officials who are closely related to these star officials, such as tomb, detached palace, ear, chop, graupel, corpse accumulation, right jurisdiction, left jurisdiction, Changsha, shrine and so on. , belonging to room, danger, room, completion and participation respectively.

In the Tang Dynasty, there were 183 stars in 28 places, including auxiliary officials or auxiliary stars. Cosmic velocity refers to the initial velocity necessary for launching artificial celestial bodies from the earth into the universe.

The first cosmic speed People call the speed of 7.9 kilometers per second "the first cosmic speed", which is also called "circumpolar speed". Below this speed, the object will return to earth under the action of gravity. Second cosmic speed If we increase the speed to 1 1.2 km/s, this artificial satellite can travel to the interplanetary space of the solar system without being affected by the gravity of the earth.

People call the speed of 1 1.2km/s the "second cosmic speed" third cosmic velocity. If the satellite is to fly out of the solar system and go to other planets, the speed must be increased to 16.7km/s, which is the so-called "third cosmic velocity". Because the number of days in the tropic year is not an integer, the number of days in a year is different from that in a leap year, some are 365 days and some are 366 days.

A year with 366 days is called leap year, and a year with 365 days is called average year. February in leap year is longer than average 1 day, and so are other months.

Generally speaking, a year divisible by 4 is a leap year. If the year is an integer of 100, the year divisible by 400 is a leap year. The lunar calendar of leap month and the solar calendar contain different days in a year, about 365 days in the solar calendar and 354 days in the lunar calendar.

In order to make the number of days in a year the same, one month is added in some years of the lunar calendar, and the added month is called "leap month". Because the Gregorian calendar year is only about 1 1 day older than the lunar calendar, it is impossible to add leap months every year. About 19 has seven leap months.

The time for the earth to orbit the sun once in the tropic year is called tropic year. The tropical year is 365 days, 5 hours, 48 minutes and 46 seconds (365,438+09 days). Astronomical science tips 1. Stars are the most basic celestial bodies in the universe, which can emit light by themselves and are composed of hot gas, mainly hydrogen and helium.

2. The sun is a spherical celestial body composed of hot gas, and its main components are hydrogen and helium. The volume of the sun is about 6.5438+0.3 million times that of the earth.

The atmospheric structure of the sun is the external structure of the sun, which is divided into photosphere, chromosphere and corona layer from inside to outside. The period of solar activity is 1 1 year, and the main signs are sunspots and flares.

The influence of solar activity on the earth: (1) disturbing the ionosphere of the earth's atmosphere; (2) the phenomenon of "magnetic storm" occurred; (3) produce aurora. 3. Planets are nearly spherical celestial bodies orbiting the sun in elliptical orbits. They don't shine, and their mass is much smaller than that of the sun.

The eight known planets in the solar system are: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. 4. solar eclipse when the sun, the moon and the earth run in a straight line, the shadow of the moon passes over the earth, which will cause an solar eclipse.

According to the degree that the sun is blocked by the moon, it can be divided into partial eclipse, total eclipse and annular eclipse. 5, eclipse When the sun, the earth and the moon run in a straight line, the moon runs into the shadow of the earth, it will form an eclipse.

According to the direct sunlight from the earth to the moon, it can be divided into partial solar eclipse and total solar eclipse.

2. Know little about the universe

The universe is a unity composed of space, time, matter and energy.

It is the synthesis of all space and time. Generally speaking, the universe refers to a space-time continuous system in which we exist, including all the matter, energy and events in it.

According to the Big Bang model, the universe is about 20 billion years old. Among the celestial bodies in the solar system, the surface temperature of Mercury and Venus is about 700K, and the surface of Venus is covered with dense carbon dioxide atmosphere and sulfuric acid cloud, and the air pressure is about 50 atmospheres, but the surface atmosphere of Mercury and Mars is extremely thin, and the atmospheric pressure of Mercury is even less than 2* 10-9 mbar; Earth-like planets (Mercury, Venus and Mars) all have a solid surface, while wood-like planets are fluid planets. The average density of Saturn is 0.70g/cm3, which is smaller than that of water. The average density of Jupiter, Uranus and Neptune is slightly higher than that of water, while the density of Mercury, Venus and Earth is more than five times that of water. Most planets rotate in the forward direction, while Venus rotates in the reverse direction. The surface of the earth is full of vitality, while other planets are an empty and desolate world.

The sun is a common and typical star in the star world. It is found that some red giant stars are thousands of times the diameter of the sun.

Neutron stars are only tens of thousands of times the diameter of the sun; The luminosity of Supergiant star is as high as several million times that of the sun, while the luminosity of white dwarfs is less than several hundred thousand times that of the sun. The density of red Supergiant star is as small as one millionth of that of water, while the density of white dwarfs and neutron stars can be as high as10000000 times and10000000000 times of that of water, respectively.

The surface temperature of the sun is about 6000 K, that of the O star is 30000K, and that of the infrared star is only about 600 K. The average magnetic field strength of the sun is 1* 10-4 Tesla, and the magnetic fields of some magnetic white dwarfs are usually thousands or tens of thousands of gauss (1 gauss =/kloc-0.

Some stars are basically constant in luminosity, while others are constantly changing, which is called variable stars. Some variable stars have periodic photometric changes, ranging from 1 hour to hundreds of days.

The luminosity of some variable stars changes suddenly, among which the most drastic changes are nova and supernova, and their luminosity can be increased by tens of thousands or even hundreds of millions of times in a few days. Stars tend to cluster into binary stars or clusters, which may account for 1/3 of the total number of stars.

There are dozens, hundreds or even hundreds of thousands of star clusters. Cosmic matter not only forms stars and planets in dense form, but also forms interstellar matter in dispersed form.

Interstellar matter includes interstellar gas and dust, with an average of only one atom per cubic centimeter, forming nebulae of various shapes in highly dense places. In addition to the stars and nebulae that emit visible light, there are also ultraviolet objects, infrared objects, X-ray sources, gamma-ray sources and radio sources in the universe.

Galaxies can be divided into elliptical galaxies, spiral galaxies, rod-shaped spiral galaxies, lens galaxies and irregular galaxies. In the 1960s, many extragalactic objects were discovered, which are experiencing explosions or throwing out huge amounts of matter, and they are collectively called active galaxies, including various radio galaxies, Seifert galaxies, N-type galaxies, Makarian galaxies, BL-type celestial bodies in Boetes, quasars and so on.

Many galactic nuclei have large-scale activities: airflow with a speed of several Qian Qian meters per second, energy output with a total energy of 65,438+0,055 Joules, mass and particle ejection, intense light changes and so on. There are various extreme physical states in the universe: ultra-high temperature, ultra-high pressure, ultra-high density, ultra-vacuum, ultra-high magnetic field, ultra-high speed motion, ultra-high speed rotation, ultra-large-scale space-time, superfluidity, superconductivity and so on.

It provides an ideal experimental environment for us to understand the objective material world.

3. Universal common sense

In natural science, astronomy is a basic subject to study the movement, structure, origin and evolution of various celestial bodies in the cosmic environment outside the earth. Its history can be traced back to the embryonic period of human civilization. In ancient times, nomadic people needed to identify the direction when they migrated by aquatic plants, and agricultural people needed to determine the season when they planted seeds on time. In the long-term practice year after year, they gradually discovered the close relationship between these major events affecting their lives and astronomical phenomena such as the sun, the moon and the stars. Babylonian clay tablets, Egyptian pyramids and Oracle Bone Inscriptions in China Yin Ruins all left rich examples of the birth of astronomy. Astronomy has always made great contributions to the progress of human civilization. /kloc-Heliocentrism of Copernicus liberated natural science from the shackles of medieval theology for the first time in the 6th century. The classical mechanical system established by Galileo and Newton in the17th century to study the laws of motion of celestial bodies in the solar system is still the basis of modern engineering science (including aerospace science). The research on the internal structure and energy of the sun and stars in the 1930s produced the concept of thermonuclear fusion, which provided enlightenment for human beings to use nuclear energy. Especially in the past half century, human's enthusiasm for exploring the universe, on the one hand, has strongly promoted the development of a series of high and new technologies such as telemetry and telecontrol, space technology and computing technology, and directly served the national economic departments such as global communication, resource investigation and weather forecast. The application of these technologies in astronomy has made people's understanding of the universe advance by leaps and bounds. For the first time, it can be explained from the unified principle, from elementary particles to chemical elements, from galaxies to stars, from the sun to the earth, from protozoa to humans, it is tens of billions.

The earth where we live is an ordinary member of the solar system. The central celestial body of the solar system is the sun, which is a gas ball with a radius of about 700,000 kilometers and a surface temperature of 6000K K. Its core temperature is as high as1.5,000 K, and a nuclear reaction of hydrogen fusion into helium occurs. The light and heat on which we live are produced by this nuclear reaction. There are nine planets in the solar system, namely Mercury, Venus, Earth, Mars, Jupiter, Uranus, Neptune and Pluto. The outermost Pluto is about 6 billion kilometers away from the sun. There are thousands of asteroids running between Mars and Jupiter. There are comets and meteors in the solar system.

There is a band of light across the sky in the clear night sky, which is called the Milky Way. In fact, it is a huge celestial system composed of stars and diffuse matter, called the Milky Way. The luminous part of the Milky Way is about 70,000 light years in diameter and 20,000 light years in maximum thickness, like a rotating discus with a flat protrusion in the center. The sun is an ordinary star in the Milky Way. There are about 200 billion stars in the Milky Way, which are far apart from each other. Proxima centauri, which is closest to the sun, is also 4.3 light years away, which is 60 million times the radius of the sun. In addition to stars, there are many gas and dust masses in the Milky Way, called nebulae. Some nebulae contain a large number of molecules, called molecular clouds, which are often the places where stars form.

Outside the Milky Way, there are1000 billion huge celestial systems, which belong to the same structural level as the Milky Way and are collectively called galaxies. Andromeda galaxy, the farthest celestial body visible to the naked eye, is one of them. It is 2.25 million light-years away from the Milky Way, but it is the nearest galaxy of the same size. The distribution of galaxies in the universe is uneven, some in pairs, some in groups, and large clusters of galaxies even contain hundreds of galaxies. Some galaxy clusters have gathered into larger supercluster, and no uneven signs have been found between more than 500 million light-years and 654.38+0.5 billion light-years observed so far.

4. Collect five simple things about space.

Space is extremely cold, with an average temperature of-270.3℃.

In space, various celestial bodies also radiate electromagnetic waves, and many celestial bodies also radiate high-energy particles to form cosmic rays. For example, the sun has solar electromagnetic radiation, solar cosmic ray radiation and solar wind. Solar cosmic rays radiation is the high-energy particles emitted by the sun when a flare occurs, and the solar wind is the high-energy plasma stream blown out by the corona.

Many celestial bodies have magnetic fields, which capture the above high-energy charged particles and form radiation belts with strong radiation. For example, there are two radiation belts above the earth. It can be seen that space is still a strong radiation environment.

Space is still a high vacuum and microgravity environment. Gravity is only 1% to1100000 g (g- acceleration of gravity), while the gravity felt by people on the ground is1g.

So * * * spacesuit Humans can't survive in space.

There is little knowledge about the universe.

Constellation division Aries: March 2 1 to April 20 Taurus: April 2 1 to May 2 1 Gemini: May 22 to June 2 1 Cancer: June 22 to July 22 Leo: July 23 to August 23 Virgo:: 655. Kloc-0/October 22nd Sagittarius:165438+1October 23rd ~ 65438+February 20th.

As the earth revolves around the sun, from the perspective of the earth, the sun seems to move between constellations. People call the running route of the sun the ecliptic, and the running tracks of the moon and planets basically do not leave the narrow area of 9 degrees above and below the ecliptic, so people call this area the ecliptic. There were twelve zodiac signs in ancient times, and the sun basically passed one zodiac sign every month, so it was called the zodiac.

After the day, due to precession, the date when the sun passes through the zodiac is very different from that in ancient times. Introduction to Mercury Mercury is the closest planet to the sun, and its angular distance from the sun has never exceeded 28. In ancient China, Mercury was called a star.

In ancient times, Westerners thought that Mercury was two planets. When they see it at dusk, they call it mercury, and when they see it at dawn, they call it Apollo. Later, people knew that Mercury and Apollo were the same star, so they called Mercury Mercury.

Mercury was a messenger in Roman mythology who sent messages to the gods. He wears a hat with wings, flying shoes and a wand, and walks like a fly. He is omnipotent and unpredictable.

Mercury, like mercury, is really changing and elusive. In another month and a half, it will run from the easternmost end of the sun to the westernmost end, with an average speed of 47.89 kilometers per second, making it the fastest moving planet in the solar system. Venus is a simple introduction to Venus, which was called Taibai or Taibai Venus in ancient China.

It is sometimes the morning star, which appears in the eastern sky before dawn and is called "Qi Ming". Sometimes it is a dim star, which appears in the western sky after dusk and is called Chang Gung. Venus is the brightest star in the whole day except the sun and the moon, just like a dazzling diamond, so the ancient Greeks called it Aphrodite, the goddess of love and beauty, while the Romans called it Venus, the god of beauty.

In astronomy, the symbol of Venus is the precious mirror used by the beauty god when dressing. The earth is one of the nine planets in the solar system, and the third planet is arranged in the order from near to far from the sun.

It has a natural satellite-the moon, forming a celestial system-the earth-moon system. From near to far from the sun, Mars is the fourth planet.

To the naked eye, it is a striking bright lux star. It travels slowly among the stars. When looking at Mars from the earth, it sometimes goes straight and sometimes goes backwards.

The darkest apparent magnitude of Mars is about+1.5, etc. And at the brightest time, it is brighter than the brightest star Sirius, reaching -2.9. This is because the Earth and Mars are in their respective orbits, and the distance between them is always changing. Mars is as bright as fire, its brightness is constantly changing and its position is uncertain, which is confusing. So China called Mars "sparkling" in ancient times.

In western ancient Roman mythology, it was imagined as Mars, the god of war in armor and covered in blood, that is, Ares in Greek mythology. Ares had a noble life. His father is Zeus, the king of the gods, and his mother is Hera, the queen of heaven.

Astronomically, the symbol of Mars is the combination of the spear and shield of Mars. Introduction to Jupiter Jupiter is the most striking planet in the solar system. It is the oldest and largest of the nine planetary brothers.

Its brightness is second only to Venus. In ancient China, it was called the "year-old star", which was used to date the years because it was known that its period of revolution was close to 12.

The west calls Jupiter "Jupiter", the main god in Roman mythology. Equivalent to the king Zeus in Greek mythology.

Saturn is a beautiful planet, the sixth farthest from the sun. Anyone who has seen Saturn through a telescope will be surprised. Saturn's orbital radius is 65.438+0.4 billion kilometers, and its maximum brightness is 0.4 magnitude when it hits the sun.

On Saturn's orange surface, there are bright and dark clouds floating, and the soft and shiny halo on the equatorial plane looks like a girl wearing a sun hat from a distance. It is more than 6000 kilometers larger than the radius of the poles.

Saturn's period of revolution is 29.5 years, which is about 28 nights. It stays in the town for one night every year, so it was also called "Town Star" in ancient China. Saturn has always been regarded as the boundary of the solar system, and it was not until Uranus was discovered in 178 1 that the solar system began to expand.

Saturn moves slowly, so people regard it as a symbol of time and fate. In Roman mythology, he was called the Saturnalia, that is, Cronus in Greek mythology. He is the father of Zeus, the king of the gods, who overthrew his father and ascended the throne of the gods.

Both the East and the West associate Saturn with agriculture. Symbols in astronomy are like scythes that dominate agriculture.

Introduction to Uranus It is not difficult to watch Uranus on a clear night. Its magnitude is 5.7.

Its period of revolution is quite long. It orbits the sun once every 84 years, moving only 46 inches a day on average. It is not easy to distinguish it from a star. In history, it has been mistaken for many times that stars are loaded into star maps. Introduction to Neptune The average distance from the sun is arranged from near to far, and Neptune ranks eighth.

Its brightness is 7.85 and so on, which can only be seen in a telescope. Because it is a light blue planet, it is named Neptune according to the traditional planetary nomenclature.

Neptune is the sea god who rules the ocean in Roman mythology. He is in charge of the universe of13, which is quite amazing. Neptune's astronomical symbol symbolizes the cold shiny fork in Neptune's hand. Asteroids refer to small celestial bodies that are mostly distributed between the orbits of Mars and Jupiter and orbit around the sun along elliptical orbits.

180 1 year, Italian astronomer Piazi discovered a star in the position predicted by his predecessors, and later named it ceres. However, after further observation and calculation, it is found that Ceres is too small to be compared with the existing planets in any case, so Ceres is characterized as an "asteroid".

Then people discovered pallas Athena, Vesta, Vesta and other asteroids.