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The Milky Way is the galaxy to which the earth and the sun belong. It is named because the bright band whose main part is projected on the celestial sphere is called the Milky Way in China.

There are about 200 billion stars in the Milky Way.

The Milky Way looks like a big disk with a slightly protruding center. The diameter of the whole disk is about 654.38+ million light years, and the sun is located 33,000 light years away from the center of the Milky Way. What bulges is a silver heart, which is a dense area of perseverance, so I look at a vast expanse of whiteness.

The Milky Way looks like a huge whirlpool from the top, which consists of four propaganda arms. The solar system is located in one of the spiral arms (Orion arm) and rotates counterclockwise (it takes 250 million years for the sun to rotate around the center of the Milky Way).

The Milky Way is a whirlpool, and four spiral arms extend evenly and symmetrically from the center of the Milky Way. The center of the Milky Way and the four spiral arms are places where stars are concentrated. From a distance, the Milky Way looks like a discus for exercise. The diameter of discus is 65.438+million light years, equivalent to 946.08 billion kilometers. The thickest part in the middle is about 3000 ~ 6500 light years. The sun is located on a spiral arm called Orion arm, about 33,000 light years away from the center of the Milky Way.

solar system

The solar system is the star system in which we are now. It consists of the sun, eight planets (originally there were nine planets because Pluto was excluded from dwarf planets), 66 satellites (originally there were 67, Pluto's satellites were excluded) and countless asteroids, comets and meteorites. The order of planets from the sun is: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. Mercury, Venus, Earth and Mars near the sun are called terrestrial planets. Spacecraft have all detected and landed on Mars and Venus, and achieved important results. Their common characteristics are high density (>: 3.0 g/cm3), small volume, slow rotation, few satellites, mainly silicate inside and firm shell. Jupiter, Saturn, Uranus and Neptune, which are far away from the sun, are called woody planets. They all have a thick atmosphere, and their surface features are difficult to understand. Generally speaking, they all have solid cores similar to terrestrial planets. There are more than 1000000 asteroids (that is, irregular small stars composed of rocks) between Mars and Jupiter. It is speculated that they may be formed by fragments of a planet between Mars and Jupiter, or some rock fragments failed to accumulate into a unified planet. Meteorites exist between planets and are made of stone or iron.

All these planets revolve around the sun in elliptical orbits, although it is very close to a circle except Mercury. Planetary orbits are more or less in the same plane (called ecliptic plane, based on the orbital plane of the earth). The ecliptic plane is only 7 degrees from the equator of the sun. Pluto's orbit is mostly outside the ecliptic, with an inclination of 17 degrees. The above picture shows the relative size and relationship of each orbit from a specific perspective higher than the ecliptic plane (non-circular phenomenon is obvious). Their orbits run in the same direction (counterclockwise from the north pole of the sun), so scientists exclude Pluto from the nine planets. Except Venus and Uranus, the rotation direction is the same.

The position of the solar system in the universe

The solar system is located at the edge of the Milky Way, the third spiral arm of the Milky Way-Orion spiral arm.

The solar system is a celestial body system, which consists of the sun and celestial bodies orbiting the sun under its gravity. It includes the sun, eight planets and their satellites, asteroids, comets, meteoroids and interplanetary matter. The earth where human beings live is a member of the solar system.

Comments (4)|48

Asajj | Level 1

How many stars are there in the Milky Way?

Sagittarius A is very small, only equivalent to the size of an ordinary star. The radio emission intensity of Sagittarius A is 2 *10 (34th power) erg/s, which is located within 0.2 light-years of the dynamic center of the Milky Way. It is surrounded by moving ionized gas with a speed as high as 300 km/s, and there is a strong infrared radiation source. It is known that the activities of all star-level celestial bodies cannot explain the peculiar characteristics of Sagittarius A, so Sagittarius A seems to be the best candidate for massive black holes. However, because there is no conclusive evidence of massive black holes at present, astronomers carefully avoid mentioning massive black holes in conclusive language. Our Milky Way contains about 200 billion stars, including about 1000 billion stars, and the sun is a typical one. The Milky Way is a fairly large spiral galaxy, which has three main components: a silver disk with spiral arms, a silver center protruding from the center and a halo.

The spiral galaxy M83 is very similar to our Milky Way in size and shape.

Silver plate:

The silver disk is the main body of the galaxy, with a diameter of about 80,000 light years, a thickness of about 6,000 light years in the middle and a thickness of about 3,000 light years near the sun. The silver plate is mainly surrounded by four huge spiral arms and consists of countless blue stars. The sun lies on the arm of Orion between Sagittarius and Perseus, 28,000 light years away from the galactic center or 8,500 parsec. The formation of spiral arms is related to the activity of galactic nuclei during the formation of the Milky Way.

The galaxy ngc89 1, the side of the Milky Way is like this.

Silver heart:

The central bulge of the galaxy is a bright sphere with a diameter of about 20,000 light years and a thickness of 10000 light years. This region consists of high-density stars, mainly red stars over10 billion years old. Many evidences show that there is a huge black hole in the central region, and the activity of galactic nuclei is very intense.

Silver halo:

The galactic halo is scattered in a spherical area around the silver disk. The diameter of the silver halo is about 98,000 light years. The density of stars here is very low, and there are some globular clusters of old stars. Some people think that there is a huge spherical radio emission area outside the silver halo, called the silver corona, which extends at least 1000 parsec or 320,000 light years from the silver center.

Respondent: a bird yearning for freedom-the second level of entering the Jianghu 3-27 20:23

What is the Milky Way?

If we scan the sky roughly with the naked eye, it seems that we have seen all the stars in the sky. There is no place where the stars look particularly dense, and there is no place where the stars look particularly sparse. From this, we can draw a conclusion that, for us, stars are evenly distributed in all directions. If the stars as a whole can form an aggregate of a certain shape, then the shape must be spherical. Obviously, all large celestial bodies are similar to spheres. Why can't the whole galaxy be regarded as a sphere?

Of course, there are only 6,000 stars that we can see with the naked eye, and most of them are quite close to us. What will we find if we use a telescope? The answer is that we see more stars, which seem to be evenly distributed in the sky-except the Milky Way.

To the naked eye, the Milky Way is a weak band of light (now if we live in a city, it is difficult to see the Milky Way because the sky is artificially illuminated). It looks pale milky white. In fact, there is a fairy story about it: a long time ago, when Zeus' wife Hera was breastfeeding her baby, her milk flowed into the sky, forming this faint light band. The Greeks called it galaxias kyklos (silver ring), and the Romans called it via lactea (Galaxy), from which we got its English name.

But what is the real Milky Way? If we don't consider fairy tales, then we can first think of the ancient Greek philosopher democritus. Around 440 BC, he proposed that the Milky Way actually consists of a large number of stars, which cannot be distinguished separately. But they gather together to give off a soft light. Although this view has not attracted people's attention, it is completely correct. 1609, Galileo aimed the first telescope at the sky and found that the Milky Way contains a large number of stars. This theory was confirmed.

What do you mean by "a huge number"? When people look at the night sky, their first impression is that there are countless stars, too many to count. But I mentioned several times that the total number of stars visible to the naked eye is only about 6000, and the number of stars seen through telescopes is much more. Does this mean that they are countless?

Stars in the direction of the Milky Way are very dense, while those in other directions are relatively rare, which means that we must abandon the whole concept of stars forming spherical structures. In that case, there should be as many stars in all directions as there are in the direction of the Milky Way. Under the background of weak light, the closer stars twinkle (not as spectacular as it is now), and the whole sky will be illuminated.

Then, we must assume that stars exist in large aspherical clusters and extend farther in the direction of the Milky Way than in other directions. In this case, the Milky Way galaxy shows that all the stars gather in the shape of a lens or hamburger. This lens-shaped cluster is called the Milky Way (Greek explanation comes from the Milky Way), and the name of the Milky Way has been preserved because of the dark light band around the sky we see.

The first person to suggest that stars exist in shadow galaxies is thomas wright, a shadow astronomer. He put forward this suggestion in 1750, but his idea seemed so confusing and incomprehensible that few people paid attention to him at first.

Of course, even if the Milky Way is lens-shaped, it can always extend in the long diameter direction. Although only a few stars can be seen outside the Milky Way, there are countless stars inside the Milky Way.

To illustrate this problem, William Herschel calculated the number of stars. It is naturally impossible to count all the stars in a certain period of time.

Herschel chose 683 small areas, evenly distributed in the sky, and then counted the stars seen through the telescope in each area. In this way, he got the number of stars that we now call "imaginary voting" in the sky. This is the first example of the application of statistics to astronomy.

Herschel believes that the number of stars in each region is related to its proximity to the Milky Way. In all directions, the number of stars increases steadily as they approach the Milky Way. From the number of stars he counted, we can estimate the number of stars in the Milky Way and the possible size of the Milky Way. 1785, he announced the results, and proposed that the long diameter of the Milky Way is about 800 times the distance from the sun to Sirius, and the short diameter is 150 times this distance.

Half a century later, the actual distance of Sirius was calculated, and Herschel concluded that the long diameter of the Milky Way was 8000 light years and the short diameter was 1500 light years. At the same time, he calculated that there are 8 billion stars in the Milky Way. Although this is a huge number, it is not uncountable.

In the past two centuries, astronomers have explored the Milky Way with much better instruments and techniques than Herschel can use. Now they know that the Milky Way is much bigger than Herschel expected. It extends at least 654.38 million+light-years in the long diameter direction and may have 200 billion stars. However, it can be said that we have confirmed that galaxies and stars are not numerous but computable, thanks to Herschel.

Galactic System

The sun is a member of a huge disk system composed of stars and galaxies. The light from many stars in the Milky Way formed the Milky Way, which became an irregular luminous band around the night sky. This starlight belt is generally located on the plane of the silver plate. The Milky Way is one of the billions of galaxies that make up the universe. It has tens of billions of stars and a considerable amount of interstellar gas and dust. The Milky Way is a typical spiral galaxy in the galaxy type. Its core is surrounded by a huge central nuclear ball, surrounded by spiral arms. These curved arms make the shape of the Milky Way look like a giant wheel. The spiral arms sink evenly into the silver plate. The silver disk is the main part of the Milky Way, with a diameter of about 70,000 light years. The silver core is shielded by interstellar dust particles and absorbs visible light and ultraviolet light in silver nuclear radiation. However, scientists can record and study the radiation emitted by silver nuclei in radio, infrared, X-ray and γ-ray bands. In particular, the intense emission of infrared radiation and X-rays indicates the existence of ionized gas clouds moving at high speed. It is generally believed that this gas cloud is orbiting a massive celestial body, which is likely to be a black hole with a mass of about 4 million suns. Scientists have confirmed that the main components of the central nuclear sphere are some ancient stars and ancient clusters. The composition of the spiral arm is a completely different celestial body. The celestial bodies in the spiral arms belong to very young bright stars and open clusters. In addition, the spiral arm region is the region with the highest concentration of interstellar gas and dust particles, so it is also the most suitable place for the formation of new stars. The sun is located near the inner edge of one of these spiral arms, the Orion arm, with a radius of about two-thirds from the center of the Milky Way. The silver core is located in the direction of Sagittarius, about 23,000 light years away from the sun. Above and below the silver plate is a spherical area (called spherical component), which is full of globular clusters and other very old celestial bodies. Such as dwarfs that are poor in heavy elements. The periphery of the Milky Way reaches the visible edge, which is a huge silver halo with huge mass. Its composition, shape and extension are not very clear. The whole galaxy revolves around the center of the galaxy, but celestial bodies with different compositions do not rotate at the same speed. Objects far from the galactic center are slower than those near the galactic center. The sun, which is quite far away from the galactic center, orbits the galactic center in an approximate circular orbit with an estimated speed of 225 km/s. Because of the slow revolution speed of the sun, it takes about 200 million years for it to orbit the galactic center once.

The solar system where the earth is located is in the Milky Way. Looking at the Milky Way on the earth, you will find a milky white bright belt across the starry sky, which is the projection of the main body of the Milky Way on the celestial sphere. China was also called Han Yin in ancient times. In the northern half-day, the Milky Way starts from the eagle to the northwest, passes through Sagittarius, Fox, Cygnus, Cepheus and Cassiopeia, then turns to the southeast, passes through Perseus, Auriga, Taurus, Gemini and Orion, passes through the unicorn on the equator of the celestial sphere, enters Canis Canis, Pisces and Vela in the southern half-day, turns to the northwest, and passes through the carina and carina. After 23 constellations, the Milky Way returned to Aquila on Sunday. Through the telescope, we can see that the Milky Way is made up of countless stars and nebulae. Nebulae are bright and dark. Dense and bright star clouds illuminate the Milky Way, for example, the bright areas around Shield and Sagittarius. Dark nebulae appear in the form of dark areas in the Milky Way, such as the "Big Bifurcation" south of Aquila and the "Coal Bag" near the Southern Cross. The Milky Way draws a belt with irregular outline and inconsistent width in the starry sky, which is called the Galaxy Belt. The widest part of the Silver Island Belt is 30, and the narrowest part is above 10.

Astronomical galaxy

At the beginning of the 20th century, Kapteyn established a 40,000-light-year-long model of the Milky Way with the solar system as the center through the statistical study of star counting and luminosity function. 19 18, shapley challenged the traditional idea that the solar system is the center of the Milky Way. He analyzed the apparent distribution of globular clusters known at that time, and estimated their distance according to the period-luminosity relationship, that is, Cepheid variable stars, and concluded that the Milky Way is a lens-shaped star and nebula system with a diameter of 300,000 light years and a thickness of 30,000 light years. The center of the Milky Way is in the direction of Sagittarius, and the sun is 50,000 light years away from the center of the Milky Way. This is a feat to declare that the solar system is not at the center of the universe since Copernicus Heliocentrism. For half a century, the form of shapley model has stood the test of new observation facts and been recognized by the world. However, due to the wrong assumption that there is no light-absorbing substance between stars, the distance scale is overestimated. Until 1930, trumpler confirmed the existence of interstellar light absorption by studying galaxy clusters, and then revised the size of the galaxy model again. Today, the recognized value is about 8 1 1,500 light years in diameter, about 3,300 ~ 6,600 light years in thickness, and about 32,600 light years from the center of the Milky Way.

1926, Lindblad pointed out that the asymmetric effect of star motion is a reflection of the rotation of the Milky Way. Later, Oort confirmed the poor rotation of the Milky Way and found that the sun moves in a circular orbit around the center of the Milky Way at a speed of 250 kilometers per second, which is estimated to be once every 250 million years. He also estimated that the mass of the Milky Way is 1.4× 10□ the mass of the sun. According to the revelation of extragalactic galaxies, it is speculated that the Milky Way also has a vortex structure. In the early 1950s, Morgan's research on the spatial distribution of high luminosity stars and the radio analysis of neutral hydrogen 2 1 cm lines by Oort et al. accurately described the spiral structure and spiral arms of the Milky Way. In 1960s, Lin Jiaqiao successfully explained the vortex structure and its maintenance mechanism with the density wave theory.

1944, Budd put forward the concept of star family based on the study of Herro diagram of cluster, and divided the stars into two categories: star family ⅰ and star family ⅱ. 1957, at an international academic conference held in the Vatican, according to the parameters such as the speed of star space movement, the distance from galactic plane, the concentration of galactic center, the helium content and age, the star groups were subdivided into intermediate group ⅰ, spiral arm group ⅰ, disk group ⅱ and halo group ⅱ. The member celestial bodies of these five subsystems constitute a silver crown, a silver halo, a silver heart, a silver disk and a spiral arm.

Galaxy World 19 12, Loewit observed the Cepheid variable in small magellanic cloud and found the period-luminosity relationship, thus inferring that the distance of small magellanic cloud may be very far away, possibly outside the Milky Way. At the end of 1924, Hubble announced that the distance between Andromeda (M3 1) and Sagittarius irregular galaxy (NGC6822) was calculated by using the Zao Fu period-luminosity relationship, and pointed out that they were star systems outside the Milky Way. Since then, galaxy astronomy was born. The ancient concept of cosmic island has been proved to exist objectively; The establishment of the concept of "the universe outside the milky way" is another great achievement of astronomy in the twentieth century.

1929, Hubble found that the red shift of spectral lines of extragalactic galaxies is directly proportional to the distance between galaxies. If redshift is recognized as the Doppler effect of celestial regression, then the redshift-distance relationship means that galaxies are generally regressing, and the space in which they are located is expanding as a whole. The expansion of the universe is one of the expected results of relativistic cosmology. 1956, M.L. Hammason extended the linear relationship between redshift and distance to redshift □=0.20, that is, the regression speed reached 1/5 of the speed of light. 1977, the Alexander lattice expanded to □=0.75, that is, the backward speed was half the speed of light. According to this, the distance has exceeded 5 billion light years. This is the observation basis that we live in a constantly moving and evolving universe.

In 1960s, at 10 □ ~ 10 □, compared with most normal galaxies with the evolution scale of 10□ years, their existence was only a brief moment. Since 1970s, exploring the deep space more than 10 billion light-years away has become the main topic of modern astronomy.

Galaxy system

Our Milky Way contains about 200 billion stars, including about 1000 billion stars, and the sun is a typical one. The Milky Way is a fairly large spiral galaxy, which has three main components: a silver disk with spiral arms, a silver center protruding from the center and a halo.

Silver plate:

The silver disk is the main body of the galaxy, with a diameter of about 80,000 light years, a thickness of about 6,000 light years in the middle and a thickness of about 3,000 light years near the sun. The silver plate is mainly surrounded by four huge spiral arms and consists of countless blue stars. The sun lies on the arm of Orion between Sagittarius and Perseus, 28,000 light years away from the galactic center or 8,500 parsec. The formation of spiral arms is related to the activity of galactic nuclei during the formation of the Milky Way.

Silver heart:

The central bulge of the galaxy is a bright sphere with a diameter of about 20,000 light years and a thickness of 10000 light years. This region consists of high-density stars, mainly red stars over10 billion years old. Many evidences show that there is a huge black hole in the central region, and the activity of galactic nuclei is very intense.

Silver halo:

The galactic halo is scattered in a spherical area around the silver disk. The diameter of the silver halo is about 98,000 light years. The density of stars here is very low, and there are some globular clusters of old stars. Some people think that there is a huge spherical radio emission area outside the silver halo, called the silver corona, which extends at least 1000 parsec or 320,000 light years from the silver center.

Galaxy system

The star system in which the solar system is located includes120 billion stars, a large number of star clusters and nebulae, and various types of interstellar gas and dust. Its total mass is 654.38+04 billion times that of the sun. Most of the stars in the Milky Way are concentrated in a oblate sphere, which is shaped like a discus. The protruding part in the middle of the oblate sphere is called the "nuclear sphere" with a radius of about 7000 light years. The center of the core ball is called "silver core" and the periphery is called "silver disk". There is a bigger sphere outside the silver disk, where there are fewer stars and less density. It is called "Silver Halo" with a diameter of 70,000 light years. The Milky Way is a spiral galaxy with a spiral structure, that is, it has a silver center and two spiral arms, which are 4500 light years apart. The rotation speed and period of each part of it are different because the distance from the silver center is different. The sun is about 23,000 light years away from the galactic center, and it orbits the galactic center at a speed of 250 km/s with a period of about 250 million years.

Scientific terminology: Milky Way

The Milky Way is a galaxy, slightly larger than ordinary galaxies, with a diameter of about100000 light years. There are at least 200 billion stars in the Milky Way. Among them, about 40 billion stars are concentrated in the central bulge, surrounded by four spiral arms, and the area is mixed with gas and dust. The nuclear sphere is an ellipsoid with a diameter of 3000 light years, which is composed of old planets over 65.438+0 billion years old. The history of the Milky Way is 654.38+0.5 billion light years.

Galaxy system

The galaxy, the star system where the earth and the sun are located. It is an ordinary galaxy, named after its milky white bright band projected on the celestial sphere-the Milky Way. The Milky Way is disc-shaped, with a diameter of 25,000 parsec and a thickness of about 1-2000 parsec. This flat star system is called the silver disk. There are spiral stars, clusters and nebulae on the silver disk. There is a huge nuclear ball in the center of the silver plate, which is shrouded in a silver halo with a diameter of about 30,000 parsec. The mass of the Milky Way is about 1.4× 10 1 solar mass, of which 90% are stars, and 10% are interstellar matter composed of gas and dust. The galaxy as a whole rotates badly. It takes 250 million years for the sun to rotate around the silver center at a speed of 250 kilometers per second in a silver disk about 65,438+00 thousand parsec away from the silver center. The Milky Way is the largest galaxy in this galaxy group except Andromeda, with about120 billion stars. Its evolution time scale is 10 10 years, and its absolute magnitude is MV=-20.5.

Galileo was the first person to discover with a telescope that the Milky Way is made up of stars. /kloc-In the late 8th century, William Herschel made a systematic observation of star counting with a self-made reflecting telescope. He counted 65,438+065,438+07,600 stars and drew a plane uneven structure map of the Milky Way with the sun as the center. Because he didn't know the existence of interstellar extinction and made a simplified assumption that all stars have the same luminosity, his conclusion was far from the fact. After the death of William Herschel, his son John Herschel extended the work of counting stars to the southern half of the sky and drew a map of the whole sky. 190 1 year, Kapteyn measured the average distance of stars by statistical parallax method, and found that the Milky Way galaxy is 8,000 parsec in diameter and 2,000 parsec in thickness, with the sun in the center, dense central stars and sparse edges. 19 18, shapley proposed a lenticular model of the Milky Way galaxy with the sun out of the center. This work is based on the study of the period-luminosity relationship of Cepheid variable stars, and has been recognized by the astronomical community. However, without considering the effect of interstellar extinction, shapley also overestimated the Milky Way. In 1930, this deviation was corrected by trumpler.

After the birth of radio astronomy, the vortex structure of the Milky Way was outlined by using the neutral hydrogen 2 1 cm spectral line, and it was found that there were three spiral arms near the sun. Using radio astronomy to observe various interstellar molecules such as OH, ch and CN enriches the overall structure of the Milky Way.

According to BIGBANG's cosmological hypothesis, the Milky Way was gradually formed by the gravitational instability of BIGBANG 10 10 years ago. In recent years, people have discussed the overall evolution process of the Milky Way from the perspectives of the formation and evolution of stars, the changes of element abundance, the activities of silver nuclei and their position in evolution. In 1960s, the density wave theory put forward by Lin Jiaqiao and others well explained the maintenance mechanism of the spiral structure of the Milky Way.

Galaxy system

The Milky Way contains about 200 billion stars, including about 1000 billion stars-our sun is one of them. It is a typical spiral star system with a diameter of about100000 light years, and the sun is about 28000 light years away from the center of the Milky Way. The Milky Way has three main components: the silver disk, the silver core and the halo.

Silver plate:

The silver disk is the main body of the galaxy, with a diameter of about 80,000 light years, a thickness of about 6,000 light years in the middle and a thickness of about 3,000 light years near the sun. The silver plate is mainly surrounded by four huge spiral arms and consists of countless blue stars. The sun lies on the arm of Orion between Sagittarius and Perseus, 28,000 light-years or 8,000 or 5,000 parsec from the center of the Milky Way. The formation of spiral arms is related to the activity of galactic nuclei during the formation of the Milky Way.

Central convex part

The central bulge of the galaxy is a bright sphere with a diameter of about 20,000 light years and a thickness of 10000 light years. This region consists of high-density stars, mainly red stars over10 billion years old. Many evidences show that there is a huge black hole in the central region, and the activity of galactic nuclei is very intense.

Halo part

The galactic halo is scattered in a spherical area around the silver disk. The diameter of the silver halo is about 98,000 light years. The density of stars here is very low, and there are some globular clusters of old stars. Some people think that there is a huge spherical radio emission area outside the silver halo, called the silver corona, which extends at least 1000 parsec or 320,000 light years from the silver center.

On a clear night without light interference, if the sky is dark enough, you can see the diffuse light bands in the sky. This band of light is what we see when we look at the Milky Way from the inside. It is a round surface full of stars-a silver disk. There are about 200 billion stars in the Milky Way, but they are too far away to be recognized by the naked eye. Because starlight is mixed with interstellar dust gas, it looks like a band of light shrouded in smoke. The center of the Milky Way lies near Sagittarius. The Milky Way is a medium-sized star system, and its silver disk is about120,000 light years in diameter. Its silver disk contains a lot of interstellar dust and gas clouds, which gather into a red star-forming area, thus constantly supplementing the spiral arms of galaxies with hot young blue stars, forming many open clusters or clusters of galaxies. There are more than 1200 such open clusters. Around the silver disk is a huge silver halo dotted with stars and globular clusters mainly composed of old stars.

From our point of view, it is difficult to know exactly the shape of the Milky Way. However, with the development of modern science and technology, the progress of detection means has overcome these obstacles to some extent and revealed some unexpected characteristics of the Milky Way. For a long time, people thought that the Milky Way was a typical spiral galaxy, similar to Andromeda. However, recent observations show that its central nuclear sphere is slightly rod-shaped. This means that the Milky Way galaxy is probably a rod-spinning galaxy. In addition, the Milky Way is a relatively active galaxy, the silver core has strong cosmic ray radiation, and the stars rotate at high speed around an invisible center. This shows that there is a supermassive black hole in the core of the Milky Way.

The Milky Way has two smaller neighbors-large magellanic cloud and small magellanic cloud, both of which belong to irregular galaxies. Because of gravity, the Milky Way constantly absorbs dust and gas from these two small galaxies, making the matter in these two neighbors less and less. It is predicted that after10 billion years, the Milky Way will devour all the materials in these two galaxies, and these two close neighbors will no longer exist.

1 astronomical unit (au) =1.49597870e11m.

1 light year = 9.460536E 15m =63239.8 astronomical unit.

1 parsec (PC) = 3.085678e16+06m = 206264.8 astronomical unit =3.26 163 1 light-year.

1 mile = 1.6444 km.

1 angstrom =1e-8cm =1e-10m

time

Day: average sidereal day (vernal equinox to equinox) =86 164.094 average solar seconds.

The average rotation period of the earth (from star to star) = 86 164.4438+002 solar seconds.

Average solar day =86400 average solar seconds

Month: node month = 27.21222nd =27: 05: 35.808 seconds.

Vernal equinox month (vernal equinox) = 27.32158 = 7: 43 on the 27th, 4.5 12 second.

Nearby month =27.55455 days =27, 13, 18, 33. 124 seconds.

Shuowangyue =29.53059 =29, 12: 44: 2.976.

Star time =27.32 166 days = 7: 43 on the 27th, 1 1.424 seconds.

Year: food year (from yellow to white intersection) =346.6200 days.

Tropic year (from vernal equinox to vernal equinox) =365.2422 days.

Gregorian calendar year =365.2425 days

Julian year =365.2500 days

Stellar year =365.2564 days

Last year =365.2596 days

Based on internet