These hundreds of years of exploration and changes are driving a new generation of young people like Huafeng to move forward unswervingly towards the future.

1750 - British astronomer Wright

ight Thomas) argues that the Milky Way is flat.

1755 – The German philosopher Immanuel Kant proposed that a huge celestial system might form between the stars and the Milky Way;

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Similar hypotheses were put forward.

1785 - The British astronomer William Herschel uses the method of "counting the stars" to draw a map of the Milky Way, in which Herschel is flattened and surrounded by stars, 7,000 light-years long and 1,400 light-years wide. Our Sun is at the center of the Milky Way, the first model of the Milky Way established by mankind, and although it is very imperfect, it expands the horizon from the solar system to the vast stellar world of the Milky Way.

1845 – Lord Ross discovers the first spiral galaxy, M51.

1852 - American astronomer Stephen Alexander claims that the Milky Way is a spiral galaxy, but there is no evidence to prove it.

1869 – The English astronomer Richard Protock makes the same opinion, but it is equally unprovable.

1900 - Dutch astronomer Cornelius Easton publishes a diagram of the Milky Way's vortex structure, but the spiral arms and silver heart are incorrectly drawn.

In 1904, the discovery of ionized calcium spectral lines in the stellar spectrum revealed the existence of interstellar matter. Subsequent spectroscopy and polarization studies confirmed the identification of gas and dust components in the nebula.

In 1905, Herzplon discovered that stars were divided into giants and dwarfs.

In 1906, in order to re-study the structure of the stellar world, Kaptan proposed the "Select Star District" plan, which was later called the "Kaptan Constituency". He came up with a similar model to F.W. Herschel's in 1922, a flat system with the Sun in the center and a dense center of stars with sparse edges. On the assumption that there is no significant interstellar extinction, a lenticular model of the Milky Way was established in 1918, with the Sun not in the center.

By the twenties, the Shapley model had gained acceptance in the astronomical community. By not accounting for the interstellar extinction effect, Shapley overestimated the Milky Way. This discrepancy was not corrected until 1930, when Taunter confirmed the existence of interstellar matter.

In 1913, after the advent of the Herot chart, according to the two parameters of spectral type and luminosity, it was learned that in addition to the main sequence star, there were five branches: supergiant, giant, subgiant, subdwarf and white dwarf. Cornelius Easton has once again published a false diagram of the Milky Way's vortex.

In 1917, the American astronomer Shapley (Ha

low Shapley used the 2.5-meter reflecting telescope at the Mount Wilson Observatory to study the 100 globular clusters known at the time, and determined the distance of these globular clusters by observing the Cepheids in them.

In 1922~1924, the American astronomer Hubble discovered that not all nebulae are in the Milky Way. After analyzing the brightness of a group of Cepheids on the M31 Andromeda Nebula, Hubble concluded that these Cepheids and the nebula in which they are located are hundreds of thousands of light-years away from us, and therefore must be located outside the Milky Way. The discovery, published in 1924, forced astronomers to change their view of the universe.

1926 - Swedish astronomer Lid Bullard

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til) analyzed that the Milky Way is also rotating.

In 1927, the Dutch astronomer Olter measured the poor rotation of the Milky Way, further proving that the Sun was indeed not at the center of the Milky Way.

1929 – Dutch astronomer Bart Bock's plan to use stellar counting to detect the structure of the Milky Way fails more than a decade later.

1931 – Bard works at the Mount Wilson Observatory and begins to develop the concept of star clans.

1943 – William Mo

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Together with spectroscopist Philips Keenan, he published a complete spectral atlas to describe the spectral characteristics of stars of different spectral types and luminosities, called the MK (Morgan-Keenan) classification system.

In 1944, through the observation of the Andromeda Galaxy, Bard determined that stars can be divided into two different star families: Star Race I and Star Group II. Constellation I is a young, metal-rich celestial body distributed on a spiral arm that is in harmony with interstellar matter. Star Clan II is an old, metal-poor celestial body with no tendency to concentrate on the galactic plane.

1947 — The MK system is used to depict the spiral arms of the Milky Way.

1950 — At a distance of 49 OB single stars and three OB constellations, a clear spiral arm structure cannot be revealed. At the same time, he was inspired by Bard to observe and delineate the HII region in the Milky Way, and use the OB type stars located in it to determine the distance. Through radio observations, it was found that there are a large number of gases in the interstellar space of the Milky Way, especially neutral hydrogen, which are found throughout almost the entire Milky Way, and these gases emit radio waves with a wavelength of 21 centimeters. Once the distribution of these neutral hydrogen clouds in the Milky Way was understood, they speculated about the general shape of the Milky Way, believing it to be a spiral galaxy.

1951 - Scientists discovered for the first time that the Milky Way has three spiral arms. The location of the HII region was plotted on a map of the Milky Way, revealing two spiral arms, namely the Orion Arm and the Perseus Arm, which were presented at the annual meeting of the American Astronomical Society in the same year, proving that the Milky Way belongs to the spiral galaxy type.

In 1957, according to the metal content, age, spatial distribution and movement characteristics, the two star families were subdivided into intermediate star group I., spiral arm star group (extreme star group I.), disk star group, intermediate star group II., and halo star group (extreme star group II).

1964—Chinese-American scientists Jiaqiao Lin and Yaosheng Xu propose the theory of maintaining density waves for spiral arms of spiral galaxies, which preliminarily explains the stability of spiral arms, and they suggest that spiral arms are only displays of spiral density waves.

In the seventies and eighties of the 20th century, people explored the distribution of carbon monoxide molecules in the Milky Way, and discovered a fourth spiral arm, which spanned the constellations Fox and Cygnus. In 1976, two French astronomers mapped the positions of these four spiral arms in the Milky Way: Compass, Shield-Centauri, Sagittarius, and Perseus.

In 1971, British astronomers Lyndon Bell and Martin Ness analyzed infrared observations and other properties of the central region of the Milky Way, pointing out that the energy source at the center of the Milky Way should be a black hole.

1982—American astronomers Janas and Adler complete a chart of 434 galactic stars in the Milky Way, publishing the distance and age numbers for each star cluster. They found that the Milky Way does not have a vortex structure, but only a small fragment of spiral arms, and the vortex is just a kind of "phantom", because the stars produced in the Milky Way always form a kind of "bead" in the direction of rotation of the Milky Way. And the constant creation of new stars continuously shows the phantom of the vortex.

1989 - How far is the Sun from the galactic center? This so-called "galactic distance" is a fundamental and important parameter for the Milky Way. For more than 70 years since 1918, there have been discussions on the spatial distribution of globular clusters. Many people try to apply different ways to research. Scientists have come up with different values, ranging from a minimum of 22,800 light-years to a maximum of 27,700 light-years. The result for 1989 was 24,400 light-years, with a possible error of 3,000 light-years above and below. In this way, the Sun and the Solar System bodies are located relatively close to the middle of the Milky Way.

2004—Astronomers using the Very Large Telescope's (VLT) ultraviolet vision matrix spectrometer have discovered beryllium for the first time in two stars in globular cluster NGC 6397. This discovery allowed them to advance the alternation of the first generation of stars by 2 to 300 million years, so that the age of the globular cluster is estimated to be 13±48 billion years old, so the age of the Milky Way will not be less than 13±68 billion years old.

2005—Scientists using the Spitzer (Spitzer) infrared space telescope conducted a panoramic scan of the center of the Milky Way, and after analyzing the scans, they concluded that the center of the Milky Way is a rod-shaped structure. Astronomers say the rod is about 27,000 light-years long, 7,000 light-years longer than earlier estimates, and that it points in an direction about 45° relative to the angle between the Sun and the galactic center. The results of this study confirm earlier speculations about the shape of the Milky Way: the Milky Way is not a simple spiral galaxy, but an SBc barred spiral galaxy with a barred nucleus (a barred spiral galaxy with loose arms) with a total mass of about 600 billion to 3,000 billion times the mass of the Sun. There are about 100 billion stars. The Milky Way's disk is estimated to be 100,000 light-years in diameter, and the distance from the Sun to the center of the Milky Way is about 26,000 light-years, with the disk convex outwards in the center.

2006 – There is a much larger distribution of matter outside the galactic halo of the Milky Way, which is a place of great concern to scientists today, because there may be a large amount of dark matter in the halo. In January 2006, scientists announced that they had confirmed that the Milky Way was bent and deformed, and that the force that caused it to deform came from the dark matter stirring around its periphery. Scientists explain that dark matter, although invisible, can be 20 times more massive than the visible matter in the Milky Way, so the impact on celestial bodies in the Milky Way cannot be underestimated.

2008 — Another issue of concern is the "Sagittarius A* (Sagitta

ius A*)": A radio emission source located in the heart of the galaxy that has puzzled for years. Astronomers have long suspected that it is a huge black hole at the center of the Milky Way, but it has never been conclusively confirmed.

In 2008, scientists announced that they had confirmed the existence of a black hole in the galactic center through observations. Scientists spent 16 years tracking 28 stars orbiting the galactic core at the European Southern Observatory in Chile, thus confirming the existence of black holes, which affect the orbit of these stars. Detections have shown that the giant black hole, called Sagittarius A*, is 4.2 million times more massive than the Sun and is about 26,000 light-years away from Earth.