The vast interstellar space between hundreds of billions of stars in the Milky Way is not nihility, but full of rare interstellar media. Chinese scientists have recently used the "China Tianyan" FAST to reveal the unprecedented high-definition details of the galactic interstellar medium, which is of great significance to the study of the interstellar ecological cycle in the Milky Way. The research was completed by a scientific research team led by Han Jinlin, a researcher at the National Astronomical Observatory of the Chinese Academy of Sciences, and a series of papers were published as special topics in the academic journal Science in China: Physics, Mechanics and Astronomy on the 10th. "The interstellar medium of the Milky Way Galaxy hides the mystery of the life and death of stars, which has always been the goal of astronomers to explore." Han Jinlin introduced that hydrogen atom gas is widely distributed in the Milky Way, and dense hydrogen atoms converge to cool, forming hydrogen molecular clouds, which breed a new generation of stars in the high-density cloud core; Stars continue to evolve, some of which eventually explode into supernovae, generating supernova remnants and pulsars; The explosion shock wave can compress the interstellar space gas and accelerate the electrons to the speed close to the speed of light. These high-speed electrons move in the interstellar magnetic field and radiate weak radio waves. During the search for pulsars in the Milky Way, Han Jinlin's team recorded the spectral line data of interstellar medium synchronously, revealing the delicate structure of neutral hydrogen gas in the Milky Way and the diffuse characteristics of ionized gas. They also detected small clouds that are 60000 light years away from the center of the Milky Way and can't be seen by other telescopes, providing high-quality observation data sets for frontier topics such as gas dynamics research and spiral arm structure of the Milky Way. In addition, the team also measured the Faraday effect of a large number of faint pulsars, showing the characteristics of a wide range of magnetic fields in the deep region of the Milky Way, and newly identified the remains of two supernova explosions. Jing Yipeng, the chief editor of the special topic and academician of Shanghai Jiaotong University, said, "The highly sensitive FAST observation revealed unprecedented details of the Milky Way. The neutral hydrogen and ionized hydrogen databases published by the research team can be used to explore many characteristics of the intergalactic gas in the Milky Way, providing valuable data resources for astronomers around the world." It was reported that Han Jinlin's team was still making efforts to survey the Milky Way region visible to FAST, The goal is to complete the survey of the 2900 square degree region of the Milky Way. (Liu Xinshe)