The interstellar medium is mainly filled with gaseous hydrogen. A considerable amount of helium and a small amount of substances were also detected, followed by calcium, water, ammonia and formaldehyde. In addition, there are a considerable number of dust particles with uncertain composition. Finally, there are primary rays that pass through interstellar space and magnetic fields that span many places in the region. In most cases, interstellar medium appears in the form of cloud-like aggregates, and sometimes its concentration is enough to form stars. On the other hand, stars keep losing mass, some in the form of small explosions, while others explode into supernovae. In this way, the mass is fed back to the interstellar medium and mixed with the matter that has not yet formed a star. The circulation of interstellar matter through stars largely determines the content of heavy elements in the cosmic clouds. The interstellar matter in the Milky Way mainly exists outside it, the so-called spiral arm, where there are a large number of young stars and nebulae. Interstellar matter is closely gathered in galactic plane, and galactic plane is a flat area, commonly known as the Silver Plate. Radio telescopes can study and explain radio waves emitted by various components of interstellar medium. For example, neutral hydrogen absorbs or emits a very small amount of radio energy with a unique wavelength of 2 1 cm. By measuring this wavelength and comparing it with adjacent wavelengths, hydrogen absorption clouds or hydrogen release clouds can be detected.