There are 150-400 billion stars in the Milky way. The Milky way is the rod spinning star system where the solar system is located. The galaxy includes a large number of stars, star clusters, nebulae, as well as various types of interstellar gas, interstellar dust and black holes. Its total visible mass is 210 billion times the mass of the sun, and its diameter is between 100000 light-years and 180000 light-years.
The main part of the Galactic material consists of a thin disk called the silver disk. The spherical part of the bulge in the center of the silver disk is called the nuclear sphere, where stars are highly dense. There is a small dense area in the center of the nuclear ball called the silver core. Outside the silver disk is a larger, nearly spherical area, in which the material density is much lower than that of the silver disk, which is called silver halo. There is also a silver crown outside the silver halo, and its material distribution is roughly spherical.
Columbia University scientists have accurately calculated the mass of the Milky way. The latest results believe that the mass of the Milky way is about 210 billion times that of the sun, including star clusters with thousands of stars on the edge of the Milky way. Scientists have obtained the mass distribution map of the Milky way after running the supercomputer, and the calculated mass of the Milky way is the most accurate. This research result is helpful for us to study the structure of the Milky way, such as the span of the Milky way. Our previous estimate of the mass of the Milky way comes from observing the speed at which stars move, which has a huge error.