As one looks at the night sky, they observe a hazy band of white light that they always infer to be the Milky Way. Apparently, this is not true because every star and celestial body seen by the naked eye in the night sky all belong in the Milky Way. However, the band of white light comes about as a result of the accumulation of unresolved stars and other materials. A dark region can also be observed within the white band. The shaded area corresponds to blocked light from the distant star by interstellar dust.
The Milky Way mainly consists of a bulging center and a spiral disk. The spiral disk can further be classified into a thin and thick disk. The flat disk rises about a 1000 light years below and above the galactic mid-plane, and the thick disk extends to about 3500 light years on both sides of the plane. When one considers the flatness of the galaxy then the galactic disk is said to be 120,000 light-years across. Our sun is about 28,000 light-years from the galactic center within the thin disk. There is also a halo that surrounds the entire disk, but it is not visible because of its dark matter composition.
The Milky Way consists of many stars. These stars vary in lots of ways, from their individual size to their composition. The stars also vary depending on where they are found within the galactic disk, for example, those in the halo differ from those found on the disk. Consequently, they are said to belong to different stellar population. The mass of a star also translates to its life span. their weight is usually measured in terms of solar mass. The lighter the solar mass the longer the stars life span.
The Milky Way is just one galaxy in a collection of a group of galaxies called the Local group. The Milky Way moves at 300 km/sec in the direction of the constellation Virgo. The Milky Way is in constant movement with the other galaxies in the Local Group.