The sun belongs to a very common category of star—the "main sequence''—and there exist billions and billions of very similar stars. Stars are grouped into galaxies, systems usually extremely "squashed," in the shape of a disk, made up of billions of stars rotating around a central nucleus. The sun is no exception to the rule, and is situated at a certain point of one of these disks. We who dwell on an insignificant planet orbiting around an insignificant star belonging to an insignificant galaxy—call it the Milky Way. Because we are inside it, and because it is shaped like a disk, we see it as narrow band of diffused luminosity traversing the sky. Since its luminosity is diffuse, the Milky Way is not clearly visible when pollution or artificial light is present, whereas its presence becomes quite striking and spectacular if the night sky is clear and we are viewing it from a very dark area.
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